How To Find Air Leak on Semi-Truck?

Several parts of semi-trucks need hydraulic pressure for their functioning, including brake components, vacuum hoses, and steering parts.

How To Find Air Leak on Semi-Truck? You can find air leaks on semi-trucks with soapy water spray, chalk dust test, visual and audible inspection, smoke machine, and pressure gauge use, use old stethoscope, UV dye, and ultrasonic acoustic detectors. Moreover, you can fix the air leaks by replacing the whole assembly, tightening the connections, and repairing the damaged parts.

This leakage usually happens in different components of trucks because of their loose connection. The issue comes when connectors used to connect two parts become loose. In addition, damaged gaskets, seals, and punctured tubes provide an escape route to air.

How do you find air leaks on a semi-truck?

Inspecting the air leaks in your semi-trucks as part of their proper maintenance schedule is necessary. In addition, I also check it weekly to ensure the functioning of the respective parts. You can use simple methods to identify these instead of taking your vehicles to the dealerships.

Soapy water spray

You can make a mixture of soapy water in a plastic bottle to check air leakage in your vehicle. However, soapy water is not a reliable detection tool because some areas are hard to reach and remain undetected.

In addition, soapy water can also lead to corrosion on metal material if you do not wipe it off after completing the inspection procedure.

Handful application of soapy water spray is essential because electric wires are near the air intake systems. Add water in a plastic bottle and put a few drops of handwashing detergent or dishwasher.

Mix it well and then spray the mixture near the fittings and pipes of the systems. The formation of bubbles near connections and pipes represents wear and tear. Wipe off the soapy water from their surfaces with a clean cloth.

Chalk dust test

My friend is an expert semi-truck driver, and he told me that he found air leaks in the braking system because of wear and tear in their components.

He identified the problem because of the decreased efficiency of the braking system. He told me about the chalk dust test, which is easy to perform and takes less time.

It is not a precise method when standing in highly windy areas. Mix chalk dust with water on several parts and run the systems.

Use the brush for chalk dust application and apply a single coat. Pressure the system, and the chalk dust coat blows away from the vulnerable area because of air pressure.

Visual and audible inspection

You can use visible and audible inspection techniques to find air leaks in different parts of semi-trucks. You should check the fittings and connections of the braking system, vacuum hoses, and steering parts.

Inspect for the loose connections and tighten these to resolve the problem. You can typically use visual inspection techniques to check leakage in diesel engines.

Check the connections of the pump and tank. Moreover, you can also use audible techniques to track the damaged parts.

You can hear the hissing and squealing sound, usually produced because of air movement from the leaked pipes and poorly connected hoses.

Smoke machine

Many people use smoke machines to identify the leakage in engine components. You have to connect these smoke machines with any of the vacuum hoses.

Turn off the engine and connect the smoke machine with a vacuum hose. Turn on the engine and smoke machine to send white-colored smoke to several parts.

You can see white smoke buildup in affected parts because white smoke comes outside from the damaged parts. You should carefully use the smoke machine and regulate the smoke because it can damage the engine parts.

I do not use smoke machines for air leakage detection because it requires knowledge and experience for smoke adjustment.

Use of pressure gauge

Several components of semi-trucks require optimal pressure range for their correct functioning. The optimal pressure of the braking system should be between 100 to 120 psi for their correct functioning.

The system is designed to apply brakes at a specific pressure range. Pressure less than 100 psi shows air leakage in the systems.

You can identify the issue by monitoring the pressure through a gauge. I always check the air braking system pressure after 2 to 3 days to ensure optimal functioning and reduce the risk of damage from loose or damaged connections.

Check corrosion

Air system connections, including fasteners and pipes, are usually made up of metal. Metal-based construction makes their parts more vulnerable to corrosion attack.

You can see dark brown cracks on metal parts because of oxidation reactions that ruin the metal material. Corrosion inspection is a clear sign of air leakage in trucks.

Corrosion-related holes and cracks provide the escape route to air and decrease the overall pressure of the system, which eventually disturbs its normal functioning.

An old stethoscope or rubber piece

You can use the old stethoscope to hear the hissing and squealing sounds that are the most common symptoms of air leaks in semi-trucks.

Using a stethoscope is the best choice because it reflects the low-frequency sounds you cannot usually hear with your ears.

These contain diaphragms that vibrate because of sound production. Vibrated sound travels through the hollow tubes and to the earpieces.

I was traveling with my doctor friend, and he had a stethoscope. I heard the hissing sound when I parked my truck, but I could not find the exact origin.

I was sitting near the undercarriage to figure out the origin of the sound, but it was unclear. My friend gave me a stethoscope to hear the sound from different parts.

I used this device, which was coming from the vacuum hoses because of air leakage. You can use the rubber hose to increase the audible frequency instead of using a stethoscope.

UV dye

Many people prefer to add UV dyes of different colors to identify the damaged parts of the air system in their semi-trucks. The use of UV dye is not reliable because it can contaminate the motor oil and brake fluid.

Add the UV dyes to the hoses and pressurize the system. Dripping of UV dyes from different parts depicts loose connections or damaged pipes.

You have to replace the engine oil after performing the UV dye method.

Ultrasonic acoustic detectors

It usually produces low-frequency hissing and squealing sounds. Sometimes, these are not audible because of wind and traffic noise.

You can use devices that have a more audible frequency range. These devices can catch low-frequency sounds that are not audible to human ears.

Use these devices so they can catch the low-frequency hissing sound and make you aware of the challenging situation.

How do you fix air leaks on semi-trucks?

It is necessary to fix the air leakage in semi-trucks because braking components, vacuum hoses, and steering parts lose their working efficiency.

Use the wrench to tighten the loose fitting and connections. Sometimes, the issue comes from damaged fasteners, and you should replace the damaged ones with new brass connectors.

Replace the cracked or punctured pipes with new ones of the same sizes and material. Replace the rubber seals or O-rings that are located on air compressors because these can harden and crack over time.

Things to consider

You have to consider several things when you are doing the audible inspection. Squealing and hissing sounds are of low frequency, and noise from the surroundings causes an interruption in their identification.

Surrounding noises can also cause misinterpretation, which can lead to costly repairs. Parking your vehicle at the leveled and safe parking areas is better.

Park your trucks away from the traffic area to reduce the noise and distractions. I also turn off the music while inspecting so it cannot affect the audible frequencies.

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