When I apply the brakes on my 1995 S-10 I can hear the vacuum running from the engine to the power brake booster. It pulls vacuum as long as I have my foot on the brake.it is quite loud The vacuum diaphragm seems to be ok. is this normal. also if I make a quick stop the brake pedal will drop about 1 inch after I apply maximum pressure is this something that the ABS is doing. I thought of replacing the booster as my brakes take a lot of pressure to apply, but I have never known of a booster going bad if the diaphragm is good. Any one have any suggestions
S-10 Brakes Hiss
May 28, 2004
3 Replies
A good diagnostic test to try:
Shut the engine, pump the brake pedal five or six times to make absolutely sure, that there is no residual vacum in the booster.
Press the pedal lightly, then start the engine. If the pedal goes down fast with no pressure required(That's why I said to press the pedal lightly). Then the booster is fine.
If you need to apply a little more pressure than you are accustomed to, the diaphragm is bad, and that's why it hisses constantly when you have the pedal depressed.
Refinish King
If you hear a hissing noise when you push the brake pedal down, (vacuum leak at the booster) replace the brake booster. It doesn't matter if you still have good assist, it's defective.
Ian
Like Ian said, he needs a new booster regardless of the outcome of your test. If it's leaking vacuum (and it is) the only fix is a new booster. Bob
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