John Deere 4640 Problems (Reasons + Solutions)

John Deere 4640 is a classic tractor and is popular among users. Tractors with close-center, like the John Deere 4640, are less prone to having problems. Still, it can encounter some particular problems.

So, what are the John Deere 4640 problems?

John Deere suffers from fuel gauge not working, and fuel tank cracks issues quite often. The head gasket problem is also a prominent issue. Moreover, transmission issues like grinding while shifting the gears and rear axle issues happen. 

To know the reason, symptom, and solution of each problem, keep reading the whole article.

John Deere 4640 Fuel Issues: Solved

Fuel is known as the blood of a vehicle. This important stuff of your vehicle experiences problems quite often.

Problem Reason Symptom Solution
Fuel gauge isn’t working Faulty sending unit Moving fuel gauge needle Replace the blown fuse and wiring.
Fuel Tank Cracks


Fuel inside the tank is hot Fuel leakage Refilling the tank with repair kit.

Problem 1: Fuel Gauge Not Working

John Deere 4640 Fuel Gauge Not Working
Source: Farmingsimulator22mods

Fuel gauges ensure that John Deere equipment does not suffer unplanned shutdowns. It can be frustrating to have your machinery fail in the middle of your work due to low fuel, which is why you should know how much fuel is left at all times.

So, why can these gauges break and stop working? The reasons can be multiple.


A faulty sending unit is the most common cause of your John Deere fuel gauge not working. John Deere fuel gauges malfunction when the sending unit, float, and variable resistor do not work, causing the signal to shift.

Moreover, A blown fuse and corroded wiring will also interfere with the fuel gauge’s operation. When the wires in the fuel gauge become corroded, they can loosen up and cause the gauge to malfunction.


When the gauge does not work properly, a false low fuel light appears on the dash.  You may also notice moving needles or constant displays of “F” or “E’’.


To fix the issue, you need to follow stepwise guidelines. Let’s get started.

Required Tools: Multimeter.

Step 1: Inspect the Gauge with a Multimeter

When it comes to diagnosing fuel gauge electrical faults, a gauge multimeter comes in handy. In order to determine whether the problem lies with the wiring or the gauge, measure the voltage through it.

Monitoring the current flowing through the gauge will also help identify any electrical problems.

Step 2: Change the Blown Fuse

Fuel gauges that fail due to blown fuses will need to be replaced. Furthermore, you may need to identify the problem that triggered it to fail.

You can easily and affordably fix the problem yourself by replacing the fuse. Remove the old fuse from the fuse box, then replace it with a new one. Fuel gauges should start working again once a new fuse is installed.

Step 3: Replace Corroded Wiring

Ensure that the battery is disconnected before you repair the wiring on your John Deere fuel gauge. You will avoid any potential shocks by doing this. Once the fuel gauge is removed, remove the paneling around it.

Ensure the wiring is free of corrosion once you have access to it. Mild corrosion can be cleaned off with a wire brush. Wires that are severely corroded need to be replaced.

Problem 2: Cracking Fuel Tank

John Deere 4640 Cracking fuel tank
Source: Bigiron

It is unfortunate that this problem has been around for so long. However, this issue may still occur on some tractors.

Hundreds of liters of diesel fuel may leak from a cracked or leaking tank, contaminating your field or farm.


The root cause is driving the vehicle at an extremely hot surrounding temperature. The fuel inside boils if you do it repeatedly.

Moreover, depending on your location, corrosion can worsen your gas tank’s performance. Before the leak gets worse, you must identify its exact source.


The sign is obvious in this situation. You can notice that the fuel leakage happened, and fuel is flowing outside.


Preventing this issue can be as simple as checking your tank regularly and looking for small cracks. However, once it has happened, solving it is necessary.

Required Tools: Protective gear, sandpaper, fuel tank repair kit, degreaser, and hand gloves.

Step 1: Identify and Smooth the Area

First, find out the exact cracking location and use sandpaper to polish the area around it. Now is the time to clean the area with a clean towel. Ensure that all impurities are removed by degreaser.

Step 2: Prepare Repair Kit

Take the repair kit and combine the elements of the two tubes, then apply as soon as possible before the combination hardens.

You will need to cut a piece about 3 centimeters long from the combined material and form a kind of cone with a wide base and a narrow tip.

Step 3: Apply the Combination and Refill the Tank

Using a cone-shaped combination, insert it into the gas tank crack. Once the crack is tightly closed, you can apply the rest of the compound to the smoothed surface.

The process can be simplified with a little water. Then, refill the fuel to see if the intervention worked.

John Deere 4640 Engine Issues: Solved

Engine is the brain of your vehicle. To keep your John Deere 4640 engine problem free, you need to concentrate on this section.

Problem Reason Symptom Solution
Slipping belt Loose belt Drainage of charge Adjust belt tension
Head gasket problems Blown head gasket Leakage on the engine Refilling the leakage with seal

Problem 1: Slipping Belt

When torque demand overrides friction available between a V-belt and one or more shafts, belt slippage happens. As the belt moves with the pulley, it slides back a bit.


The loose belt is the most obvious cause of belt slippage. This causes unwanted heat to be generated. Belt sidewalls become glazed as a result of friction that occurs when a V-belt slips in shafts.


If belt slippage occurs, you’ll notice drainage of charge. Nighttime is the most common time for this to occur.


Considering the belt is in good condition, you need to adjust or tighten the belt tension on your JD. Follow these easy-peasy steps, and you will be good to go.

Required Tool: Wrench

  • Activate parking mode and disconnect the battery cable to avoid electrocution.
  • Pull the top deck to find the belt and an attached spring that is connected to the main body. You will see two screws holding the spring and a bracket.
  • Take a wrench and tighten the screws by rotating them clockwise.
  • Now, pull the bracket back and forth. Check the belt repeatedly while pulling the bracket to ensure it is tight. Adjust the tension with the wrench until the belt moves across the pulley perfectly.
  • Reconnect the power cable to the battery, turn it on, and check if it’s working perfectly.

Problem 2: Head Gasket Leakage

This problem is absolutely familiar to the users of John Deere 4640. The Head gasket is one of the important components of your tractor. So, if anything happens to it, you should investigate the reason as early as possible.


These leaks are usually caused by blown head gaskets. Gaskets have difficulty surviving in a big engine because of high pressure.

The problem is particularly prevalent with tractors that use affordable aftermarket parts for maintenance.


You’ll notice leakage on the engine in the john deere 4640. When you see these leakages, turn off the engine and examine them.


You can simply put a seal into the radiator. To do it, follow the delicate process discussed below.

Required Tools: Hand gloves, steel seal

  • To begin with, you want to have clean coolant in your radiator. If it’s dirty, flush it out and put in new, clean coolant.
  • Then, take the two bolts off the thermostat housing and take the thermostat out. With the thermostat removed, the sealant will flow better and have a better chance of sealing the leak.
  • Now, you just bolt the thermostat housing on without the thermostat inside it. At this point, you need to check the spark plug to see if any of them are burning the coolant. If you find any of them burnt out, take that off.
  • Now pour the seal on the radiator. Now start the engine. Then, you must let the engine idle for about half an hour. And let the sealer do its thing. Do it 4-5 times and give the engine a whole night’s rest. The next morning I put the spark plug in again.

Unfortunately, some head gasket leakage is too big to seal. In this case, you need to pull the head off the engine and replace the head gasket and any other damage that’s done inside.

John Deere 4640 Transmission Problem: Solved

Transmission happens to be the most functional organ of your John Deere 4640. And it gets problems very easily. This part of the article talks about the common transmission issues.

Problem Reason Symptom Solution
Won’t move in reverse Wheel key stock lost Unable to create enough friction Replace a material

Underneath the mower tires

Rear axle problems Rear axle joint corrosion Braking issues while bending Replace axle boot
Grinding when shifting Faulty transmission fluid Friction between the gears Give enough fluid and replace the transmission cable

Problem 1: Won’t Move in Reverse

Sometimes you may face the fact that your John Deere 4640 is not moving in reverse. It’s not unfamiliar to the users of this particular model. It’s one of the serious issues while you’re riding your tractor.


The lawn mower can be stuck in the mud, which happens without friction. Another reason can be the wheel key stock being lost.


The mower cannot move forward or backward because the wheels cannot create sufficient friction with the slippery surface.


To solve this issue, you need to place something underneath the mower tires to restore friction. Even though this solution seems simple, it actually works quite well.

Although sometimes piles of unconnected material will also work, the material must be in ‘sheet’ form. Using another material with potential surface friction can pull tires and even you out of most slippery situations.

Even a large, expensive mower has sometimes been rescued from very loose soil at the bottom of an inclined bank when it became stuck.

Problem 2: Rear Axle Problems

Initially, this problem was common with new tractors, and it still occurs occasionally today. It is possible that the rear axle may need some extra consideration if the tractor is overloaded.

Owners sometimes attempt to prevent these problems by installing the whole axle assembly from another tractor.


Mostly, it happens when axle-joint corrosion occurs. Also, a leaking axle boot can initiate rear axle problems.

It happens you tend to overload your tractor beyond its capacity to carry weight. Also, if you don’t pay much attention to its maintenance, rear axle problems might happen.


As your bent axle wears out, you’ll start having braking issues. The vehicle may skid or slip to a stop as the brake pads shift and get unaligned. Eventually, the brakes will stop functioning altogether.


First of all, you should replace a leaky axle boot as soon as possible. To do so, you need a professional hand. Moreover, to avoid rear axle problems, always ensure you carry weight according to your vehicle’s capacity.

Problem 3: Grinding When Shifting

Transmissions on John Deere, start gritting whenever you shift. This isn’t a huge problem, but it requires repair. You will just be annoyed all the time by this problem.


Poor transmission lubricant, damaged transmission cable, and misaligned binding are the main reasons for having grinding issues.


You may notice friction between the gears if your transmission produces a grinding noise when shifting gears.


To solve the grinding issue, ensure that your transmission receives enough fluid. It is also necessary to change the fluid regularly in order to prevent contamination.

Then, if the transmission cable is worn, replace them as soon as possible. And the binding should be aligned properly to reduce grinding issues.

Prevention of John Deere 4640 Problems

Nothing comes free in life. Likely, you must ensure that you’re taking proper care to prevent unnecessary hassle with your John Deere 4640. Follow the tips given below to avoid unwanted issues.

  • Clean and replace fluid regularly.
  • Make sure to lubricate regularly.
  • The exhaust system, seat, and instruments of your tractor should be protected from rain. Therefore, you should either keep it in a garage or cover it well.
  • Lubricate and check your brake system. You need to get your braking system repaired or replaced as soon as possible if it is not functioning.
  • Air and fuel filters should be checked regularly. You can clean it or replace it if you can’t.
  • You should use the appropriate attachment size for the job at hand. Ensure that your tractor is not overloaded, or it will wear out quickly.


Are John Deere Tractors Reliable?

It is well known that John Deere tractors are some of the most reliable and best on the market. The most reliable tractors are said by some to be these tractors. But even if a brand becomes viewed as reliable by its customers, problems will still arise.

Is John Deere Hydraulics Open or Closed?

The John Deere hydraulics system is open. The open-center hydraulic system is powered by a tandem-gear pump. As a result of this system, the tractor’s hydraulic system receives a high flow rate from two pumps simultaneously.

What is John Deere’s Biggest Engine?

John Deere’s biggest engine is the 18-liter engine, which produces more than 870hp (670kW). The new John Deere Power Systems engine unit features engine controls developed in-house, a common-rail fuel system, and series turbochargers, along with cooled exhaust gas recirculation.


I hope this article on John Deere 4640 problems was helpful enough for you to know about the issues you may face with this tractor.

Tractors made by John Deere are well-known throughout the world. Those green and yellow tractors are a standout in the market.

However, proper maintenance and care can free your vehicle from hassle. You need to ensure that to run the vehicle in the long run.

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