Mercedes-Benz E420 Hissing noise when brake pedal is depressed Inspection at your home or office.

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Hissing noise when brake pedal is depressed Inspection Service

How much does a Hissing noise when brake pedal is depressed Inspection cost?

On average, the cost for a Mercedes-Benz E420 Hissing noise when brake pedal is depressed Inspection is $95 with $0 for parts and $95 for labor. Prices may vary depending on your location.

CarServiceEstimateShop/Dealer Price
1997 Mercedes-Benz E420V8-4.2LService typeHissing noise when brake pedal is depressed InspectionEstimate$114.99Shop/Dealer Price$132.49 - $145.62
1994 Mercedes-Benz E420V8-4.2LService typeHissing noise when brake pedal is depressed InspectionEstimate$94.99Shop/Dealer Price$112.52 - $125.67
1995 Mercedes-Benz E420V8-4.2LService typeHissing noise when brake pedal is depressed InspectionEstimate$94.99Shop/Dealer Price$112.52 - $125.67
Show example Mercedes-Benz E420 Hissing noise when brake pedal is depressed Inspection prices

Brakes are the most important safety components on your vehicle. Despite that importance, it’s easy to take them for granted, at least until your car begins to do strange things. Ordinarily, pressing your brake pedal should result in only the car slowing down or stopping. If you hear a hissing noise when the brake pedal is depressed, it may mean there’s something that needs to be repaired in the system.

How this system works:

On many cars, the master cylinder works in tandem with a brake booster. The brake booster is mounted to the firewall, generally in front of the steering wheel position, and the master cylinder attaches to it. The entire point of the brake booster is to make it easier to press the brake pedal and slow or stop the car.

Your brake booster works on vacuum pressure. There’s a diaphragm inside that is responsible for maintaining pressure when you’re not pressing the pedal. However, when you do press the pedal, a push rod moves forward within the booster and into the master cylinder. The side of the diaphragm facing the cabin vents to atmospheric pressure, while vacuum is maintained on the other side.

This then equalizes with pressure on the other side of the diaphragm, providing the boost needed to make pressing your brake pedal easier. The hissing noise you hear when the brake pedal is depressed could be nothing more than ordinary operation, or it could be a sign of a deeper problem. There are a couple of different potential issues here, some more severe than others.

Common reasons for this to happen:

  • Leaking Vacuum Line: Your brake booster is supplied with vacuum from the engine via a vacuum hose. It’s usually located near the firewall. If this hose has a leak, it can be heard within the cabin.

  • Leaking Brake Booster Diaphragm: The diaphragm that’s responsible for maintaining pressure within the brake booster can fail, particularly if the master cylinder is leaking fluid into the booster. When this happens, you’ll hear a hissing sound when depressing the brake pedal, but the pedal itself will be much, much harder.

  • Damaged or Missing Foam Silence: Most cars equipped with brake boosters also have a foam silencer that’s designed to help prevent you from hearing that hissing sound. If the silencer has degraded or been damaged, you’ll hear the hissing sound.

  • Failing Master Cylinder: If you hear a hissing sound and suspect that the problem is the diaphragm in the booster, the actual cause is likely the master cylinder beginning to fail. Signs that the master cylinder is leaking into the brake booster include low fluid in the reservoir with no visible leaks.

What to expect:

A top-rated mobile mechanic will come to your home or office to inspect your brake system, including the brake pedal operation, the brake booster and listen to the hissing sound. The mechanic will then provide a detailed inspection report that includes the scope and cost of the necessary repairs.

How it's done:

The mechanic will need to crank the car in order to verify the hissing sound, and a test drive may be necessary to duplicate the complaint. Additionally, the mechanic will inspect the brake pedal operation, the condition of the brake booster, the master cylinder, the level of fluid in your system and more.

How important is this service?

Power brakes are wonderful things, making it far easier to work a brake pedal that would otherwise require significant force to activate. While the hissing sound may be a sign of nothing more dangerous than a failed piece of foam, it could be a symptom of something much more worrisome – a damaged brake booster and a failing master cylinder. You cannot afford to take chances with your brake system. One of our professional mechanics can inspect the entire system and determine if there’s cause for concern, and what needs to be done if there is a problem.

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Excellent Rating

(24)

Rating Summary
18
2
1
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2
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Nicholas

11 years of experience
585 reviews
Nicholas
11 years of experience
Mercedes-Benz E420 V8-4.2L - Thermostat Housing - Raleigh, North Carolina
Great.

Jesus

16 years of experience
68 reviews
Jesus
16 years of experience
Mercedes-Benz E420 V8-4.2L - Pre-purchase Car Inspection - Long Beach, California
I requested a pre purchase inspection for a car about 200 miles away from where I live. Jesus was on time, responsive, and very pleasant to work with. He kept me abreast of his inspection and provided me his professional feedback on the status of the vehicle. He followed up with a comprehensive and easy to understand report of his findings. Awsome service and awesome professional mechanic. Thank you.

Andrew

11 years of experience
337 reviews
Andrew
11 years of experience
Mercedes-Benz E420 V8-4.2L - Engine is running louder than normal Inspection - Glen Burnie, Maryland
Andrew was on time and knowledgeable. He was honest to determine no work was necessary. He took the time to research another mechanic issue and gave a quote.

Brian

22 years of experience
132 reviews
Brian
22 years of experience
Mercedes-Benz E420 V8-4.2L - Oil Change - Springfield, Virginia
It's the second time Brian has worked on my car (I should've left a comment the first time, but forgot). Each time he not only has been efficient, he's been a real professional. We also have a good time while he works. He's worked on my car at home and at my office and no matter where he works, I've been very satisfied. Owning an older model Mercedes Benz, I always worry that others won't treat it the way I feel it should be treated, but Brian does. He's knowledgeable and gentle with every part he handles and every screw or bolt he turns--I appreciate that. If my first two experiences are any indication of the future, my car is in good hands. Thanks Brian.

Excellent Rating

(24)

Rating Summary
18
2
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18
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Number of Mercedes-Benz E420 services completed
264+
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