Hey Guys,
Just realized what a problem I've had for years (and maybe 70k miles) is. When I push the brake pedal really hard the brake booster actually separates at the seam that runs circumferentially around at the very top and makes a squealing sound. Must be suction I suppose but I didn't test for that. I just ignored that sound years ago and adjusted how I brake so that it didn't make the sound and forgot about it. Now it seems to be getting worse. I wonder if sealing that seam with silcone or something would be just fixing the sympton. Do I need a new booster? It's all original brake booster and master cylinder with 260k miles on it.
Robb

Well I took the advice and sealed the seam of the booster with a bead of red hi-temp RTV and the noise is gone. Don't know if I am just bandaiding a bigger problem and the booster is going to come flying apart during hard braking sometime in the future but it's fixed for now...
Robb

Hi Rob,

Thanks for posting. I'm going to give that a shot too, then and hope it holds.

Marty

Hi Robb,

I have a similar problem with the brake booster in that when the brake is depressed, I get a pulsating idle especially when the car is not warmed up with the application of the brake - as in the case where you're waiting for a light to change. The pulsations can get so violent (say 400 rpm - near stall to 1300 rpm) that you are actually forced to put the car in neutral to permit you to release the brake which stops the engine rpm pulations.

The car is also a 93 with 175K.

When you initially start the car, it runs very rough and I've changed the intake gasket, replaced the AMM, cleaned the throttle body and IAC and checked for vacuum leaks. I have not checked for a leaky injector, however. After about the first 20 seconds, the engine smooths out and runs well with no other problems other than the pulsating idle with the brake depressed. I'm not sure if the two problems are related.

Philvo got me a replacement booster which could go in soon and hopefully take care of this issue.

Let us all know what you've come up with. I'd certainly prefer sealing the perimeter of the two booster halves with sealant as opposed to an R&R.

Marty Wolfson

I had a whistling sound from my brake booster when the brakes were pushed extra hard. I sealed the edge where the two halves of the circular can with GE Silicone II about five years ago and haven't heard a whistle since. I was careful to get the seam under it with caulk too.