10 Common John Deere 6400 Problems (2023)

It may be a hectic day for you on the farm as your John Deere 6400 troubling you. We’re aware of this type of problem and we’re determined to provide you with the solution. 

So, what are the John Deere 6400 Problems?

Overheating and starting problems are the most common engine problems with the John Deere 6400 tractor. Additionally, it’s possible to experience slipping gears and hard shifting in the transmission. SCV and hydraulic problems may also occur with this tractor. In most cases, these issues are fixable with proper maintenance and repairs.

This is just an overview. Just jump into the section for a complete solution. 

John Deere 6400 Engine Problems

Problem  Reason  Solution
Engine Not Starting Faulty starter motor Replace the starter motor. 
Engine Overheating Radiator blockage Cleaning radiator.
Low coolant levels Refilling coolant.

Problem 1: Engine Not Starting

It has come to our attention that there are instances of difficulty in starting the engine on the John Deere 6400 tractor.

While there may be various causes for this issue, we will focus on the most prevalent reason in this discussion.

Reason: Faulty Starter Motor

When the key is turned to the “start” position, the starter motor turns the engine over. The starter motor may not generate enough power to turn the engine over if it’s faulty. Engines can be prevented from starting due to this.

Solution:  Replace the Starter Motor

Tractor starter motors can be replaced relatively easily, but they do require some mechanical knowledge and experience. To get started, you’ll need the following tools:

  • A new starter motor 
  • A wrench set 
  • A screwdriver

Here is a step-by-step guide on how to replace the starter motor in a tractor:

Step 1: Put the parking brake on the tractor and park it on a flat, level surface.

Step 2: Remove the negative battery cable from the battery to prevent an electric shock.

Step 3: Locate the starter motor, which is usually located in front of the flywheel. Use a wrench to uncover the shields that are blocking access to the starter motor.

Step 4: Disconnect the starter motor’s electrical connections. Typically, this includes the main power wire and the solenoid wire.

Step 5: Take off the mounting bolts that hold the starter motor in place. After that, carefully remove the starter motor.

John Deere 6400 Engine Problems
Source: The Farming Forum

Step 6: Be sure to clean the mounting surface and lubricate the gears of the starter motor before installing it. And then mount the new starter motor with mounting bolts in the same position as the old one.

Step 7: Connect the starter motor’s electrical connections again.

Step 8: Replace any covers or shields that were removed earlier.

Step 9: To check whether the starter motor is working properly, reconnect the negative battery cable to the battery and start the tractor. If it doesn’t work, recheck everything installed properly. 

If you feel unfamiliar with these processes, consult a professional automobile mechanic for this task. 

Problem 2: Engine Overheating

John observed the overheating issue is also common for the John Deere 6400. There are multiple reasons behind this issue. But blocked radiator and low coolant level are the most common reasons. So let’s discuss them below. 

Reason 1: Radiator Blockage

Overheating can be caused by a blockage in the radiator, which prevents coolant from flowing through the engine. When debris, such as leaves or dirt, accumulates in the radiator, it restricts the flow of coolant. 

Furthermore, corrosion and rust can also cause radiator blockages. Severe blockages can cause the engine to overheat and potentially damage it.

Solution: Clean Radiator

Here are step-by-step processes for cleaning your radiator:

Necessary Tools: 

  • A wrench set 
  • A piece of left-out fabrics
  • Cleaning solution 
  • Pressure washer

Step 1: Turn off your tractor’s engine and park it on a level surface. Make sure the engine is completely cooled before proceeding.

Step 2: Carefully remove the radiator cap as the coolant inside is still hot.

Step 3: Using a hose or pressure washer, clean the radiator with a radiator cleaning solution or water and baking soda. Ensure that any debris or buildup is removed.

Step 4: Check the radiator for leaks or damage. You may need to repair or replace your radiator if you notice any leaks or damage.

Step 5: After cleaning the radiator, replace the radiator cap and refill the coolant.

Step 6: Run the engine for a few minutes to circulate the coolant and check for leaks.

It may be necessary to take the tractor to a professional service center for further diagnosis and repair if the problem persists after cleaning the radiator.

Reason 2: Low Coolant Levels 

John Deere 6400 engines can overheat if they have low coolant levels because the coolant removes heat and maintains the engine’s temperature.

Low coolant levels prevent the engine from effectively transferring heat away from it, causing the temperature to rise and potentially overheating the engine. 

Solution: Refill Coolant

To refill the coolant in your John Deere 6400 tractor access the radiator and open the coolant pump cap. Using a filter, refill the coolant.

Make sure the coolant overflows from the pump. In order to ensure the proper circulation of coolant, start the engine for a while after refilling and closing the cap.

John Deere 6400 Transmission Problems

Problem Reason  Solution
Slipping Gears Low transmission fluid  Refilling transmission fluid.
Hard Shifting  Worn linkage Replacing Linkage.
Worn Bushings Replacing Bushings.
Shuttle Shift Not Engaging Low fluid levels in the transmission Refill transmission fluid.
Clogged or dirty filters Unclog the filters.

Problem 3: Slipping Gears

As tractors are used in dirty circumstances for heavy duty so there is a chance for slipping gear due to that. Because this type of environment triggers the factors that result in slipping gear.  

Reason: Low transmission Fluid

A tractor’s transmission fluid lubricates the gears, allowing them to shift smoothly. Low or dirty fluid can cause the gears to slip, resulting in a loss of power or the tractor moving in an unintended direction. 

Solution: Refill Transmission Fluid

Follow these steps to refill the transmission fluid in your John Deere Track tractor. 

Step 1: To check the transmission fluid level, locate the dipstick and remove it.

Step 2: Through the dipstick tube, add the appropriate type of transmission fluid if the level is low. Consult the tractor’s operator manual for the correct type and amount of fluid.

Step 3: Start the tractor and let it run for a few minutes after replacing the dipstick.

Step 4: Check the fluid level again after the tractor is running and add more fluid if necessary.

Step 5: Make sure the fluid reaches the “full” mark on the dipstick by repeating this procedure.

Step 6: Ensure the fluid level remains at the proper level after refilling and checking it regularly.

It may be necessary to drain the transmission and refill it with fresh fluid if the transmission fluid is dirty. If you need specific instructions, consult your tractor’s operator manual.

Problem 4: Hard Shifting Gear

Hard shifting refers to the difficulty in shifting gears in a tractor or other vehicle with a manual transmission. It can be caused by different factors. Let’s see what they are.

Reason: Worn linkage

When a linkage is worn, the transmission cannot engage gears smoothly, resulting in hard shifting. The linkage controls the movement of the gears by connecting the transmission to the gearshift lever.

When the linkage wears out, it can become loose or misaligned, making gear shifting difficult. Hard shifting may result from grinding or improper engagement of the gears.

Solution: Replacing Linkage

If the linkage in the transmission is worn then you need to replace it. Replacing gear linkage is a hard task. Many parts need to be removed and reinstalled.

So to replace the transmission linkage take assistance from an automotive expert. 

Reason: Worn Bushings

Having worn bushings in the transmission of a tractor can cause hard shifting. In tractors, bushings act as bearings between the transmission and the frame.

By supporting and aligning the transmission, they make it move smoothly.

As bushings wear out, they can become loose and misaligned, causing the transmission to bind or stick. Transmission damage can result from this as well as difficulty shifting gears. 

Solution: Replacing Bushings

Some mechanical knowledge and special tools are required to replace bushings on a tractor’s transmission. So it’s recommended to contact an expert to replace the transmission bushing properly. 

Problem 5: Shuttle Shift Not Engaging

If the shuttle shift is not engaged, the tractor will be unable to shift between forward and reverse gears, which makes certain tasks difficult or impossible. There can be several reasons behind it. We’ll discuss that here. 

Reason 1: Low Fluid Levels In The Transmission

A shuttle shift is a feature found on some tractors that allows the operator to shift between forward and reverse gears without using the clutch pedal.

Transmission gears can bind or stick if the transmission fluid level is low, resulting in a lack of lubrication.

Consequently, the shuttle shift may have difficulty engaging, resulting in a delay or failure to shift forward or reverse. 

Reason 2: Clogged Or Dirty Filters

In tractors, clogged or dirty filters can prevent the shuttle shift from engaging because they restrict fluid flow to the transmission.

When the transmission filter is clogged, the transmission can bind or stick, making it difficult to shift gears. Transmission damage can also result from this.

Furthermore, contaminants in the fluid can bind the gears and make shifting difficult. Transmission components can also suffer from increased wear and tear as a result.

Solution: Unclog The Transmission Filters

Here is a general step-by-step procedure for unclogging the filter:

Tools Needed: 

  • A socket 
  • Filter removal tool
  • Soft bristle brush

Step 1: Find the transmission filter. It’s usually located near the transmission or in the oil pan.

Step 2: Drain the transmission fluid into a suitable container by removing the drain plug.

Step 3: Remove the old filter with a filter removal tool. Remove dirt and debris from the area surrounding the filter. With a soft-bristled brush, inspect the filter for debris or clogging and clean it.

Step 4: Make sure the filter is properly seated and tightened to the correct torque.

Step 5: Replace the drain plug and fill the transmission with the correct type and amount of fluid as directed in the tractor’s manual

Step 6: Run the tractor for a few minutes, then check the fluid level and add more if necessary.

Check the fluid level regularly after refilling to ensure it remains at the appropriate level.

John Deere 6400 SCV Problems

The John Deere 6400 tractor is equipped with a Selective Control Valve (SCV) that controls the flow of fluid to the tractor’s implements, allowing the operator to raise, lower, and control the speed of the implement. 

Problem Reason  Solution 
Leakage in SCV Worn or damaged seals Replaces Seals.
Overheating of SCV Clogged cooling fan  Unclog the cooling fan.

Problem 6: Leakage in SCV

In John Deere 6400 tractors, leaking seals in the Selective Control Valve (SCV) can cause fluid leakage, resulting in reduced functionality, power, efficiency, control, and increased wear and tear, which can cause costly repairs or failure. 

The worn or damaged seal is responsible for that. We’ll discuss that here along with the solution.

Causes: Worn Or Damaged Seals

In a Selective Control Valve (SCV), worn or damaged seals can cause leakage, resulting in loss of pressure and control.

The seals prevent fluid from leaking out of the valve, and when they become worn or damaged, they can no longer do their job.

In a valve, fluid pressure pushes against the seal, and if the seal is worn or damaged, it can’t withstand the pressure and leaks.

Consequently, the internal components of the valve can become contaminated with dirt and debris, causing further damage.

Solution: Replace Seals

It’s a highly complicated task to replace the seal of a selective control valve. Replacing the SCV valve requires a high knowledge of automobiles. So, we always recommend contacting an expert to do this task. 

Problem 7: SCV Overheating

Sometimes you may find that the SCV unit’s excessively overheating. Some typical issues are responsible for this issue. So, let’s discuss the most probable reason below. 

Causes: Clogging of Cooling Fins 

SCV overheating can occur when the cooling fans that are responsible for keeping the valve cool become clogged with dirt, dust, or debris.

The fins are designed to keep the valve cool by blowing air over it, but if they become clogged, they can no longer effectively cool the valve.

Solution: Clean Cooling Fins

To prevent the Selective Control Valve (SCV) in a John Deere 6400 tractor from overheating, it’s important to regularly clean the cooling fins. The procedure for cleaning the cooling fins involves the following steps:

Necessary Tools: 

  • A soft-bristled brush
  • Air compressor

Step 1: Place the tractor on a level surface, engage the parking brake, and locate the SCV cooling fin.

Step 2: Gently remove any dirt, dust, or debris that has accumulated on the fins with a soft-bristled brush.

Step 3: Blow out any remaining debris from the fins with compressed air.

Step 4: Check the fines for damage or bending. If the fins are damaged, they may need to be replaced.

Keep the fins clean and prevent overheating by repeating the cleaning process regularly.

John Deere 6400 Steering Problems 

Problem Reason  Solution
Wide Turning Radius Faulty Suspension Realign Front End Suspension.

Problem 8: Wide Turning Radius

When the John Deere 4600 tractor faces a wide turning radius, it means that the tractor is unable to make tight turns or maneuver in tight spaces as easily as it should. The faulty suspension is responsible for this issue. 

Let’s see how the faulty suspension causes a wide turning radius. 

Reason: Faulty Suspension

When the suspension on a John Deere 4600 tractor is misaligned, it can result in a wider turning radius.

A misaligned suspension can cause the wheels on one side of the tractor to be out of alignment with the wheels on the other side. 

It makes it difficult to turn a tractor in a tight radius if the tractor pulls to one side. A misaligned suspension can also cause uneven tire wear, contributing to a wider turning radius. 

Solution: Realign Front-End Suspension

Realigning the front-end suspension on a John Deere 6400 tractor involves several steps:

Step 1: Raise the front of the tractor with a jack or lift.

Step 2: The next step is to remove the tractor’s wheels. Remove the wheels and inspect the suspension components, such as the steering linkage, ball joints, and tie rod ends, for wear or damage. In case of wear or damage, replace them as needed.

Step 3: it’s important to check the alignment of the wheels. The distance between the wheels and the front of the tractor should be measured. There should be an equal amount on both sides. Tie rod ends or steering linkage may need to be adjusted if the measurement is not equal.

Step 4: Lower the tractor back to the ground after reinstalling the wheels. Last but not least, test drives the tractor to ensure the alignment is correct and the steering is smooth.

This process should be performed by a qualified technician who is familiar with the tractor and has the right tools and equipment.

John Deere 6400 Hydraulic Problem

Problem  Reason Solution
Difficulty in lifting the implement Worn or damaged lift arms replace worn or damaged lift arms.
leak in the hydraulic system fix any leaks in the hydraulic system.

Problem 9: Difficulty In Lifting The Implement

Difficulty in lifting the implement can prevent or hinder the completion of the task that the implement is designed to accomplish.

Different reasons can be responsible for this issue. So let’s discover the reasons and solutions here. 

Reason 1: Worn Or Damaged Lift Arms

Worn or damaged lift arms can cause difficulty in lifting an implement by reducing the strength of the lift arms.

The lift arms may bend or break, making it difficult to attach or detach the implement, reducing pressure on the lift arms, and preventing lifting to the desired height. 

For proper operation and to prevent difficulty lifting the implement, it’s important to inspect and maintain lift arms regularly.

Solution: Replace Worn Or Damaged Lift Arms

Replacing the lift arm is a difficult and heavy-weight task. It needs expert professionals, so we recommend going for a service to replace lift arms.

Reason 2: Leak In The Hydraulic System

Lifting an implement can be difficult when there is a leak in the hydraulic system since it reduces the pressure on the lift arms.

If there is a leak in the hydraulic system, the pressurized fluid can escape, reducing the pressure available to lift the implement. 

As a result, the lift arms may struggle to lift the implement to the desired height or may not be able to lift it at all.

Furthermore, it can reduce the oil level in the system, resulting in damage to the pump, valves, and other system components. 

Solution: Fix Any Leaks In The Hydraulic System

In order to fix leaks in the hydraulic system of a John Deere tractor, follow these steps:

Step 1: Look for signs of damage or wear on the hydraulic hoses, fittings, and connections in order to locate the source of the leak. Look for leaks in the system and check the oil level.

Step 2: Replace any worn or damaged hoses and fittings. To ensure proper fit and function, use only genuine John Deere parts. Make sure any loose connections are tightened.

Step 3: Inspect the seals and O-rings of the system for any damage or wear. Make sure there are no leaks in the system, which may cause the implement to be difficult to lift.

Step 4: Afterwards, bleed the air from the system by opening the bleed screw on the lift cylinder or the remote valve.

Step 5: By operating the lift controls, check for leaks, unusual noises or vibrations, and difficulty lifting the implement.

John Deere 6400 Electrical Problems

Problem Reason Solution
Fuel Gauge Not Working Faulty Sensor Replacing the Sensor.

Problem 10: Fuel Gauge Not Working

The fuel gauge visualizes the fuel level in the tank. If the fuel gauge doesn’t work then you won’t be able to see the fuel level in your vehicle.

A number of reasons might be responsible for this issue. Here we’ll discuss the most common reason for the John Deere 6400 tractor. 

Reason: Faulty Sensor

Fuel gauges can malfunction if there is a faulty sensor in the fuel system, such as a fuel level sensor. The sensor measures fuel levels in the tank and sends that information to the gauge.

It’s possible that the gauge will not display the correct fuel level if the sensor is not working correctly. 

Solution: Replace the Sensor

Depending on the severity of the problem you might need to replace the sensor. Replacing the sensor is a highly technical task. So it’s better to consult an automobile expert for this type of task. 


Well, this was all about the John Deere 6400 problems. Hopefully, we’ve covered your cherished query.

It’s always better to consult an expert before attempting any DIY task if you don’t have enough technical knowledge regarding this issue. 

Anyway, thanks for reading!

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