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Volvo Truck Gearbox & Transmission Problems: Faults & Fixes!

The gearbox and the transmission can last for the entire lifetime of your Volvo truck. However, they will still need regular repair.

A faulty gearbox and transmission can cause difficulty as you drive your Volvo truck.

You may notice how it will shift gears randomly as you are driving. Just imagine how dangerous driving on a slope or a muddy road will be.

The gearbox and the transmission are almost similar. After all, the gearbox is part of the vehicle’s transmission. Thus, these components may experience the same problems as well.

In this article, we discuss common Volvo truck gearbox and transmission problems.

A Short Summary of Common Volvo Truck Gearbox Problems to Expect:

A Volvo truck’s most common gearbox problems are lack of acceleration, insufficient throttle response, fluid leakage, grinding noise during gear shifts, slipping gears, and burning smell. These critical gearbox issues must be fixed asap to prevent further gearbox damage and safe driving.

A Short Summary of Common Volvo Truck Transmission Problems to Expect:

A Volvo truck’s common transmission problems are random gear shifts, leaking fluid, burning smell, difficult gear shifting, grinding or shaking of the standard transmission, clunking or buzzing noises, low air supply, and air leak. Transmission issues may also be a result of a worn-out gearbox.

Volvo FH12 Gearbox Problems

Even the Volvo FH12, awarded as the “Truck of the Year” in 1994, encounters gearbox problems.

Some truckers encounter gear jumping on their FH12 gearbox. 

The easiest solution for this issue is to pull the inhibitor relay. If your truck is already old, it may often get stuck.

Another problem frequently occurring in Volvo FH12 is that it will not move or reverse in gear. It will only move in limp mode and switch to neutral.

The primary fix for this problem is an oil change and cleaning all electronic connectors to the transmission and clutch plate.

If there are no changes after these quick repairs, the best thing to do is take your truck to a Volvo dealer or any transmission shop.

They will complete a diagnostic using the OBD-II scanner to see the possible problem. They can also conduct the necessary repairs to prevent your truck from further damage.

Volvo Truck Gear Problems

There are several gear problems you can encounter with your Volvo truck. Here are some of them and their diagnosis.

  • Lack of acceleration

There is a slight delay in the acceleration after shifting gear. However, this is a regular occurrence if you are in manual transmissions. 

But on automatic, it is an attention-worthy issue. What you can do is engage and disengage the clutch.

If the problem persists, the issue is on the air system. It can be fixed by simple bleeding or replacing the parts affected.

  • Fluid leakage

The gearbox needs fluid for lubrication. If you see any liquid drops in a bright orange color accumulating on your truck’s gearbox, the transmission fluid is probably leaking out.

If you detect the leak early, you can change the fluid pan. 

If it is already an undetected issue for quite some time, there are possible damages incurred on the gearbox components. Thus, repair and replacement are a must, which may cause you a hefty amount.

  • Grinding noise during gear shifts

A problem with the gears can also cause grinding noises during gear shifts. Sometimes, you may also notice visible shaking of your truck.

Most of the time, the reason for the noises as you shift gear is on the clutch pedal. But if the noise occurs after you take your foot off the pedal, the problem lies with the gear synchronizers.

Either way, parts replacement is the key to getting rid of the grinding and further damaging of your gearbox.

  • Slipping gears

Gear slipping is when you shift gear and step on the accelerator, and the truck jerks and goes back to the previous gear. There are instances when gear also goes into neutral.

When this happens, your truck already has a damaged shift fork. It can put you in dangerous driving situations, so you must pay attention immediately.

  • Burning smell

A burning smell coming from the gearbox is an indication of improper gear shifts. It occurs when the transmission fluid overheats and causes friction to the gearbox components.

If you use the wrong fluid, this problem may occur. You must use the correct fluid and top it up on time to avoid frequent overheating.

Volvo Truck Geartronic Problems

Geartronic is the manumatic automatic transmission of Volvo trucks.

There are two most common problems you will encounter with this one. First is the faulty gearbox, and the other is the faulty warning lights.

You will notice on the gearbox that sometimes the upshifts are late, and the engine revs get high during the acceleration.

While standing in traffic, the gear will jump first while your foot is on the brake and then move against your will.

It can also affect the warning lights and show you that transmission service is required.

The thing is, these problems often come and go. But if it already happens more frequently, you need to know how to fix it to avoid accidents on the road.

You can check with the dealer if the transmission is already on its latest software. Replacing the valve body will also be necessary.

Volvo Truck I-Shift Problems

The I-Shift is the automated manual transmission of the Volvo trucks.

When driving a truck with the I-Shift transmission, you can also encounter weird actions on its gears.

For example, the truck will start to jerk when backing up on an uphill on low reverse.

When someone pushes the truck from the outside, and as you release the clutch pedal on a manual switch, it goes back to normal.

When encountering this problem, the best thing to do is to check for possible oil and air leaks first. These two issues happen with no warning signs, so you can still drive the usual.

However, if it happens more often, your mechanic will likely advise that your truck needs a new I-Shift transmission. If it is not too severe, a clutch replacement can solve it.

Volvo Truck Clutch Problems

Clutch problems are indicators that something is going wrong in your Volvo truck. The key is to recognize this problem before severe damage to the transmission and gears.

The clutch system must be free of air for proper and efficient operation. It means it has to be bled as soon as the pedal action becomes soft and spongy.

You can do it by topping the fluid level in the clutch master cylinder reservoir until it is complete. It would be best if you had assistance from another person to pump the clutch gently and hold it down.

Then, loosen the bleeder screw above the slave cylinder assembly to release the trapped air. After that, close the bleeder screw and repeat the process until the air is completely evacuated from the system, and the clutch works perfectly fine again.

Volvo Truck Automatic Transmission Problems

Some common automatic transmission problems of a Volvo truck are the B4 servo, valve body, transmission fluid, transmission overdrive relay, and delayed shifting when the transmission gets hot.

You can conduct troubleshooting to prevent further damage to the transmission. You can follow these steps:

  1. Check the transmission fluid level.
  2. Read the transmission fault codes.
  3. Update the TCM software.
  4. Inform your dealer to install the update free of charge, especially if the truck is under warranty.
  5. Change the transmission fluid and filter.

Volvo Truck Transmission Low Air Supply

It is easy to detect a low air supply on your Volvo truck transmission because of the loud air leak sound it produces.

You will already have a warning signal of transmission system failure because of low air supply.

The main reason for low air supply is air leakage. If you prevent the air from going out, you can maintain the ideal air supply in the transmission.

Volvo Truck Transmission Air Leak

You must look for the leak to fix air leak problems with your Volvo truck’s transmission.

You can do it by setting both breaks and filling the air tanks. Then, release the breaks. Observe if it is already dumping air. If yes, you can quickly locate the area where the air leakage occurs.

You can also try spraying liquid on the suspected areas of air leaks. If you notice any bubbles, that is where you need to fix them to prevent more air from coming out.

If you are unfamiliar with this issue, you can always take your truck to your trusted repairman to do the job.