By June 18, 2012 Read More →

Hissing Noise Under Dash

I have a Chevy Blazer with a 4.3L. It all of a sudden started stalling out at idle or when I’m at a stop light. I also hear like a hissing noise when I push the brake.

This noise is coming from under the dash inside the truck. I believe this is making the truck idle rough and stall out. As each day goes by its getting worse. Any information will be greatly appreciated.

Thanks Rollie

Hi there Rollie,

It sounds like you have a bad vacuum brake power booster, or the check valve or hose going to the booster has a hole in it causing a vacuum leak. Make sure the rubber vacuum hose is plugged into the brake booster and there are no leaks in the hose.

They usually offer a rebuilt brake booster without the master cylinder, so you can just remove and replace the booster without having to re-bleed the brake lines.

You can also buy a booster from a junk yard, but I would use YOUR existing master cylinder not the one that has been sitting up in the junk yard for years..

Here is a picture of what the items I mentioned look like under the hood

Austin Davis

About the Author:

Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."

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