It’s safe to say that any unknown noise coming from a diesel truck can create worry, especially if it’s humming. So why is your vehicle making that sound? We researched and consulted with experts highlighting this concern, and here’s what we found.
A diesel truck may make a humming noise because of underlying causes like:
- Gasket failure
- Vacuum pump leak
- Ruptured exhaust
- Stuck EBPV
- Low power steering fluid
Keep reading as we dive into these possible suspects to your diesel truck’s humming noise in greater detail. We’ll also tackle other relevant yet important topics, such as some potential solutions to remove that noise from your vehicle.
Why Does My Diesel Truck Sound Like It's Humming?
A humming sound coming from within a diesel truck might mean it encountered an issue. Some possible origins of that noise are:
You can typically find gasket seals in a diesel truck’s turbocharger, which is an assembly that extracts power generated from the exhaust to make the compressor function. Those seals help ensure that the turbocharger has wiggle room for it to vibrate while maintaining a secure seal around it.
However, the gaskets may fail or become worn over time. If so, the turbocharger may cause other nearby components to vibrate, resulting in the humming sound.
Vacuum Pump Leak
The vacuum pump is responsible for removing air from the brakes. If it works properly, the pump allows you to step on the brake pedal regularly without encountering problems. But a leak in the vacuum pump may cause the lubricant to escape, which might also be the cause of the humming noise.
Apart from the humming, a leak in the vacuum pump may also lead to other problems like:
- Reduced fuel economy
- Difficulty in stopping the vehicle
- AC fails to cool efficiently
- Oil contamination to different parts of the engine block
A misaligned exhaust pipe may cause it to bump or rub against other parts. This upset might be because of a corroded or loose fastener. The continuous vibrations of the loosened muffler may result in its material cracking or bursting, leading to the humming sound you hear.
Take note that a ruptured exhaust pipe can also lead to serious problems, such as:
- Reduced fuel efficiency
- Poisonous gases may enter the cabin
- Increased heat transference to other parts
Also, failure to solve this concern may result in your diesel truck failing the Ministry of Transport's (MOT) tests. Plus, continuous use of your vehicle while it still has a ruptured exhaust may increase part repair and replacement bills.
Stuck Exhaust Back Pressure Valve (EBPV)
The EBPV should open with the help of oil pressure. That way, it should relieve the stress in the turbo exhaust. But this valve can become stuck in the closed position, preventing the oil from escaping. Your diesel truck may produce a humming sound as its systems try to make the oil pass through the downpipe.
Low Power Steering Fluid
A diesel truck that makes a light buzzing or humming noise might come from a cold start. Bear in mind that power steering fluid lasts about 80,000 to 100,000 miles before you need to refill its reservoir. But you can refill the container as early as 30,000 miles to prevent the system from encountering issues.
How Do You Stop A Diesel Truck From Making A Humming Noise?
First, troubleshoot your diesel truck to find the origin of the humming noise. Then, follow through with the repair process by using the appropriate steps based on your findings.
Don’t forget to pay attention to proper safety protocols. That way, you can prevent accidents and injuries as you fix your vehicle. Some of the preventive measures to take note of are:
- Don’t smoke or keep flammable objects near the workspace.
- Always keep the jobsite as clean and tidy as possible.
- Wear protective gear, such as safety goggles, gloves, and long-sleeved clothing.
- Never put your hand or any part of your body near or on moving automotive parts.
- Ensure that your truck has sturdy supports before going underneath it if needed.
Also, keep in mind that some steps outlined in this section may not work for your specific diesel truck model. So, check your vehicle’s owner’s manual or consult the truck manufacturer if you need additional assistance.
Refill The Power Steering Fluid
The procedure to refill power steering fluid is typically the same across many different vehicles. However, you need to use the correct product to avoid harming your truck's power steering system and engine.
So here are the general steps to complete this task:
What You’ll Need
- Screwdriver or socket wrench
- Drain pan
- Cloth or rag
- Power steering fluid
- Turn off the diesel truck’s engine and let it rest until cold or at room temperature.
- Open the hood and remove the power steering reservoir cap.
- Syphon the leftover power steering fluid with the syringe.
- Refill the power steering fluid container with a new batch to the maximum safest level.
- Close the container and start the engine.
- Turn the steering wheel to the leftmost and rightmost regions a few times.
Check out this product on Amazon.
You can also watch the video below if you need a visual guide for the steps mentioned above:
Reseal The Vacuum Pump
Take note that your new vacuum pump gasket should be compatible with the assembly in your diesel truck. Otherwise, it won’t fit properly, which might also lead to the humming sound becoming louder than before.
With your new gasket ready, continue this process by following these steps:
What You’ll Need
- Socket wrench
- Replacement vacuum pump seal
- Open the hood and locate the vacuum pump, which usually is in the passenger side cylinder head.
- Remove the screws and pull out the top cover of the engine block if needed to gain access to the vacuum pump assembly.
- Use the pick to pull and loosen the insert securing the vacuum pump hose. Remove the hose afterward.
- Remove the bolts securing the vacuum pump assembly and pull them out carefully.
- Remove the worn gasket and install the new one.
- Return the vacuum pump to its original location and secure it.
- Reinstall the cover to the engine block and turn on the truck to check if the humming sound persists.
You might find other problems once you see your diesel truck's vacuum pump. If so, think about replacing the entire assembly instead of only changing the seal.
Check out this replacement vacuum pump assembly on Amazon.
Watch this video to gain additional insights into this procedure:
What Are The Noises Coming From My Diesel Truck?
Aside from humming, a diesel truck may also experience other problems that generate other sounds. Some of these noises to watch out for are:
- Rattling: Usually causes by vibration from filling the gas tank with the wrong type of fuel.
- Knocking: Typically appears when the fuel injectors need a fresh application of lubricant.
- Clicking: May come from the valves because of low oil levels.
Is Diesel Engine Expensive To Maintain?
Diesel engines are usually less expensive to maintain than those powered by gas. Different reasons help in reducing those expenses. For instance, certain diesel engines don’t have parts that you can typically find in gas engines.
Plus, diesel engines often have better fuel economy than their gas-powered counterparts. But it doesn’t mean that diesel motors are better in every aspect. For one thing, gas is typically less expensive than diesel. So, refueling can be more cost-efficient for gas-powered engines than diesel models.
Remember, the humming noise from your diesel truck may come from certain underlying problems. Check different parts of your vehicle, such as the turbocharger’s gasket, vacuum pump, and exhaust pipe. Once you find the source of the sound, use the appropriate solution to eliminate the racket without putting the vehicle in harm’s way.
If you’re looking for answers to other types of noises coming from trucks, check out these other posts:
Clicking Noise When Truck Is Off – What Could Be Wrong?