AGCO Allis 6690 Tractor 86 hp Overview, Specifications, and Performance
AGCO Allis 6690 Tractor 86 Hp
The AGCO Allis 6690 is a tractor built for mid-sized farm work. You get about 86 horsepower from its 4.4-liter, 4-cylinder diesel engine made by Deutz.
This allows you to use the tractor for many types of field and haul work. You’ll find a comfortable cab, 2WD or optional 4WD, and a 3-point hitch for attaching common implements.
The 6690 also comes with two rear hydraulic remotes, which makes it easy to use tools that need hydraulic power. The rear 540 PTO lets you run mowers, balers, or other PTO-driven equipment.
PTO horsepower is rated at about 81 hp, with drawbar horsepower near 69 hp. Hours of use can vary, but many used models have reliable records.
The tractor is part of AGCO Allis’s 40–99 hp range. It fits in well if you need power that falls between small and large tractors.
Here’s a table to help organize the main details of the AGCO Allis 6690:
| Feature | Description |
|---|---|
| Engine | 4.4L, 4-cylinder Deutz diesel |
| Gross Horsepower | 86–90 hp |
| PTO Horsepower | About 81 hp |
| Drawbar Horsepower | About 69 hp |
| Drive Options | 2WD, Optional 4WD |
| PTO | Rear 540 |
| Hydraulics | Two rear remotes |
| Hitch | 3-point (Category 2) |
| Common Uses | Tillage, hay, hauling, loader work |
You can use the AGCO Allis 6690 for row crops, haying, and basic farm chores. It has a reputation for strong performance in medium-duty tractor tasks.
Production & Identification
The AGCO Allis 6690 tractor was built for reliability and steady performance on farms. Understanding its manufacturer, model identifiers, and origin details will help you recognize and evaluate this tractor more confidently.
| Subtopic | Details |
|---|---|
| Manufacturer / Brand | AGCO (Allis), Allis Chalmers influence |
| Model Number / Series | 6690, 6600 Series |
| Factory of Manufacture | Italy |
| Years Produced | 1991–1997 |
| Original List Price | Estimated, not widely published |
| Serial-Number Location | Stamped plate, frame or dashboard area |
Manufacturer / Brand
You will find that the AGCO Allis 6690 was produced by AGCO Corporation, a well-respected name in agricultural equipment. The brand AGCO Allis represents the merger of AGCO’s ownership with historical assets from Allis-Chalmers, which was a significant player in tractor design and production for decades.
AGCO acquired the North American assets of Allis-Chalmers in the early 1990s. From then, newer tractor lines like the 6690 began to carry the AGCO Allis name, blending modern engineering with familiar Allis Chalmers heritage.
This branding reflected both continuity for loyal customers and AGCO’s commitment to newer innovations in tractors.
Model Number / Series
The AGCO Allis 6690 belongs to the 6600 Series. This model number is clearly printed on the tractor’s body panels, typically on the hood or side decals.
The “6690” identifies its approximate engine horsepower as well, making it easy for you to distinguish from similar units such as the 6670 or 6680. Series numbers in the AGCO Allis lineup follow a pattern where the first digits refer to the series, and the last digits often indicate the horsepower.
Factory of Manufacture
The AGCO Allis 6690 was manufactured in Italy. The Italian factories used for this production were part of the Same-Lamborghini-Hurlimann (SLH) group, which AGCO partnered with during the 1990s for certain models.
This means that while you get the branding of AGCO and Allis, the 6690 has core engineering and components based on European tractor designs. Italian-built AGCO Allis tractors are often recognized for their robust 4-cylinder diesel engines and reliable European parts.
Years Produced
The AGCO Allis 6690 stayed in production from 1991 until 1997. During these years, it was offered mainly in North America, but also saw limited distribution in other international markets.
If you are looking to date your tractor or estimate its age, you can use this production window as a starting point. Tractors made before 1991 would fall under previous Allis-Chalmers lines, and tractors after 1997 would belong to AGCO series with different numbers or branding.
Original List Price (Launch Year)
A precise original list price of the AGCO Allis 6690 at launch is difficult to find, as dealership pricing varied by country, dealer, and factory options. Estimated values suggest the launch price in the United States was in the range of $34,000 to $38,000 USD (mid-1990s dollars).
This price level placed the 6690 in the mid-size utility tractor segment, affordable for medium-sized farms or operations seeking a reliable workhorse.
Serial-Number Location
You can find the serial number of the AGCO Allis 6690 on a stamped metal plate mounted on the tractor frame, near the front left side below the engine hood. Sometimes, the plate is also located inside the cabin area or on the right-hand side of the dashboard, depending on factory batch.
Checking the serial number is important if you wish to verify the specific model year, ensure correct replacement parts, or trace prior ownership. Keeping your serial number accessible also aids in registration and insurance.
Engine Specifications
The AGCO Allis 6690 tractor is built around a reliable diesel engine designed for mid-range farming tasks. You get dependable performance, practical power, and simple maintenance features essential for regular field work.
Engine Make & Model
The AGCO Allis 6690 uses a SLH (SAME/Lamborghini/Hürlimann) 4.0-liter diesel engine, often referenced as the Deutz F4L in several manufacturing records. This inline 4-cylinder engine has earned a reputation for solid reliability and is used in many mid-sized tractors.
The engine’s design focuses on durability and efficiency. Known for easy servicing and strong parts support, the engine’s reputation makes it a favorite among owners.
It does not use any complex turbocharging or electronic management systems, making it easy to repair using standard tools.
Fuel Type & Emissions Tier
You will run the AGCO Allis 6690 on diesel fuel, which is standard for agricultural tractors in this class. The engine is naturally aspirated and not modified for alternative fuels like biodiesel or propane.
Emissions standards for this tractor reflect its late-1980s to mid-1990s production period. The engine does not meet the latest U.S. EPA Tier restrictions that apply to new tractors.
There are no DEF systems, particulate filters, or EGR setups present. Simplicity here is a plus for maintenance, but it may limit shipping to regions with strict no-emissions-import laws.
Cylinders / Displacement
This tractor uses a 4-cylinder engine laid out in an inline configuration. The displacement is 244 cubic inches (4.0 liters).
Displacement refers to the total volume pushed by all pistons as the engine completes its cycle. A 4-cylinder layout is efficient and helps balance performance with fuel efficiency.
The engine block is robust, helping resist wear over long working hours. The 4.13-inch bore and 4.55-inch stroke provide a good torque curve for field operations.
| Feature | Specification |
|---|---|
| Number of Cylinders | 4 (Inline) |
| Displacement | 244 cu in (4.0 liters) |
| Bore | 4.13 in (105 mm) |
| Stroke | 4.55 in (116 mm) |
Rated Horsepower (Gross & Net)
AGCO rates the 6690 engine at 86.91 horsepower (about 64.8 kW) at the engine flywheel. This is commonly referred to as the gross horsepower rating.
The net horsepower, which accounts for basic engine parasitic losses before PTO and hydraulics, is only slightly lower, so you still get efficient usable power at the drawbar. At the PTO (Power Take-Off), the tested output averages around 80.85 PTO horsepower.
The engine sustains this power output at rated speeds, making it dependable for mowing, baling, and mid-duty tillage.
| Output Type | Power Output |
|---|---|
| Gross Horsepower (Rated) | 86.91 hp (64.8 kW) |
| PTO Horsepower (Tested) | 80.85 hp (60.3 kW) |
| Drawbar Horsepower | 68.53 hp (51.1 kW) |
Peak Torque (Nm @ Rpm)
Peak torque numbers allow you to understand how the tractor pulls when the work gets heavy. The manufacturer does not regularly publish the exact peak torque figure for this engine.
However, you can expect torque in the range of 300 to 320 Nm (221 to 236 lb-ft) at approximately 1,600–1,800 rpm. Torque at low rpm delivers lugging capability, so the tractor keeps moving in tough soil, when baling, or under heavier PTO loads.
The combination of bore and stroke supports a flat torque curve, which helps with consistent pulling power. Since there are no turbochargers, the torque buildup is linear, letting you manage power delivery smoothly with the throttle.
You do not need high revolutions to get most of the usable force from this engine.
Compression Ratio
This diesel engine operates at a compression ratio of around 17:1. Diesel engines run at higher compression than gasoline engines, helping ignite fuel without spark plugs.
The higher compression ratio improves fuel efficiency and cold start ability. You will notice a quicker start in cold weather, and the engine is less likely to require ether or extensive pre-heating except in severe conditions.
The robust construction needed to withstand this compression also contributes to the engine’s long life cycle. The high compression helps create the torque necessary for field tasks without overstressing engine parts.
Cooling System & Capacity
The AGCO Allis 6690 is equipped with an air-cooled system, rather than a conventional water cooling system. This feature is uncommon but effective for easy maintenance and fewer freezing concerns.
You will not need to check or replace coolant, deal with radiator flushes, or worry about leaks in hoses or water pumps. The cooling fins need occasional cleaning to prevent dust buildup, but there are fewer parts to fail compared to liquid cooling systems.
The engine oil system typically requires 9.2 quarts (8.7 liters) of oil, which doubles as both lubrication and a partial heat transfer medium in this air-cooled design.
| System | Type / Capacity |
|---|---|
| Cooling | Air-cooled |
| Engine Oil Capacity | 9.2 quarts (8.7 liters) |
Engine Specifications Table
| Section | Details |
|---|---|
| Engine Make & Model | SLH (SAME/Lamborghini/Hürlimann) / Deutz F4L, 4-cyl diesel |
| Fuel Type & Emissions | Diesel only, non-emission controlled |
| Cylinders / Displacement | 4 cylinders / 244 cu in (4.0 L) |
| Horsepower (Gross/PTO) | 86.91 hp gross / 80.85 hp PTO |
| Peak Torque | ~300–320 Nm @ 1,600–1,800 rpm (estimate) |
| Compression Ratio | ~17:1 |
| Cooling System | Air-cooled, no liquid coolant needed |
| Oil Capacity | 9.2 quarts (8.7 liters) |
Power Take-Off (PTO)
The AGCO Allis 6690’s PTO is designed for versatility and supports heavy farm tasks, from rotary mowers to balers. You have control over horsepower output and the PTO connection type, making sure your implements run smoothly and efficiently.
Claimed PTO Horsepower
The AGCO Allis 6690 delivers reliable PTO horsepower for medium and heavy-duty farm equipment. It is rated at 86 engine horsepower, but the PTO horsepower is slightly lower to account for power lost in the drive system.
You get about 72 to 75 PTO horsepower available at the shaft. This rating is enough for most implements like large mowers, balers, augers, and manure spreaders.
You should always match your implement’s requirements to this rating. Knowing the PTO horsepower helps prevent your tractor from being overloaded, which keeps both your tractor and your equipment from suffering damage.
PTO Type (Independent / Live / Economy)
The tractor comes with an independent PTO. This means you can engage or disengage the PTO shaft at any time, no matter what the tractor’s transmission is doing.
Independent PTO makes it easier to control powered implements without stopping or starting the tractor itself. You will use a hydraulic wet disc clutch to operate the PTO.
This system is more durable and runs cooler than older mechanical dry clutches. You will notice less wear and smoother engagement, especially when running heavy or high-inertia attachments.
There is no economy PTO included, which means there’s no special lower-speed setting for reduced fuel use.
PTO Speeds (540 / 1 000 Rpm)
You can select between two standard PTO speeds: 540 RPM and 1,000 RPM. This dual-speed design gives you flexibility when running different types of attachments that need different shaft speeds.
For smaller implements like post-hole diggers or smaller mowers, you will likely use the 540 RPM setting. Larger implements, such as big mowers and some balers, often need the 1,000 RPM option for the best performance.
Switching between speeds is done by selecting the correct PTO output shaft. The rear PTO shaft has 21 splines for 1,000 RPM use.
This dual-speed feature extends what farm attachments you can pick for your tractor.
| Feature | Specification / Description |
|---|---|
| Claimed PTO Horsepower | 72–75 HP at the shaft |
| PTO Type | Independent, hydraulic wet disc clutch (no economy PTO) |
| PTO Engagement | Operate at any time, regardless of tractor movement |
| PTO Speeds | 540 RPM (6-spline) and 1,000 RPM (21-spline) rear shafts |
| PTO Suitability | Works with a wide range of implements, medium and heavy-duty use |
| Control | Lever or button-operated, separate from main transmission |
Transmission & Drivetrain
This tractor gives you strong choices for handling fieldwork and transport. There are multiple transmission options, drive configurations, and smart features for traction and control.
Transmission Type (Syncro, Powershift, CVT, HST)
The AGCO Allis 6690 offers several transmission types, with the most common being a partial power shift. The partial power shift supports quick changes between speed ranges, which helps you adjust to varying conditions without fully stopping or using only the clutch.
Some models also feature synchromesh transmissions, letting you shift easily between gears for smoother operation in the field or on the road. You won’t find a CVT (continuously variable transmission) or HST (hydrostatic transmission) on this tractor.
A traditional clutch system is used, giving direct mechanical connection and simple maintenance. The clutch is usually a heavy-duty, dual-stage type that manages both the transmission and the PTO.
This setup is built for both durability and straightforward operation.
Number of Gears / Ranges
The AGCO Allis 6690 is available with several transmission configurations depending on the specific model and market. The most advanced has 30 forward and 30 reverse speeds created by combining five main gears in three ranges (low, medium, high) and a high-low power shift for each gear.
This gives you a lot of flexibility for matching any fieldwork speed or transport need. Other models may come with 16, 12, or 24-speed options, usually based on a combination of gear selections and range levers.
Synchromesh versions often have 12 forward and three reverse gears. Each setup gives you enough choices to handle both light and heavy loads, and makes shifting less complicated.
More gears mean finer speed control, which is important for tillage, planting, or transport.
Top Transport Speed
Top speed for the AGCO Allis 6690 is usually around 25-30 km/h (15-19 mph), depending on transmission type and tire size. With the partial power shift or 30-speed setup, you can reach top speed in a high gear and high range.
This makes road transport between fields faster and more efficient. Transport speed also depends on how you set the ranges.
Having many gears helps you find a good balance between engine RPM and ground speed. The main benefit is you can transport implements and move quickly without over-revving the engine or slowing down traffic.
Drive (2WD / 4WD / AWD)
You can choose between 2WD (two-wheel drive) and 4WD (four-wheel drive) for the 6690. The 2WD model is standard and fits many field uses with dry, level ground.
The 4WD (also called MFWD or mechanical front-wheel drive) option gives extra pulling power, which helps with heavy tillage, soft soils, or muddy fields. The front axle design on 4WD models provides better traction and stability, especially with front loaders or heavy implements.
Switching between 2WD and 4WD is generally done with a lever in the cab, so you can quickly adapt to field conditions. There is no all-wheel drive (AWD) system; only front and rear axles are powered in 4WD mode.
Differential-Lock & Final Drives
The AGCO Allis 6690 is equipped with a differential-lock, which can be controlled by a foot pedal or lever in the operator’s station. Using the differential-lock helps keep both rear wheels turning together when a wheel slips, giving much better traction in slick or uneven conditions.
The final drives are robust and designed to deliver torque smoothly to the ground. Gear-driven final drives at the rear axles are common, which increases durability under high loads and limits maintenance needs.
The differential-lock and strong final drives work together to keep you moving in tough ground conditions.
| Feature | Details |
|---|---|
| Transmission Type | Partial power shift (main), also available as synchromesh (varies by model) |
| Gears / Ranges | 30×30 (forward/reverse), other options: 16, 12, 24-speed (depending on specification) |
| Clutch Type | Dual-stage, manual clutch |
| Top Transport Speed | 25-30 km/h (15-19 mph), variable by transmission/tire |
| Drive Configuration | 2WD standard, 4WD (MFWD) optional |
| Differential-Lock | Foot pedal or hand lever actuated |
| Final Drives | Heavy-duty, gear driven |
Steering & Brakes
The AGCO Allis 6690 tractor features a power-assisted hydrostatic steering system, reliable wet disc service brakes, and a standard mechanical parking brake. These components work together to give you steady control and safety while operating the tractor for various tasks.
| Feature | Details |
|---|---|
| Steering System | Hydrostatic, power-assisted |
| Turning Radius | Tight; reduced further with brake use |
| Service Brakes | Wet disc |
| Parking Brake Type | Mechanical hand-lever |
Steering System (Hydrostatic / Power-Assisted / Mechanical)
You get a hydrostatic, power-assisted steering system on the AGCO Allis 6690. This means turning the wheel is smooth and requires little effort, even when handling heavy implements or at low speeds.
The hydrostatic system uses hydraulic pressure, so steering remains responsive and consistent. When working long hours or making frequent turns, this system helps reduce fatigue.
If you compare it to older mechanical systems, you will find the 6690’s steering offers better maneuverability and less strain on your arms and shoulders. You can trust it to perform well in fields or confined spaces around the farm.
A properly maintained steering pump and fluid level are essential for smooth operation. Low hydraulic oil can make the wheel harder to turn or cause noise, so it’s important to check this often.
Most maintenance centers stock replacement parts if you need service.
Turning Radius (With Brakes)
Tight turns are often needed when planting, cultivating, or working around buildings. The 6690’s steering, combined with effective braking, lets you make sharper turns than with steering alone.
When you engage one of the individual wheel brakes, you can pivot the tractor more closely around the inside wheel. This feature helps when navigating narrow fields or turning at the end of a row.
It reduces the time and space needed to line up your next pass. Proper brake adjustment keeps this function working correctly; worn or misadjusted brakes can lead to wider, less precise turns.
For operators working in tight spots, combining steering and individual braking is especially useful. Controlled turning also lowers the risk of clipping posts or edging out of bounds in small areas.
Service Brakes (Wet Disc, Dry Drum, Etc.)
The AGCO Allis 6690 uses wet disc service brakes. These brakes are located in an oil bath inside the axle housing, so they stay cool during heavy use.
Wet disc brakes offer strong, even stopping force in all conditions, including rain, mud, or dusty environments. Unlike dry drum brakes, wet disc types are less likely to overheat or lose effectiveness during repeated stops.
They need less frequent service than drum brakes, though regular checks are advised for hydraulic oil and disc wear. Wet disc brakes are also quieter during operation and give a more gradual stop.
If you need to replace them, most parts dealers can supply discs and seals specific to the 6690.
Parking Brake Type
You have a mechanical hand-lever parking brake on this model. It is easy to operate and locks the wheels in place when the tractor is parked or idle, providing an important safety feature.
The hand lever is usually positioned near the operator for quick access. To engage the parking brake, simply pull the lever until it clicks firmly in place.
This system is straightforward with few parts to maintain. It’s still important to check the cable tension and lever action during routine inspections.
A worn or loose cable can make the parking brake less effective. Regular adjustment ensures that the tractor stays securely parked, especially on slopes or uneven ground.
If you need replacement parts, standard kits are available for the AGCO Allis 6690.
Cab & Operator Station
The AGCO Allis 6690 is equipped with features designed to give you a comfortable and safe working experience. You get a well-designed operator area with protection, climate control options, and good visibility while using this tractor.
ROPS / Cab Option
You can get the AGCO Allis 6690 with either an enclosed cab or an open station with a roll-over protective structure (ROPS). The cab version is a popular choice because it shields you from weather and reduces exposure to dust and noise.
The doors and windows give full visibility in all directions, which helps when attaching implements or working in tight spots. On ROPS models, you have open access and a simple design.
This setup is lighter, gives more headroom, and works well if you prefer open-air operation. ROPS meets current safety regulations and aims to protect you if the tractor tips over.
The cab doors close securely and have sturdy handles. Windows can be opened for ventilation if you do not want to use climate controls.
When you are deciding, choose the cab if you want more comfort, or go with ROPS if you like simplicity and lower cost.
Climate Control (A/C, Heater, Filter)
The AGCO Allis 6690 cab comes with a full climate control system. Air conditioning (A/C) allows you to stay cool even on hot days.
You can adjust temperature and airflow with simple controls mounted above or beside the operator seat. The heater keeps the cab warm during cold months, so you can work year-round.
A fresh air intake system draws air from outside and passes it through a good quality filter. This helps keep dust and pollen out of the cab, making it easier to breathe and protecting electronics.
You can direct both cool and warm air with vents aimed at your face, feet, or windows. Air circulation keeps the windshield clear and stops fogging on damp mornings.
The combination of A/C and a strong heater means you have control over the inside environment. The fan speed control lets you set the airflow anywhere from a low breeze to a powerful blast, so you can adjust it to your needs.
Seat & Suspension
You sit on a wide padded seat that supports long hours of fieldwork. It comes standard with adjustable fore-aft position and backrest angle.
This lets you set the seat where you want for maximum comfort. The seat suspension system is designed to absorb rough shocks when you drive over uneven ground.
The suspension can usually be fine-tuned for your weight, which helps prevent soreness during long days. Armrests on both sides are common and add to your stability.
The high backrest gives support for your shoulders and neck, reducing tiredness. You have a seat belt for safety.
The seat fabric or vinyl cover is made for easy cleaning if it gets muddy or dusty. If you choose the suspension seat upgrade, it does a better job of smoothing out small bumps and makes noticeable difference when working in rough fields.
Noise Level (dB A @ Operator Ear)
AGCO Allis 6690 tractors with a cab have better sound insulation compared to open ROPS models. The cab’s solid doors and seals block engine noise, so you can work in a quieter environment.
Typical sound levels inside the cab are in the range of 75-80 decibels A-weighted (dB A), close to normal conversation levels. On ROPS models, sound levels can reach above 85 dB A, especially during heavy engine load.
Noise mostly comes from the engine and the rear PTO. Prolonged exposure to noise above 85 dB A is not recommended without hearing protection.
The cab lining is made from sound-deadening materials, which cut vibration and lower noise at the operator’s ear. Windows and panels are fitted tightly to minimize rattles.
This makes it easier to talk with someone, listen to a radio, or focus on your work without getting tired from loud sounds.
| Feature | Cab Option | ROPS Option |
|---|---|---|
| Protection | Enclosed, weatherproof, locks | Open, roll-over protection |
| Visibility | 360°, with glass doors and windows | Open sides, good sight |
| Climate Control | Air conditioning, heater, filtered ventilation | None |
| Seat & Suspension | Adjustable, suspension system, armrests, high back, seat belt | Adjustable, basic seat |
| Noise Level (dB A) | 75-80 (inside cab) | 85+ at operator ear |
| Air Filtration | Yes, fresh air with dust filter | None |
| Comfort Level | High, all-weather, reduced vibrations and sound | Basic, exposed environment |
Hydraulics
The AGCO Allis 6690 features a hydraulic system designed for reliability and sufficient power. This part of the tractor handles implements, steering, and remote functions using modern open-center technology.
System Type (Open-Center / Closed-Center / PFC)
The hydraulic system on the AGCO Allis 6690 is an open-center type. In this system, hydraulic oil flows continuously through the pump and back to the reservoir when none of the control valves are activated.
You do not get pressure on demand as with a closed-center or PFC (Pressure and Flow Compensated) system, but you do benefit from mechanical simplicity and consistent flow. This open-center design is common on utility and mid-sized row crop tractors.
It’s less complex than closed-center systems, which can mean easier repairs and lower maintenance costs. For most typical tasks—like lifting implements, operating loaders, or running simple attachments—this setup works well.
Open-center hydraulics are known for steady, predictable performance. However, keep in mind they do not adjust flow to demand, so efficiency at low loads is less than what you might find with a closed-center setup.
Implement Pump Flow (L min⁻¹)
The hydraulic pump for implements on the AGCO Allis 6690 provides a flow rate of about 57.5 liters per minute (L/min). This translates to solid performance for running most implements designed for a tractor in this power rating.
A pump flow in this range is suitable for front-end loaders, hydraulic mowers, hay tools, and other typical equipment. You can expect quick response times and good lifting speeds when operating implements.
This pump flow rate is a central factor in determining how quickly attached machinery responds to control inputs. If you are planning to run implements that require high hydraulic flow, check your equipment’s requirements.
Most standard implements in this horsepower class will be fully supported by the AGCO Allis 6690’s pump flow.
Steering Pump Flow (If Separate)
On the AGCO Allis 6690, steering shares the hydraulic system with the implements, so there is no separate steering pump. The open-center system provides hydraulic power for both steering and auxiliary functions from a single pump.
This shared arrangement keeps the system simple and lowers maintenance needs. However, heavy implement use or using multiple hydraulic tools at once can sometimes reduce steering response.
On most jobs, steering remains firm and responsive, as the pump is sized to supply enough flow for both tasks under practical working conditions. You do not need to worry about managing two hydraulic reservoirs or separate lines for steering.
All functions are supported by a single integrated system.
Total Combined Flow
The total combined flow from the hydraulic pump is about 57.5 L/min (15.2 gallons per minute). Both implement and steering circuits draw from this total capacity, which means you have a strong supply of oil flow for various applications.
This combined flow rate provides good hydraulic power for multitasking on the farm. Lifting heavy loads with a loader, using hydraulic cylinders, or steering at low speeds are supported effectively.
Keep in mind that simultaneous operation of multiple functions may reduce available flow for each function, but in general usage, this system meets most farm needs.
The table below summarizes key hydraulic specifications for the AGCO Allis 6690:
| Feature | Specification |
|---|---|
| System Type | Open-center |
| Implement Pump Flow | 57.5 L/min (15.2 gal/min) |
| Steering Pump Flow | Not separate (shared pump) |
| Total Combined Flow | 57.5 L/min (15.2 gal/min) |
| System Pressure | See next section |
| Remote Valves | 2 (see below) |
System Pressure (bar / psi)
The AGCO Allis 6690 hydraulic system works under a maximum pressure of around 190-200 bar (2,755-2,900 psi). This system pressure gives you the force needed to lift, tilt, and operate most agricultural implements.
The pressure is managed so equipment works safely and efficiently without the risk of system overload. At this pressure, the tractor is able to support demanding tasks like loader work, hay handling, or running hydraulic cylinders for attachments.
Consistent high system pressure is also important for keeping steering responsive and operating functions smoothly. Always make sure hydraulic hoses and connectors are rated for this pressure to prevent leaks or failures.
Remote Valves (Number & Type)
You get 2 standard hydraulic remote valves on the AGCO Allis 6690. These are located at the rear of the tractor and are used to power external implements such as mowers, rakes, log splitters, or other hydraulic tools.
The remotes are single-acting or double-acting based on your need, and each can be controlled independently from the operator’s seat. The valves are lever-controlled and are designed for durability.
If you need more remotes, aftermarket kits may be available, but most users find the standard setup covers their equipment needs. These hydraulic remotes make it easy to plug in and operate a range of tools, supporting flexibility in field operations.
Hydraulics Feature Table
| Subtopic | Detail |
|---|---|
| System Type | Open-center |
| Implement Pump Flow | 57.5 L/min (15.2 gal/min) |
| Steering Pump | Not separate; shared with implements |
| Total Combined Flow | 57.5 L/min (15.2 gal/min); shared across functions |
| System Pressure | 190-200 bar (2,755-2,900 psi) |
| Remotes | 2 standard, rear-mounted (single/double-acting) |
Three-Point Hitch (3PH)
The AGCO Allis 6690 uses a three-point hitch system designed for flexibility and strength. Its setup is suitable for a wide range of implements and field conditions.
Hitch Category (1 / 1N / 2 / 3)
Your AGCO Allis 6690 is fitted with a Category II three-point hitch. This category is common for tractors in the 40–100 horsepower range.
Category II hitches have stronger arms and larger pins than Category I, allowing them to handle heavier implements and more demanding jobs. The pin diameter for Category II is 1 inch (lower) and 7/8 inch (top link).
Spacing between the lower link arms is about 32 inches. This makes connecting larger plows, discs, and mowers straightforward and secure.
Most modern implements within the 6690’s horsepower range are compatible. When checking for compatibility, match the implement’s category rating and pin size to your hitch for the safest and best performance.
Lift Capacity @ Ball Ends
The lift capacity at the ball ends is a key figure—it tells you how much weight you can safely lift with your hitch. On the AGCO Allis 6690, you can expect a lift capacity at the ball ends of around 4,400 to 5,000 pounds, depending on specific configuration and hydraulic condition.
This capacity means you can handle large implements like heavy disc harrows, seeders, and mounted plows. Always check the implement’s weight and remember your lift arms handle the most weight right at the ball ends.
If you mount tools farther back, leverage reduces what you can lift. Hydraulic pressure and system health impact actual lifting ability.
Make sure to keep your hydraulic fluid clean and topped up for the best performance.
Draft / Position Control
You have both draft and position control on the AGCO Allis 6690. Position control lets you raise or lower implements to precise heights.
Draft control automatically adjusts the depth of soil-working implements by sensing resistance at the lower links. This system helps keep plows or cultivators working at a steady depth in changing field conditions.
On rough or hilly ground, draft sensing can reduce strain on both your equipment and tractor. You select between draft and position modes using the lever in your cab.
Many operators use position control for mowers and draft control for plowing or tillage. Adjusting each to your field’s needs improves productivity and reduces wear.
Top-Link Sensing (Yes/No)
The AGCO Allis 6690 does not include top-link sensing in its standard configuration. This means draft control is operated by sensing forces through the lower links, not the upper (top-link).
Without top-link sensing, the system may react a bit slower under extreme changes in implement load. Most field operations, though, work very well using the lower-link sensing system.
For most operators and tasks, the difference is minor. If you use highly specialized or automatic depth-sensitive tools, top-link sensing might be missed, but for general work, you will find the standard setup adequate.
| Feature | Details |
|---|---|
| Hitch Category | Category II (1″ lower pin, 7/8″ top pin, ~32″ spacing) |
| Lift Capacity @ Ball Ends | 4,400–5,000 lbs (varies by exact spec and hydraulic condition) |
| Draft / Position Control | Both included; lever selection; draft through lower-link sensing |
| Top-Link Sensing | No |
| Compatible Implements | Suited for Category II; large plows, discs, mowers, tillage tools |
| Best Maintenance Practices | Check hitch pin size, hydraulic fluid level, and arm condition |
Axles & Load Limits
The AGCO Allis 6690 has specific axle ratings designed to handle both heavy implements and long hours in the field. Knowing these limits is important to avoid damaging the tractor or reducing its lifetime.
Maximum Front-Axle Load (kg)
The front axle carries much of the weight during loader work or when heavy implements are mounted up front. For the AGCO Allis 6690, the maximum front-axle load depends on whether your tractor is a 2WD or 4WD model.
The 4WD model generally supports more weight at the front because of the upgraded axle design and larger components. Using the information available, a typical safe working limit for the front axle on similar tractors is about 2,500 kg (5,512 lbs) for 4WD versions.
The 2WD models are rated for a bit less due to smaller axle size. You should check your operator’s manual for the exact number for your serial range.
Always factor in added weight from front ballast or a front loader. Avoid overloading as too much weight can stress steering parts or cause early axle wear.
Maximum Rear-Axle Load (kg)
The maximum rear-axle load is higher than the front since most drawbar and three-point hitch work transfers weight to the rear. The AGCO Allis 6690 2WD configuration has a rear axle capacity of about 11,464 lbs (5,200 kg), while 4WD models are similar or slightly higher.
Rear-axle limits include the combined weight of the tractor, mounted implements, any ballast, and load in the tires. Staying under this limit helps prevent axle failure and maintains safe handling.
If you use heavy rear attachments, monitor the load closely. Overloading can impact tire life and affect braking, especially when towing trailers or large implements.
Final-Drive Type
The final-drive system on the AGCO Allis 6690 is a heavy-duty unit designed for high torque transfer. This model uses a flange axle final-drive setup, providing a solid mount for wheels and consistent power delivery.
Flange axles are common on utility tractors and are valued for their strength and reliability. This type supports fast coupling of dual wheels and stands up well to stress from heavy fieldwork.
In the 4WD version, the final drive is reinforced for extra strength. This makes it well suited for tough jobs.
Lubrication and regular inspection are important to prevent wear and catch leaks early. Check axle seals often to avoid downtime.
| Feature | 2WD Model | 4WD Model | Notes |
|---|---|---|---|
| Max Front-Axle Load | ~2,000–2,300 kg (estimate) | ~2,500 kg (approximate) | Check actual in your service manual |
| Max Rear-Axle Load | 5,200 kg (11,464 lbs) | Similar or a bit higher | Limit includes ballast and implements |
| Final-Drive Type | Flange axle | Heavy-duty flange axle | Allows dual wheels and high-torque use |
| Front Axle Build | Standard | Reinforced | 4WD for more demanding jobs |
| Rear Axle Diameter | Large | Large | Suitable for heavy field attachments |
Tires & Track Options
The AGCO Allis 6690 tractor offers different tire and track setups to suit a wide range of farming needs. Tire sizes depend on if you use two-wheel drive (2WD) or four-wheel drive (4WD), and you may have choices for extra stability or traction.
| Option | Front Tires | Rear Tires | Drive Type | Extra Options |
|---|---|---|---|---|
| Standard Ag Tires (2WD) | 7.50-18 | 16.9R34 | 2WD | Optional Duals |
| Standard Ag Tires (4WD) | 14.9R24 | 16.9R34 | 4WD | Optional Duals |
| Alternative Tire Sizes (Auction) | 9.5R36 | 11.2R46 | Not specified | Not specified |
| Track & Flotation Kits* | Not factory standard | Not factory standard | N/A | Aftermarket kits possible |
*Tracks/flotation kits mentioned for reference; factory options not standard.
Standard Front Tire Size (Ag / Turf / Industrial)
For the AGCO Allis 6690, the front tire size depends on your drive system. With 2WD, the standard agricultural tire is 7.50-18.
For 4WD models, it changes to 14.9R24. This larger size on 4WD helps improve traction and steering, especially in difficult field conditions.
Turf and industrial front tires were not typically standard from the factory. If your main work is on lawns or construction sites, you may look for compatible turf or industrial tire sizes through aftermarket suppliers.
Most models found at auction are set up with agricultural tires. Correct front tire size is important for both stability and to avoid excess wear on your tractor’s steering system.
Be sure to check that replacement tires match the size and load rating required for your drive type.
Standard Rear Tire Size
On both 2WD and 4WD models, the standard rear tire for the AGCO Allis 6690 is 16.9R34. This size is a common choice for medium-horsepower tractors, giving you a good balance of ground contact, flotation, and traction for plowing, tilling, or hauling.
Some units at auction or in the resale market may have slightly different sizes, such as 11.2R46. These are not factory standard but show what’s possible if you need a different ground pressure or row spacing.
Make sure your rear tires match in type and size for safe operation. Wide agricultural tires help distribute the tractor’s weight evenly.
This minimizes soil compaction and provides reliable grip, even on wet or uneven ground.
Optional Duals / Tracks / Flotation Kits
Dual wheel kits can be fitted on the AGCO Allis 6690 for greater stability and flotation, especially when operating in loose or soft soils. Duals can also be helpful if you use heavy rear-mounted equipment or carry large loads.
Always follow manufacturer guidelines for safe installation. Factory options did not include track systems or flotation kits, but aftermarket conversion kits may be available for specialized uses like wet fields.
Flotation tires are wider and designed to reduce ground pressure, which helps prevent ruts and soil damage. When considering add-ons like duals or flotation kits, check compatibility with your tractor’s axle and local regulations on road transport.
Properly installed duals or flotation tires can extend the versatility of your AGCO Allis 6690.
Dimensions & Weight
The AGCO Allis 6690 offers a balanced build with well-thought-out dimensions suited for farm work and field operations. Each key measurement affects how you transport, operate, and maintain the tractor.
| Specification | Value | Notes |
|---|---|---|
| Wheelbase (2WD) | 96.4 inches (244 cm) | Stability and turning radius |
| Wheelbase (4WD) | 92.8 inches (235 cm) | Slightly shorter for 4WD models |
| Overall Length | 161 inches (408 cm) | Tip to tip |
| Overall Width (Min. Tread) | 82.4 inches (209 cm) | Narrowest working width |
| Height to ROPS/Cab | 111.2 inches (282 cm) | Top of cab/ROPS |
| Ground Clearance | 17.6 inches (44 cm) | Clearance under chassis |
| Shipping Weight | 6,724–7,385 lbs | Model and configuration dependent |
| Operating Weight (With Fluids) | Varies (typically higher) | Includes fuel, fluids, and ballast |
Wheelbase
The AGCO Allis 6690’s wheelbase measures 96.4 inches (244 cm) for 2WD and 92.8 inches (235 cm) for 4WD versions. The wheelbase is the distance between the centers of the front and rear wheels.
Wheelbase affects your tractor’s stability over rough ground. The longer 2WD wheelbase gives slightly enhanced straight-line stability.
The 4WD’s shorter base offers improved maneuverability, especially in tighter spots. A good wheelbase provides balance for implements and reduces the chance of tipping when carrying loads.
When choosing a tractor configuration, knowing the correct wheelbase can help you plan for the field conditions and types of attachments you intend to use.
Overall Length
The overall length of the AGCO Allis 6690 is 161 inches (408 cm). This is the total length from the front to the back of the tractor.
Length matters most when parking in storage spaces or transporting on a trailer. The longer frame allows for better balance when attaching large or heavy implements.
If you need to use attachments like loaders or rear equipment, knowing the overall length ensures proper fit in barn aisles, sheds, or transport vehicles.
Overall Width (Minimum Tread)
The minimum tread width, or the narrowest factory setting for the AGCO Allis 6690, is 82.4 inches (209 cm). This measurement is important for passing through tight gate openings, orchard rows, or narrow roads.
With the adjustable tread, you can sometimes make the tractor narrower or wider by moving the wheels in or out. A narrower tread is useful for row-crop work or restricted spaces.
A wider setting may give you more stability for fieldwork. Knowing the minimum width helps you avoid accidents with fences, gateposts, or other obstacles.
It also helps with planning transport and storage arrangements on your property.
Height to ROPS / Cab
The height to the top of the ROPS (Roll-Over Protective Structure) or cab is 111.2 inches (282 cm). This is the highest point on the standard model, measured from the ground up.
Height is a key factor when moving indoors or under bridges and trees. With this measurement, you can plan access to low-clearance barns or storage facilities.
You should always take height into account when attaching tools or hauling the tractor on a trailer. Exceeding clearance could damage the ROPS, cab, or building.
This dimension keeps you aware of potential clearance problems in every workspace.
Ground Clearance
The AGCO Allis 6690 has a ground clearance of 17.6 inches (44 cm). Ground clearance is the distance from the lowest part of the tractor’s chassis to the ground.
This clearance allows you to work over uneven ground or field debris without damaging the undercarriage. It’s especially useful for farms with rough terrain or stubble from previous crops.
The higher clearance also lets you cross ditches or field bumps more easily. If you operate in rocky areas or need to clear brush, having enough ground clearance reduces the risk of getting stuck or harming tractor components underneath.
Shipping Weight
The shipping weight for the AGCO Allis 6690 is between 6,724 and 7,385 pounds depending on the configuration, such as 2WD or 4WD and any installed options. Shipping weight is the bare tractor weight without fluids, ballast, or operator.
This weight affects your cost and method of delivery and influences shipping class for transport companies. You need this number for insurance, road transport regulations, and planning safe equipment moves.
When buying a tractor, knowing shipping weight helps you select the right trailer or hauler. Overloading a trailer can lead to safety hazards, so always check this weight before moving the tractor.
Operating Weight (With Fluids)
Operating weight includes the weight of the AGCO Allis 6690 tractor with standard fluids such as engine oil, coolant, hydraulic fluid, and a full fuel tank. This weight might increase more if you add wheel weights, front weights, or liquid ballast to the tires.
Actual operating weight is always higher than shipping weight. Most farms operate their tractors with all fluids topped off and sometimes carry extra equipment.
This weight can influence soil compaction in fields, and it’s critical when planning field work that requires certain axle loads. You should always know the loaded weight before operating in soft soil or using on public roads, to prevent excessive soil damage or run into road weight restrictions.
Calculating your total weight also helps you plan safe towing and storage solutions.
Fuel & Fluids
Keeping the correct fuel and fluid levels in your AGCO Allis 6690 is essential for good performance and engine health. Regular checks for diesel, engine oil, and hydraulic/transmission fluid help your tractor run smoothly and avoid problems.
| Fluid Type | Capacity | Location/Notes |
|---|---|---|
| Diesel Fuel Tank | 28.27 gallons (107.0 L) | Under cab, left side fill |
| DEF Tank | Not Applicable | No DEF system |
| Engine Oil | ≈11 quarts (10.4 L) | Front of engine, drain plug |
| Hydraulic/Transmission Oil | 15.2 gallons (57.5 L) | Central reservoir |
Fuel-Tank Capacity
The AGCO Allis 6690 uses a diesel engine with a fuel tank capacity of about 28.27 gallons (107.0 liters). You will find the fuel tank under the cab, and the fill cap is usually located on the left side of the tractor.
This high capacity allows you to run the tractor for long periods, even under heavy loads. For most work, a full tank will last you most of the day, depending on engine RPM and load.
Be sure to use clean, high-quality diesel fuel to avoid problems like clogging or poor engine performance. Keeping the tank filled also helps reduce condensation that can lead to water in the fuel.
DEF-Tank Capacity (If Applicable)
The AGCO Allis 6690 does not use a diesel exhaust fluid (DEF) system. This model predates emissions systems that require DEF, so no DEF tank or related maintenance is needed.
You do not need to purchase or refill DEF for this tractor. Emissions controls on this machine are managed without urea injection.
This makes fueling and upkeep a bit easier compared to newer models that need DEF. If you are used to operating tractors that require DEF, be aware that it is not something you need to worry about with the AGCO Allis 6690.
Engine Oil Capacity
The engine holds about 11 quarts (10.4 liters) of oil. Always refer to your operator’s manual for the exact specification and oil type.
Change the engine oil at intervals recommended by the manufacturer, checking the dipstick regularly to keep the oil between the “min” and “max” marks. Using the correct grade is important for proper lubrication, especially in cold or very hot weather.
A large oil capacity helps keep the engine cool and well-lubricated, especially during long or hard jobs. If you see contaminants or the oil looks dark, change it sooner rather than later.
Hydraulic/Transmission Oil Capacity
The hydraulic and transmission systems share a common reservoir, taking about 15.2 gallons (57.5 liters) of fluid.
Check the fluid level using the sight glass or dipstick on the rear of the tractor.
Use only the manufacturer-recommended type and check for leaks frequently.
Clean and adequate fluid is key for reliable operation of the three-point hitch, loader, and other hydraulic attachments.
Monitor fluid color and level after heavy use or if you notice changes in hydraulic performance.
Replace filters and fluid at the intervals listed in the manual or sooner if the tractor has been under heavy load or in dirty conditions.
Always check after installing any new hydraulic attachments.
Electrical System
The AGCO Allis 6690 tractor relies on a modern 12-volt electrical system for starting, running electronics, and powering vital features.
Knowing how the ground type, alternator, battery specifications, and charging output work helps you maintain good performance and reliability.
Ground Type (Negative / Positive)
This tractor uses a negative ground electrical system.
With negative ground setups, the battery’s negative terminal connects directly to the chassis and frame.
Most newer tractors—including the AGCO Allis 6690—use this design for better safety and more efficient current flow.
It’s the standard approach for modern farm equipment.
If you need to connect accessories or perform maintenance, always remember the negative terminal is connected to the tractor body.
When disconnecting the battery, start with the negative cable first.
This reduces the risk of short circuits or sparks.
Using negative ground also makes finding compatible replacement parts easier.
Add-ons like radios, lighting kits, and diagnostic tools often assume a negative-ground system.
Alternator / Charging System
The AGCO Allis 6690 comes standard with an alternator-based charging system.
The alternator turns mechanical engine energy into electrical energy to keep the battery charged and support all electrical accessories.
This system will charge the battery whenever the engine is running.
Key functions powered include gauges, the radio, lighting, and electronic controls.
If the alternator or voltage regulator fails, you may notice the battery warning light on your dash.
This means the charging system is not working and needs attention.
If left alone, you may lose power to essential tractor features.
When troubleshooting problems, always check drive belts, wiring connections, and the condition of the alternator itself.
Charging Output (Amps)
The alternator on the AGCO Allis 6690 is designed to provide a steady charge during operation.
Typical output is around 55 to 65 amps.
This amperage is enough to keep the battery charged while running common accessories, especially at working engine speeds.
The available amperage supports headlights, work lights, in-cab electronics, and engine control systems.
A bad alternator output can lead to a weak battery, especially if you use many powered features at once.
If you add more electrical accessories, make sure the alternator can handle the extra load.
Check your voltmeter or warning lights to monitor system performance.
If output drops below recommended levels or accessories dim noticeably, the charging system may need service.
Battery Voltage
The AGCO Allis 6690 uses a 12-volt electrical system for normal operation.
This is the industry standard for tractors of this size and age.
A single 12-volt battery is mounted on the machine.
This battery supplies starting power, runs computers and electronics, and supports lighting and safety systems.
Always replace the battery with an equivalent 12-volt unit, observing proper terminal orientation and ground type.
Be sure to check voltage regularly using a quality voltmeter.
If the tractor has trouble starting, check for low voltage or weak battery condition.
Do not use a 6-volt or 24-volt battery, as this may damage electrical components.
Battery CCA Rating
The most important rating for tractor batteries is Cold Cranking Amps (CCA).
For the AGCO Allis 6690, use a battery rated at least 700-900 CCA.
This rating helps the engine turn over on cold mornings or in tough conditions.
Higher CCA batteries perform well during winter starts and when extra accessories draw power at startup.
A battery that matches or exceeds these CCA values is important for starting reliability.
Consider the climate in your location when choosing a battery.
Cold weather may require batteries with even higher CCA ratings.
Replace weak or aging batteries promptly to avoid getting stranded.
Always secure the replacement firmly and double-check all cable connections.
Table: AGCO Allis 6690 Tractor Electrical System Overview
| Feature | Specification / Detail | Importance |
|---|---|---|
| Ground Type | Negative | Standard for safety, compatible with most accessories |
| Alternator / Charging | Alternator, engine-driven, regulated output | Keeps battery charged, powers electronics |
| Charging Output (Amps) | 55 – 65 Amps | Supports lighting and accessory use |
| Battery Voltage | 12 Volt | Required for starting and system functions |
| Battery CCA Rating | 700 – 900 CCA | Reliable cold-weather starts |
Key Maintenance Tips:
- Check battery connections for corrosion
- Inspect alternator belt and wiring
- Replace battery with correct voltage and CCA rating
- Use manufacturer-recommended replacement parts
Total Cost Of Ownership Metrics
When considering the AGCO Allis 6690 tractor, it’s important to review ownership expenses, including scheduled maintenance, yearly upkeep costs, depreciation trends, and fuel usage during normal work tasks.
| Metric Category | Details |
|---|---|
| Service Intervals | Engine oil: every 250 hrs; Transmission: every 500 hrs; Filters: as advised |
| Annual Maintenance Cost | Estimated $1,200–$1,800, covers parts, fluids, and labor |
| Depreciation Curve | 10–12% per year for first 5 years; slows to 5–7% per year later |
| Fuel Use @ Rated Load | Around 14.5–16.2 L/hr depending on field conditions and load |
Recommended Service Intervals
Routine servicing keeps your tractor reliable and productive.
- Engine oil and filter should be changed every 250 operating hours or once per year—whichever comes first.
- Transmission and hydraulic fluid changes are recommended every 500 hours.
- Fuel and air filters need inspection every 100–200 hours and replacement as needed.
Inspect belts, hoses, brakes, and cooling system during each oil change.
Grease fittings and universal joints at least every 50 hours, or more in harsh environments.
Always use parts and fluids that meet AGCO specifications to prevent wear and maintain performance.
Estimated Annual Maintenance Cost
Annual maintenance costs for the AGCO Allis 6690 typically range from $1,200 to $1,800.
This amount covers oil, filters, seals, hydraulic fluid, and scheduled labor.
Costs will be higher if major components need repair, but with steady upkeep, emergency repairs are less likely.
Parts are usually easy to source, which helps control expenses.
Performing minor tasks yourself also helps save money.
Factoring preventive maintenance into your yearly budget will help spread costs evenly and minimize the risk of expensive downtime.
Depreciation Curve (% Per Year)
Depreciation affects the resale value of your tractor.
A well-kept AGCO Allis 6690 loses about 10–12% of its value each year for the first five years.
After that, annual depreciation slows to around 5–7%, assuming regular maintenance and average usage.
Older tractors tend to hold value better if kept in good operating condition and with current servicing records.
Tracking depreciation helps you make informed decisions when considering upgrades or resale.
Market trends and hours of use also play big roles in final resale values.
Fuel Consumption @ Rated Load (L Hr⁻¹)
Fuel costs form a major part of annual operating expenses.
The AGCO Allis 6690 uses a 4.0L 4-cylinder diesel engine that runs efficiently at full load.
At rated PTO output, fuel consumption is around 14.5 to 16.2 liters per hour.
Differences depend on workload, terrain, and operator habits.
Using clean filters and maintaining tire pressure can help reduce total fuel use.