John Deere 4520 Problems (Reasons And Solutions)

John Deere 4520 is one of the most popular models of JD Tractors. Although the owners are satisfied with its service, some problems every now and then are inevitable. 

The engine not starting and engine cranking and knocking sounds are the most common John Deere 4520 problems. Sometimes the PTO may not work or steering may not have normal opposition.

Refilling the oil tanks and changing the fuel and air filter regularly solve most problems. Check all the wiring connections and keep all the engine components clean to fix common problems. 

In this article, you will find all the common problems that your tractor might show with their reasons, and proper solutions. So, keep scrolling. 

John Deere 4520 Engine Problems

Problems Reasons Solutions
Engine Won’t Crank  Dead battery

Using the wrong fuel

Broken injection pump

Off-timing of fuel injection

Recharge the battery.

Use the right fuel.

Replace the injection pump.

Adjust the fuel injection timing.

Difficult To Start The Engine Stuck fuel lines

Clogged fuel filters

Clogged exhaust pipes 

Dirty fuel injectors

Closed fuel shut-off valves

Clean the fuel line.

Replace the fuel filter.

Clean the exhaust pipes.

Clean the fuel injector.

Open the fuel shut-off valves.

Engine Knocks  Lack of engine oil 

Lack of coolant

Incorrect fuel injection timing

Worn-out crankshaft bearing 

Loose flywheel screws

Refill the engine oil.

Refill the coolant.

Adjust the fuel injector timing.

Replace the crankshaft bearing.

Tighten the flywheel screws.

Engine Regularly Overheats Lack of coolant

Dirty or clogged radiator 

Defective fan belt

Overload engine

Refill the coolant.

Clean the radiator.

Replace the fan belt.

Don’t drive the tractor at high speed for long.

White Smoke Emission Broken piston rings

Clogged air filters

Replace the piston rings.

Replace the fuel filter to solve the John Deere 4520 Problems.

Problem 1: Engine Won’t Crank

John Deere 4520 owners often complain that their tractor’s engine doesn’t crack. 


There can be a number of reasons behind this problem. For example, a dead battery, using the wrong fuel, a broken injection pump, and off-timing of fuel injection. 


You have to troubleshoot each reason in an elimination method.

  • Check and recharge the battery.
  • Make sure to use the right type of fuel. John Deere manufacturers recommend using ultra-low sulfur diesel (ULSD) fuel in their tractors.
  • Check the fuel injector for visible damage. Locate the fuel rail near the engine. Remove the rail’s volt using a compatible socket and ratchet. Take the rail out and check if the fuel pump is worn out. The worn-out fuel injection pump needs to be replaced. 
  • Check the fuel injection timing and if the timing is off, you need to adjust the fuel injection timing

Problem 2: Difficult to Start the Engine

It’s a very common problem that sometimes the John Deere 4520 is very difficult to start. Although worrisome, it might be happening for some simple reasons. 


Stuck fuel lines, clogged fuel filters, and clogged exhaust pipes are the most common reasons for a tractor engine to not start. Dirty fuel injectors and closed fuel shut-off valves can be the reason behind this problem as well. 


  • First, check if the fuel shut-off valve is closed or open. If it is closed, open it. 
  • Remove the fuel injector rail and take out the fuel injector. If there is any dirt on it, take a washcloth and clean them off. 

After that, you have to check the fuel line. 

  • Turn off the fuel line plug and remove the fuel line by removing the clamps. 
  • If the line is broken or worn out, replace it. 
  • If there is any clog in the line, soak it in water for some time and stick a thin wire inside it to remove the clog. Then reinstall the fuel line. 

If the fuel filter is clogged, replace it.  Here’s how to replace the fuel filter in John Deere 4520. 

  • Shut off the fuel supply and relieve any pressure in the fuel system by turning the fuel shut-off valve to the “off” position and starting the engine until it runs out of fuel.
  • Locate the fuel filter in John Deere 4520. It is near the fuel tank along with the fuel line. 
  • Take a wrench and loosen the filter. 
  • After loosening the fuel filter, take it out from the fuel line.
  • Properly place the new fuel filter. Make sure it is correctly seated and tightened. 
  • Turn the fuel shut-off valve to the “on” position and start the engine to ensure that the fuel filter is working properly.

Now, you have to open and check the exhaust pipe. Here’s what to do:

  • The exhaust pipe is secured to the muffler with clamps. Use a wrench to remove those clamps. 
  • Inspect the exhaust pipe for any debris or dirt. 
  • Clean the exhaust pipe with a wired brush. 
  • After cleaning the exhaust pipe, reattach it to the muffler. And re-plug those clamps. 

Problem 3: Engine knocks

If there is any unusual knocking noise coming from the engine, you need to identify its source and fix it immediately. A knocking sound is an indication of an engine problem. 


Lack of enough engine oil or coolant, incorrect fuel injection timing, worn-out crankshaft bearing, and loose flywheel screws cause the knocking noise. 


Check the engine oil level and if it is low, refill the oil. Follow the steps to refill the engine oil:

  • From the side of the engine locate the oil filter and from underneath the tractor, locate the drain plug. 
  • Place an oil drain pan underneath the oil drain plug and remove the drain plug with an adjustable wrench. Let the older oil drain out and reinstall the drain plug after that. 
  • Remove the dipstick from the oil tank and place a funnel on the tank opening. 
  • Carefully add engine oil to the tank. 
  • The engine oil capacity for John Deere 4520 is 14 Qts. Keep checking the oil level using the oil dipstick. And make sure not to overfill the tank. 
  • Replug the fuel tank dipstick. 

If the engine oil is full, check the following factors: 

  • Check the coolant and refill if necessary. John Deere 4520 has 28 Qts of coolant capacity. Don’t overfill the coolant tank. 
  • Inspect the fuel injection timing and if found incorrect, adjust it. The following video might help you with that. 
  • Remove the timing cover and check if the crankshaft bearing is damaged or worn out. If the bearing is damaged, you need to replace it. As the process is complicated, consult a technician to fix it. 
  • Check if the flywheel screws are properly adjusted. If not, take an adjustable wrench and tighten it correctly. 

Problem 4: Engine Regularly Overheats 

The normal temperature for a tractor engine is around 180 degrees Fahrenheit while operating. If your tractor’s engine gets excessively hotter than that, it is an indication of an engine problem. 


The engine overheats due to lack of coolant, dirty or clogged radiator, defective fan belt, and overload engine.


  • If you often overload the engine by driving the tractor at a high speed for a long time, you should avoid that. Also, don’t carry excessive weight on your tractor. 
  • Check the coolant level and refill it if necessary. 
  • Inspect the radiator, if it’s dirty, you need to clean it. Use a hose to flush out the inside of the radiator. If the radiator is extremely dirty, you can use a radiator cleaner to properly clean the radiator. 
  • Inspect the fan belt. If the belt is torn or worn out, you have to replace the belt immediately. 

Problem 5: White Smoke Emission

White smoke emission from the tractor exhaust pipe is not only harmful to the environment but also harmful to the engine. 


Broken piston rings and clogged air filters are the main reasons for the excessive white emission. 


Inspect the piston rings by removing the cylinder head. If the rings are found broken or worn out, replace those. 

You need to inspect the air filter as well. If found dirty or clogged, replace the air filter. 

  • Locate the air filter housing near the top side of the engine. Remove the housing lid. Once the cover or lid is removed, you should be able to see the filter element inside the housing.
  • The air filter is held in place by clips. Remove those clips and carefully remove the old filter element from the housing
  • Now, install the new filter element. Make sure it is seated properly in the housing and the clips are installed correctly.
  • Replace the cover or lid on the air filter housing and close it securely.

John Deere 4520 Transmission Problems

Problems Reasons Solutions
Front Axle Rumbling Noise Faulty front axle bearings 

Loose wheel hubs

Faulty drive belts

Replace the bearings.

Tighten the wheel hubs.

Replace the drive belts.

No oil coming from transmission Lack of transmission oil

Clogged oil filter

Worn-out transmission seals

Refill the transmission oil.

Replace the oil filter.

Replace the transmission seals to solve the John Deere 4520 Transmission Problems.

Problem 1: Front Axle Makes Constant Rumbling Noise

A common John Deere 4520 transmission is constant rumbling noise from the front axle. 


Faulty front axle bearings, loose wheel hubs, and faulty drive belts are the reasons behind this noise from the front axle. 


First, check if the wheel lug nuts are loosened and tighten them if necessary. 

If the lug nuts are properly tightened, the problem can be with the axle bearing. To check and replace faulty bearings, perform the following steps:

  • Lift the tractor with a jack and secure it properly. 
  • Loosen the lug nuts and remove the front wheel from the hubs. 
  • The bearings are covered by the hubs, so you have to remove them as well.
  • The hubs are protected by bolts. Take an adjustable wrench and remove those bolts. Take out the hub carefully. 
  • Now, you should be able to access the axle bearings. Carefully remove the old bearings and inspect them for signs of wear or damage. If the bearings are worn or damaged, you have to replace them.
  • After installing the new bearing, reassemble everything. 

Problem 3: No Oil Coming From the Transmission 

You may sometimes face no oil coming from transmission problems or incorrect oil pressure in your John Deere 4520. 


Lack of transmission oil, clogged oil filter, and worn-out transmission seals are responsible for this problem. 


  • Check the transmission oil level and refill the transmission oil tank if necessary. The recommended oil type for John Deere 4520 tractor’s transmission is John Deere 303. And the transmission oil capacity for this tractor is 72 Qts. Don’t add more oil than that. 
  • While changing the oil level, inspect the oil filter as well. If the filter is clogged, you need to replace it. 
  • If these don’t work, the transmission sealants must be damaged and you need to replace them at a mechanic shop. 

John Deere 4520 PTO Problems

Problems Reasons Solutions
PTO Not Working Turned-off PTO switch

Broken hydraulic solenoid

Broken or clogged hydraulic piston

Turn on the PTO switch.

Replace the hydraulic solenoid.

Replace the hydraulic piston.

PTO Is Stalling Bad PTO clutch or valve Repair or replace the clutch or valve.

Problem 1: PTO Not Working

Some John Deere owners complain about the PTO not working. Sometimes, the PTO engages but then the engine shuts down. 


A broken hydraulic solenoid, a broken or clogged hydraulic piston, and a turned-off PTO switch can be the reasons behind this PTO problem.


  • First make sure the PTO switch is turned on. 
  • You need to check the Hydraulic solenoid and hydraulic piston for any tear or wear. Accessing these parts is complicated. You have to remove the seat, SCV block, hydraulic block, and hydraulic valves to reach them. So, if you don’t have prior mechanic experience, it is recommended to have it fixed by a mechanic. 

Problem 2: PTO Is Stalling

In this situation, the PTO will engage and turn, but after some time it will start stalling. 


Your John Deere 4520 tractor’s PTO might be stalling due to a bad PTO clutch or valve. 


You need to identify any visible damage like wear and tear in the PTO clutch and PTO valve. And you have to replace these components if found damaged. These are complex processes. 

You can follow the video below to have a clear idea. 

Or, you can just take the tractor to a mechanic shop. 

John Deere 4520 Steering Problems

Problems Reasons Solutions
The Steering Wheel Turns Easily Lack of oil in the tank 

Damaged steering cylinder 

Faulty steering pump

Refill the oil tank.

Repair the steering cylinder parts.

Replace the steering pump.

Steering Wheel Works Tight Lack of hydraulic oil

Leaking hydraulic connection

Defective power steering pump

Defective power steering

Refill the hydraulic oil.

Replace the faulty cable or seals.

Repair or replace the steering pump.

Replace the power steering to solve the John Deere 4520 Steering Problems.

Problem 1: The Steering Wheel Turns Easily 

In this situation, you won’t find the usual opposition while turning the steering wheel. 


Lack of oil in the tank, damaged steering cylinder and faulty steering pump can be the reason behind this problem. 


  • Refill the steering oil tank to an adequate level. 
  • Inspect the steering cylinder for any visible damage. Also, inspect the cylinder mounting brackets and hose connection. If you find any of these parts to be damaged, you need to repair or replace them with the help of a technician.
  • Locate the steering from near the power steering reservoir. Inspect for any tear or wear of the pump, seals, and bolts. If any part is found damaged, repair or replace those. 

Problem 2: Steering Wheel Works Tight

Another common steering problem is the steering wheel is too tight. 


Lack of hydraulic oil, leaking hydraulic connection, defective power steering pump, or defective power steering can be the reason for too much opposition in the steering wheel. 


  • Check the hydraulic oil tank and refill the tank. 
  • Check the hydraulic connections for leaks. If you find any leaks on the connecting cable or the seals, these parts are damaged and you need to replace those. 
  • You have to inspect the power steering pump and if any part is found defective, repair or replace those parts. 
  • Finally if nothing of the above works, the power steering needs to be thoroughly checked and if the steering is faulty, it needs to be replaced.

Now, you should get the proper opposition in the steering wheel. 

John Deere 4520 Other Problems

Problem Reason Solution
Motor Won’t start Dirty or clogged fuel system

Incorrect fuel pump timing adjustment

Bad starter

Dirty fuel or air filter 

Worn-out piston rings

Clean the fuel system.

Adjust the fuel pump timing.

Repair or replace the starter.

Replace the fuel and air filter.

Replace the piston rings.

Fuel gauge not working Blown fuse

Corroded wiring

Defective sending unit

Defective fuel gauge

Replace the fuse.

Replace the wiring.

Repair or replace the sender unit.

Replace the fuel gauge.

Problem 1: Motor Won’t start 

John Deere 4520 motors can sometimes stop working altogether and sometimes it can be hard to start. 


There are several reasons behind this motor problem. For example, dirty or clogged fuel system, incorrect fuel pump timing adjustment, bad starter,  dirty fuel or air filter, and worn out piston rings.


  • First, inspect and replace the air and fuel filter if required. 
  • Check the fuel system including the fuel tank and fuel line. To clean the fuel line, blow air toward the fuel tank with an air compression nozzle. After that, clean the fuel tank with a cleaning solution. Refill new fuel. 
  • Check and adjust fuel pump timing. 
  • Identify the symptoms of a bad starter and repair them as needed. Most likely you need to change the starter solenoid. 
  • Finally, you need to check the piston rings by removing the cylinder head and engine blocks. If the rings are worn out, replace them. 

Problem 4: Fuel Gauge Not Working 

If your tractor’s fuel gauge doesn’t work, your tractor will often face unexpected shutdown due to insufficient fuel. In John Deere 4520, a broken fuel gauge is a common problem. 


Blown fuse, corroded wiring, a defective sending unit, or a defective fuel gauge is the reason behind this problem.


  • Check the fuse for the fuel gauge. If the fuse is not securely in the socket, fix it. And if the fuse is blown, replace it. 
  • Remove the fuel sender and measure the pressure with a fuel pressure gauge. you will find the recommended fuel pressure in the owner’s manual of your John Deere 4520 tractor. If the pressure doesn’t match, replace the fuel sender. 
  • Check the wiring that connects the fuel gauge to the rest of the tractor’s electrical system. If the connection is loose, fix them. And if the cables are torn or worn out, you need to replace those cables. 
  • If none of the above is a problem, then the fuel gauge itself is faulty and requires a replacement.


These are all the common John Deere 4520 problems. You can fix most of these problems by yourself.

Regular maintenance of the tractor will help you avoid these problems and keep your tractor in a good condition for a long time. 

That’s it for now. Have a great day!

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