John Deere 4020 Problems (Tips for Resolving)

There are many existing problems with the John Deere 4020; from easy to complex. These problems can make your experience with the tractor dull. 

But hey, I am here to help you get to the solutions. Still, you need to know the problems in detail to solve them.

The John Deere 4020 may experience problems regarding the hydraulic, clutch, steering, powershift, and PTO mechanisms. Worn-out, damaged, and loose components and linkages are the majority of reasons for the problems. But they can be easily fixed by repairing, cleaning, and replacing the problematic component. 

This information just sums up the entire article. You will need more information to be able to troubleshoot the problems. Read till the end to know more.

John Deere 4020 Hydraulic Problems

Problems Reasons Solutions
Loss of power steering upon pressing clutch Worn-out charge pump

Worn-out hydraulic filter

Replace the charge pump.

Replace the hydraulic filter.

Noisy hydraulic pump Objects inside pump’s inlet

Too much air inside the pump

Clean and replace the hydraulic pump.
Low hydraulic pressure Leaks in the hydraulic system

Worn-out hydraulic filter

Stuck control and priority valve

Repair and replace the leaks. 

Replace the hydraulic filter.

Decouple the actuator from the valve body.

Problem 1: Loss of Power Steering Upon Pressing Clutch

During this problem, you’ll lose the power steering and power brakes upon pressing the clutch. It does recover after a few seconds but the problem arises again in the next clutch activation. 


Worn-out charge pumps are the first reason behind this problem. When the charge pump at the back of your tractor fails to work, the clutch malfunctions simultaneously. 

Secondly, worn-out hydraulic filters can cause this issue. Since the clutch is related to the hydraulic mechanism, a working filter is essential. 


Start solving this problem by inspecting your charge pump. If the tractor’s charge pump isn’t working, replace it. 

After that, check the filters of the hydraulic system. If the hydraulic filters are clogged or too dirty, replace the filters. 

Problem 2: Noisy Hydraulic Pump

In general, hydraulic pumps do not make an absurd amount of noise. But when this problem occurs, the pump can get loud!


If there are other objects blocking the mechanism of the hydraulic pump, it can make noises. 

Another reason can be the excess trapped air inside the pump. It creates a cavity which later creates whining noises. 


To solve this issue, clean the inlet of the pump itself. Follow the steps mentioned below:

  • First, shut down the JD 4020, remove the pump power source, and drain the entire pump. 
  • Then, clean the inlet of the pump by using a tube brush and some soap water. 
  • Afterward, flush the pump with some low-viscosity fluid.
  • After that, bleed the pump and fill it up with hydraulic oil.
  • Finally, start your tractor and let it run for a few minutes. 

Observe the pump for sound. The pump is now clean and cavity-free, so the sound should be gone now.

Problem 3: Low Hydraulic Pressure

The predetermined amount of hydraulic pressure of the John Deere 4020 is about 2200 PSI. Any lower PSI can indicate a shortage of hydraulic pressure in the system.  


Firstly, this issue may be caused by hydraulic leaks in the hydraulic lines. Leaks prevent the hydraulic system from working correctly.

Second, this can be brought on by hydraulic system filters that are worn out. If the filters don’t work, the hydraulic system won’t get enough power. 


Examining the hydraulic pipes should be the first step in solving this issue. If you do manage to see any damage or leaks, replace the hydraulic pipes. 

The hydraulic filters need to be checked as well. The filters must be replaced if they are worn out.

Finally, inspect the control valve and the priority valve as well. If they are stuck, just decouple the actuator from the valve body.

John Deere 4020 Starting Problems

Problems Reasons Solutions
Slow start/engine not starting Bad battery

Bad cable connections

Bad starter

Recharge and replace the battery.

Clean and replace the cable connections.

Replace the starter.

Problem 1: Slow Start/Engine Not Starting

When the tractor doesn’t react to the ignition or starts really slow, it’s a serious problem.


The first reason for this problem is a bad battery. If the battery is out of charge or has gone bad, the engine won’t start.

The 2nd reason behind this problem is bad cable connections. Sometimes the heat and dirt inside the engine mess up the cable connections. In turn, the cables fail to supply power and the engine starts really slow. 

The third and final reason is a bad starter. Starters go bad after reaching a certain milestone. Without a properly working start, the engine might have a delay in starting.


To start off, check your battery. Try charging it and starting the engine again. If it starts slow or fails to start, the battery has gone bad. Replace the battery with a new 12V battery

After that, check the cable connections. Clean the connections first. Attach any connection that was loose/unplugged (if any). If you see any damaged cables, replace that specific wire.

At last, inspect the starter. If the starter has gone bad, replace the tractor’s starter with a new one.

John Deere 4020 Clutch Problems

Problems Reasons Solutions
Stiff clutch Rusty clutch

Unadjusted clutch linkages

Unblock the clutch and apply oil.

Problem 1: Stiff Clutch

When you have to push down harder than usual on the clutch, that’s a stiff clutch issue. It can be hard to shift gears when this issue exists.


The most common reason for this issue is a rusty clutch. Rust can oxidize the outer layer of the clutch and increase friction.

Another reason for this problem is unadjusted clutch linkages. The clutch may slip stiff when the clutch linkages aren’t adjusted properly.  


For the first solution, you have to get rid of the rust on the clutch. To do that:

  • Firstly, go under the tractor. 
  • Then, apply some penetrating oil on a wire wool and start rubbing the clutch of your tractor. 
  • Finally, get rid of the remaining oil on the clutch. You may use a clutch cleaner to do so. Apply some of it on a soft cloth and rub your clutch again.

The second solution is regarding freeing the stiff clutch. To free the clutch properly, follow the steps below:

  • First, set the tractor to its highest gear.
  • Then, raise the plow if you have it hitched.
  • After that, put your transmission in 5th and turn off the neutral safety switch.
  • Then, start the tractor again and do some plowing with it.

After plowing for 15-20 mins, your clutch should break free.

John Deere 4020 Clutch Problems

John Deere 4020 Steering Problems

Problems Reasons Solutions
Steering wheel too stiff Low steering fluid

Damaged steering pump

Worn-out power steering

Refill steering fluid.

Repair steering pump.

Replace power steering.

Front wheel turns left/right after ignition Damaged steering valve 

Damaged steering box

Repair or replace steering valve.

Repair or replace damaged steering box.

Problem 1: Steering Wheel Too Stiff

The ‘stiff’ steering wheel of the JD 4020 requires more force the turn than usual.


The 1st reason behind this problem is low steering fluid. The steering wheel rod isn’t lubed enough because there’s not enough steering fluid.

The 2nd reason is a damaged steering pump. A damaged pump hinders the free movement of your steering wheel. 

The 3rd reason behind a stiff steering wheel is the power steering being worn out.


The first thing you have to do is check the level of steering fluid in your JD 4020. If it’s too low, add some more fluid to the tank. 

Secondly, inspect the steering pump. You can notice delayed response and weird noises coming from it if it’s damaged. The damaged steering pump needs to be replaced.  

Finally, check out the power steering. With time, the power steering may wear out. If that’s the case, replace it.

Problem 2: Front Wheel Turns Left/Right after Ignition

After starting the tractor, you may notice the front wheel turning left/right on its own. The balance of the tractor is off when this happens.


Firstly, defective steering valves can cause this problem. Valves are responsible for diverting the steering fluid into the steering cylinder. So even if you have the required amount of steering fluid, this may arise for the valve. 

Secondly, a damaged steering box can cause this issue. The linkages and the bolts of the steering box may have worn out or come loose. 


Start solving this issue by checking the valve. If the valve is repairable, do it. If not, replace it. 

Another thing you have to do is check the steering box. Generally, the tractor should have 4 bolts on the front. If the bolts have become loose, tighten them firmly. However, if you see any damage, try repairing or replacing it.

John Deere 4020 Powershift Problems

Problems Reasons Solutions
Inconsistent reverse  Worn-out shift linkages

Weak transmission

Replace the shift linkages.

Service the transmission.

Park not holding the tractor Damaged shaft or spring

Park cable too long

Replace the shaft and the spring.

Shorten the park cable.

Problem 1: Inconsistent Reverse

Due to this problem, the JD 4020 might feel inconsistent while in reverse gear. This usually ends up delivering a jerky feeling to the driver.


The first reason behind this problem is worn-out linkages. When linkages are worn out, the whole mechanism fails to execute properly.

The second reason is weak transmission. Over time, the transmission of a tractor may get weak. 


To solve this problem, firstly, you need to check the shift linkages. If they’re worn out, replace them immediately. 

Secondly, you have to service the transmission system. It can be done in the nearest mechanical store.

Problem 2: Park Not Holding the Tractor

Sometimes when you park your JD 4020, the wheels may still rotate. It can be very dangerous as your tractor won’t be stationary where you park it! 


The first reason behind this problem is a faulty shaft or spring. 

The 2nd reason behind this issue can be a long park cable. A parking cable longer than needed can actually eliminate the precision in parking.


Firstly, you need to replace the shaft and the spring. Check for damages first, if it’s damaged, replace it.  

Then, you must check the park cable length. To find the park cable, open the hood cowl on the back of the John Deere 4020. You can see the park cable there. If after parking it’s not tight, tighten it by shortening it. 

John Deere 4020 Injection Pump Problems

Problems Reasons Solutions
Fuel not getting to the injectors Damaged fuel pump

Misadjusted pressure of injector pump

Fuel lines leaking/damaged

Defected injector nozzles

Rebuild the pump.

Adjust the pressure of injector pump.

Clean and replace the fuel lines.

Clean and replace injector nozzles.

Problem 1: Fuel Not Getting to the Injectors

When the fuel fails to get to the injector, the engine has ignition issues. It can be frustrating when operating the tractor.


Firstly, the fuel pump might be damaged. As a result, the fuel might not be pumped into the engine.

Secondly, the pressure of the injector pump might be misadjusted. Without minimum pressure, the fuel can’t run through the injector lines.

Thirdly, the nozzles of the injector might be defective. Defected nozzles act as a wall for the fuel. 

Finally, the fuel injector lines may be leaking. So even if the fuel is being pumped, it can’t reach the engine.


To solve this issue, first, check the fuel pump. If the pump is not working, rebuild it as soon as possible. 

Then, adjust the pressure of the fuel pump. For adjusting, follow the steps below:

  • First, remove the top cover and remove the throttle linkages.
  • Then, you’ll see 2 Allen screws under the engine. To work with the screws, turn the engine over.
  • After that, turn the two screws clockwise to decrease pressure and counter-clockwise to increase pressure. Turn both screws equally and adjust the pressure till you can see the fuel pump working.

After that, clean the nozzles. If the nozzles are blocked or damaged in any way, replace them. 

At last, clean the fuel lines and let the pump do its work. If the fuel doesn’t flow through the lines, replace them.

John Deere 4020 Diesel Hard Starting Problem

Problems Reasons Solutions
Diesel hard starting Restriction in the exhaust pipe 

Clogging in fuel tank

Worn out fuel filter

Clean the exhaust pipe. 

Bleed the tank.

Replace the fuel filters.

Problem 1: Diesel Hard Starting

A hard start can occur at random times in combustion engines, even in the John Deere 4020s. Yet, it gets concerning when it starts to happen regularly. This problem blocks the engine from a successful start.


The 1st reason behind this problem is the restriction in the exhaust pipe. If the exhaust pipe is blocked, the smoke cannot be extracted from the tractor. As a result, the diesel hard starts.

The 2nd reason for this issue can be any sort of clogging in the fuel tank. The free movement of the fuel is hindered when this happens.

The 3rd reason is a worn-out fuel filter. It’s a very common reason for other problems in the John Deere 4020 as well. 


The first thing you must do to fix this issue is clean the exhaust pipe. Remove any blockages from it. You may use baking soda and lemon to clean it. 

After that, fix the clogging tank issue by bleeding the tank. You may watch this video for some raw guidelines:

Finally, take out the oil filters of your JD 4020. If they are clogged or too dirty or damaged, replace them.

John Deere 4020 Syncro Range Problems

Problems Reasons Solutions
Shaking shift handle Shift linkage worn-out

Loose cotter pin and bolts

Replace the shift linkages.

Tighten the cotter pin and bolts.

Difficulties in shifting gears Blocked shift linkages

Misadjusted shift mechanism

Worn out synchronizer

Oil shift linkages.

Readjust the shifting rods.

Replace synchronizer.

Problem 1: Shaking Shift Handle

This is a problem where the shift handle keeps shaking when the tractor is on.


The first reason for this problem is the worn-out shift linkages. The second reason for this problem is any loose bolts or cotter pins in the shifting mechanism.


To mitigate this problem, first replace the shift linkages. You can avoid damaged and rusty linkages by doing this.

After that, inspect the area under the shift handle. Tighten every bolt and cotter pin in that area.

Problem 2: Difficulties in Shifting Gears

This is one of the common John Deere 4020 transmission problems as well. Since the synchro and transmission both involve gears, they have the same causes and fixes.


This problem can arise due to blocked shift linkages. They stop the free movements of the gears and pose problems while shifting.

Another reason for this issue can be a misadjusted shift mechanism. Failure to adjust the shift mechanism can directly affect the shifting of the gears.

The last cause of this problem is a worn-out synchronizer. It’s a critical cause as it can make the entire synchro of the JD 4020 dysfunctional.


Start fixing this problem by oiling the linkages. They will free up this way and allow more movement when shifting gears.

After that, readjust the shifting rods of the mechanism itself. You can easily fix the misadjusted shifting mechanism by doing this.

Finally, replace the synchronizer itself if it’s too damaged.

John Deere 4020 transmission problems

John Deere 4020 PTO Problems

Problems Reasons Solutions
PTO slipping Internal oil leak

Lacking freeplay of the main clutch

Fix the leak.

Adjust the PTO clutch.

PTO not engaging Sheared rivets in the clutch disk

Worn-out rings and shaft linkages

Damaged clutch pack

Tighten the rivets. 

Replace the rings and shaft linkages.

Replace clutch pack.

PTO not turning off PTO linkages are worn out

Worn out brake

PTO pressure miscalibrated 

Replace the PTO linkages.

Replace the PTO brake.

Readjust PTO pressure. 

Problem 1: PTO Slipping

In some situations, the PTO of the 4020 JD slips and causes an engine intervention. This can increase the complexity of the tractor control.


Internal oil leakage can make the PTO slippery. Also, lacking freeplay of the main clutch may also cause this problem.


Start off by fixing the internal leak. Check if there’s any bleeding of oil in the PTO section. If there is, fix the leak by replacing the worn/damaged parts. 

Then, adjust the PTO clutch.

Problem 2: PTO Not Engaging

At times, the PTO of the JD 4020 might not engage. There are a couple of reasons for this.


Firstly, the rivets of the clutch disk might be sheared. As a result, the PTO fails to engage.

Secondly, the shaft linkages and rings might be worn-out. At last, the clutch pack might be damaged.


For the fixation, start by tightening the rivets of the clutch disk. Then, check the rings and shaft linkages of the tractor. If they’re damaged, replace them. 

At last, replace the clutch pack of your John Deere 4020. It’ll fix the entire PTO system!

Problem 3: PTO Not Turning off

Sometimes, the PTO of a tractor successfully turns on but stays on and doesn’t turn off. It can be a big problem.


The 1st reason behind this problem is the PTO linkages may be worn out. The 2nd reason behind this problem is a worn-out brake of the PTO.

The 3rd and final reason behind this problem is incorrect PTO pressure. The messed-up pressure factor halts the PTO from shutting down.


First, you need to replace the PTO linkages of the tractor. After that, replace the PTO brake. These two solutions will make sure the PTO is working all right. 

At last, you need to adjust the PTO pressure. Follow the steps below:

  • First, get an Allen wrench. Turn the valve stem with the Allen wrench in the hole through the spool. 
  • Screw stem up into block to increase the pressure. Also, screw it out of the block for less pressure.
    Try not to exceed 300 PSI. It may damage the clutch pack. You can use a hydraulic pressure gauge to get the correct pressure status. 


Why was the John Deere 4020 so popular?

The 4020 John Deere model was popular because it had many special operators and front-end options. Starting from roll-o-Matic, tricycle, and single wheel. Also, it had several customization options. For instance, tire sizes can be matched with the height of different crops to increase efficiency. 

How many bottom plows can a John Deere 4020 pull?

A John Deere 4020 can pull on 5 bottom plows at a decent speed. You may increase the number of bottom plows for this tractor. However, the speed will be affected if you do so.

How much does a John Deere 4020 cost?

The John Deere 4020 costs around 9,500$. This price is based on the average auction sales held in 2017.

The Final Words

That’s everything regarding the john deere 4020 problems. If you got any relevant problems that are mentioned in the article, you can fix them now!

If the problem seems grave and none of the solutions work for you, consult a mechanic. They can fix it for you in exchange for a small fee. 

Best of luck and have a great day.

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