John Deere 850 Problems (With Optimal Solutions)

The compact tractor has been popular across the world for more than three decades. But, they also have some problems. Maybe you are about to buy one or perhaps you are already using one! 

But, shouldn’t you know the John Deere 850 problems?

The John Deere 850 tractors have some common problems in the engine, transmission, steering, and hydraulic system. Engine problems include overheating, lack of power, and problems with the starter and fuel system. Sometimes, it’s hard to change gears and steer the tractor.

The article is focused on the solutions to all the problems of the John Deere 850 tractor. It clarifies the advantages and disadvantages of the popular compact tractor.

John Deere 850 Engine Problems 

The 3-cylinder Yanmar engine is very robust and popular for longevity. However, most of the John Deere 850 tractor problems come from the engine.

Problem Reason Solution
Overheating Clogged radiator, a faulty thermostat Clean the radiator, and troubleshoot the thermostat.
Lack of Power Clogged air filter, faulty fuel pump, bad carburetor  Clean the air filter, and troubleshoot the fuel pump and carburetor.
Starter Problems Bad starter motor, defective starter solenoid,  Troubleshoot the starter motor and the starter solenoid.
Fuel System Issues Clogged fuel filter, faulty fuel pump, defective fuel line Clean the fuel filter, and troubleshoot the fuel pump and fuel line.

Problem 1: Engine Overheating

Many owners complain John Deere 850 doesn’t work properly due to an overheated engine. In most cases, a clogged radiator and malfunctioning thermostat is the problem.

Solution 1: Clean the Radiator

The radiator plays a key role to keep the engine cool. It stores coolant agents that flow when the thermostat detects excessive heat. If the radiator is clogged the coolant fluid cannot circulate.

Solution 2: Troubleshoot the Thermostat

It is the thermostat that detects excessive heat in the engine. The cooling process starts after the detection. The system cannot know when to start cooling the engine if the thermostat is faulty. 

Check if you can fix the thermostat. Or else, change it.

Problem 2: Lack of Power

The John Deere 850 tractor’s engine can produce up to 25 hp of power. If you think it lacks power, first make sure you are not putting excessive load on it.

To be sure about the power generation, you need to schedule a dynamometer test for the engine. However, you may try the following solutions to fix it yourself.

Solution 1: Clean the Air Filter

The engine produces power by using a perfect mixture of air and fuel. If the air filter is clogged and airflow is obstructed, the engine will underperform. You can easily detect a clogged air filter from its looks.

Solution 2: Troubleshoot the Fuel Pump

  • Step 1: Test the fuel pump fuse. Locate the fuse in the fuse box. Pull out the fuse and check for any burn or damage signs. Replace the fuse if it is faulty. If the fuse burns repeatedly, schedule an auto workshop service.
Test the voltage of the fuel pump
[Source: WikiHow]
  • Step 02: Test the voltage of the fuel pump using a multimeter. If there is not enough voltage in the fuel pump, check the relay circuit. Replace the voltage relay circuit of the fuel pump.
  • Step 03: If the problem is still there, perform a fuel pressure test. Attach a fuel pressure gauge to the fuel pump test point, near the fuel injectors. Tell someone to rev the engine and monitor the pressure gauge. If there is no or little change in the gauge, the fuel pump is faulty. Replace it.
perform a fuel pressure test
[Source: WikiHow]

Problem 3: Engine Starter Problems

Sometimes, John Deere 850 doesn’t start at all! In that case, the first thing to check is the starter motor. The second thing to check would be the starter solenoid.

Solution 1: Troubleshoot the Starter Motor

  • Step 01: Check the voltage level of the starter motor using a multimeter. An uneven resistance or no resistance at all indicates a faulty starter motor. In that case, replace the starter motor.
  • Step 02: Check the starter motor bearings. Lubricate the bearings if they cannot move freely. If lubrication doesn’t help, replace the bearings. 
  • Step 03: If the voltage level and the bearings are okay, the starter is faulty. Replace the starter motor.

Solution 2: Troubleshoot the Starter Solenoid 

  • Step 1: The starter solenoid is located right on top of the starter motor. Turn the ignition key on and try to hear the sound of the starter solenoid. Expect to hear a clicking noise. If there is no noise, the solenoid is damaged. Change it.
  • Step 2: If the solenoid is okay, check the battery for any malfunction. Use a multimeter to check the voltage level of the battery. If the voltage level is less than 12 volts, charge the battery or change it.
Troubleshoot The Starter Solenoid
[Source: Samarins]

Problem 4: Fuel System Issues

John Deere 850 tractors can also have problems with their fuel system. The fuel filter, fuel pump, and fuel line sometimes become faulty. As a result, the engine doesn’t get enough fuel to produce power.

Solution 1: Troubleshoot the Fuel Filter

A fuel filter has a crucial role in engine operation. It stops any debris, dirt, and other foreign particles of the fuel to do harm the engine.

Solution 2: Troubleshoot the Fuel Pump

Check for any problems in the fuel pump and resolve them as mentioned above. If the engine still doesn’t get the right amount of fuel try the rest of the solutions.

Solution 3: Troubleshoot the Fuel Line

Sometimes, the engine doesn’t get enough fuel for a defective fuel line. Use this video tutorial to troubleshoot the fuel line: 

John Deere 850 Transmission Problems 

The John Deere 850 tractor can have transmission problems too. It is very common for the tractor to have a difficult gear shift. 

Problem Reason Solution
Difficult Gear Shift Faulty transmission linkage, defective gears Fix the transmission linkage, and troubleshoot the gears.

Solution: Troubleshoot the Transmission 

  • Step 1: Check for any leaking of the transmission fluids. Find and fix the leaking point.
  • Step 2: Check the level of the transmission fluid. Top up the transmission fluid if the level is low.
  • Step 3: Check if the transmission fluid color has turned lighter or pink. It indicates the presence of water. Drain out the transmission fluid and refill it.
  • Step 4: Check the transmission linkage for any visible damage. Repair or replace it if it is damaged or worn out.
  • Step 5: Remove the transmission cover and check the gears and the bearing balls. Lubricate them. Change them if they are damaged or worn out.

John Deere 850 Steering Problems 

Some John Deere 850 owners find problems in the steering of the tractor. Sometimes, it becomes challenging to steer the tractor smoothly. In other cases, the steering doesn’t respond at all.

Problem Reason Solution
Difficult or Non-responsive Steering Problematic steering gear or steering linkage Troubleshoot the steering gear and linkage.

Solution: Difficult or Non-Responsive Steering

  • Step 1: Check the pressure of the tires. Correct the pressure if it is low.
  • Step 2: Look for friction in the linkage, steering gearbox, or ball joints. Lubricate the components to fix the friction.
  • Step 3: Check if the steering gear is too tight. Loosen the gear if it is too tight. 
  • Step 4: Check if the wheel alignment is correct. Correct the alignment if there is any deviation.
  • Step 5: Test the power steering pump for any defects. Fix or replace the steering pump if necessary.
  • Step 6: Check whether the power steering pump belt is loose or not. Adjust the steering pump belt if required.
  • Step 7: Check the steering fluid level. Top up the steering fluid if the level is low.

John Deere 850 Hydraulic Problems

Hydraulic problems are not rare for the tractor. Some common John Deere 850 hydraulic problems include difficult movement of the loader and carrying loads.  

Problem Reason Solution
Difficult Lifting & Lowering of Attachments Faulty hydraulic pump and hydraulic line Troubleshoot the hydraulic pump and line.

Solution: Troubleshoot the Hydraulic System

  • Step 1: Check for any leakage of the hydraulic fluid. If you find any leakage, fix it.
  • Step 2: Listen carefully for any unusual noise. It indicates an airlock in the steering. Drain out the fluid to remove the air.
  • Step 3: Look for any dirt or debris in the steering system. Drain out the fluid and clean the steering system.
  • Step 4: Check if there is any physical damage in the hydraulic pump or the line. Fix the damage or replace the pump and/or line if the damage is unrepairable. 
  • Step 5: Check all four couplers of the loader. Open the couplers, clean them, and reattach them.

Pros & Cons of John Deere 850

The last John Deere 850 was made in 1989. The tractor has been popular for three decades in the small tractor category. 

Advantages of John Deere 850 Disadvantages of John Deere 850
Quality Engine Inefficient Loaders.
Great Transmission Uncomfortable Seat.

Advantages of John Deere 850

The John Deere 850 tractor has a few advantages over its competitors on the market. The biggest selling point of the tractor is its efficient engine and transmission.

  • Quality Engine: The engine of the John Deere 850 is made by a famous Japanese company- Yanmar. The 3-cylinder diesel engine can produce up to 25 hp of power. John Deere 850’s engine performance is great, considering its price category. 
  • Great Transmission: The transmission of the John Deere 850 has eight forward gears and two reverse gears. The maximum speed of the tractor is 11.7 miles per hour. The transmission works smoothly for a long period with proper maintenance.

Disadvantages of John Deere 850

The John Deere 850 tractors have an ill reputation in a few areas. The loaders, the steering, and the seat of the tractor are considered to be its weaker features.

  • Inefficient Loaders: Many owners claim that the loaders often disappoint them. On many occasions, the loaders fail to lift and carry a minimum load.
  • Uncomfortable Seat: The seat of the John Deere 850 is not popular among its users for comfort. The space for legs can seem too small if you are a big fellow. 


What engine is in John Deere 850?

John Deere 850 has a 3-cylinder diesel engine. The model of the engine is Yanmar 3T80-J. It is produced by a Japanese company- Yanmar. The maximum hp of a John Deere 850 tractor is 25.

How Big is an 850 John Deere?

The height of an 850 John Deere is 50.8 inches and the width is 53.3 inches. The length of the tractor is 117.7 inches. It has a wheelbase of 64 inches.

When The Last John Deere 850 Was Made?

John Deere 850 was last made in 1989. The first edition of this popular compact tractor came into the market in 1978.


Now you know about almost all the John Deere 850 problems. Let us know if you found the solutions of this article to be helpful.

Let us know if you are facing any different problems with the tractor. We will let you know the solution to that problem too.

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