Leaking brake booster [Archive] - GrandAmGT.com Forum


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06-24-2012, 02:49 AM
heard the leak started gently pushing and pulling hoses. hose from uim to master cylinder from uim where it connects to master cylinder. Cause?Consequences?Cost for DIY?

06-24-2012, 06:01 PM
yeah i know no one wants to reply because this tiny job is self explainable. Any little bit of info of any difficulty of job is always great.

06-24-2012, 08:39 PM
First off, there is no hose going from the UIM to the master cylinder. It goes the brake booster, which is behind the master cylinder.

Second, you didn't provide enough information. Which end is it leaking from? The side connected to the UIM, or the booster end? Does it do it only when the engine is running, or when the engine is off? Does it only do it when you move it, or all the time?

We can't tell you whats wrong or how to fix it if you don't even know what you are trying to tell us. ;)

06-25-2012, 09:53 AM
Leaking from brake booster side. Does it while it's running and you can hear the rest coming out right after when you turn it off. Does it while it runs all the time. You can hear it stop when it's running and you push in on it.

06-25-2012, 06:05 PM
Ok, there is a rubber grommet in the case of the brake booster with a check valve inserted in it. That is what the hose coming from the UIM is connected to... the check valve. It's supposed to hold vacuum in the booster so when you are going WOT and there is no vacuum in the manifold, you will still have power brakes.

If it's leaking from there, then basically something isn't tight. Either the check valve isn't closing all the way anymore, or the rubber has gotten old and stiff and doesn't fit tight anymore. It's hard to say what exactly without seeing it. You might have to replace all three... the grommet, the check valve, and the vacuum supply hose. Shouldn't cost much, and that would be the easiest way to know there aren't any more problems.

06-26-2012, 11:51 AM
Thanks AaronGtr. the rubber is probably getting old. The close to 100 degree summers and then down to 15 degree cold winters is making a bunch of smaller problems like different small rubber units. As long as using it like that won't cause major damage than everything is fine and it will hold over until i can pay to replace it. My car really needs body work because I thrashed it for like 2 months when i was younger but it runs like a charm. i consider myself lucky to have a good running car and probably abuse driving since i know Ive driven well over 3000 milers since i replaced lim gasket and have driven quite a bit since that. i let it warm up in the summer never mind the winter. i don't get in the habit of beating on it at all and it stays below 3g if it even reaches that most of the time. A reliable good running engine has always been something to consume my mind.