Everything was fine. The Vette just sat for about three weeks and I get back in my 90 coupe and the brake pedal is stiff. Like it is getting no assist. Did the booster just up and die with no warning? I'm sure the car was angry for me not paying it more attention. Should I whack the booster with a mallet, spray something with WD40 or duct tape the canister? Your views and opinions please.

Maybe somebody dropped a Viagra in the brake fluid?

Many years ago I had a similar problem on another car, and it turned out to just be a bad check valve on the booster. Worth a look, anyway - it would be a cheap fix.

I agree, check the check valve. It's the bit that the hose plugs into on the booster.

As a rule of thumb:

Stiff pedel = booster issue
Soft pedel = master cylinder issue

Looks like I broke the check valve trying to inspect it. I tried to pry it off and the plastic housing broke. How does it come off? It looked like it just pried away.

Well I got it out but a piece fell into the booster. Am I in trouble or what?

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Normally you should be able to work it out with a bit of gentle pulling and twisting. Perhaps it was brittle from age. But at least now you have an excuse to buy one! Make sure it comes with a new grommet too, if not, get one. Inspect the hose inside and out and replace it too if there's any doubt. Make sure and use a suitable hose intended for such a purpose and one that won't get sucked shut. Hopefully you won't have to invest in a booster to get your brakes back up to snuff.

I ordered the check valve from Ecklers. Couldn't find the grommet but the old one will do. My wife has a feild day with stuff like this. I go to check something and break it. I'm bracing myself for the booster though, just in case.

Bummer about it breaking - I'd guess that if it was that brittle, there's a good chance it was the culprit. Maybe you could get the broken piece out with a shop vac once you remove the grommet?

I took the house vac and attached a small piece of hose to an extension.(That's where the tape came in handy) Couldn't get deep enough. Never could ...........

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How big was the piece that broke off? Maybe you can use some tweezers or needle nose pliers to pull it out.

Matthew

It fell into the booster canister. No tool access to where it is.

You probably had to replace it anyways. They can be checked with a vacuum pump.

Have someone hold the pedal down a few inches, and try to pull a vacuum on the booster check valve.

Got the check valve today and replaced it. No improvement. I did notice that the brake fluid was all the way to the top in the rear resevoir so I removed a little fluid and ran it. No improvement. Would bleeding the system accomplish anything or am I wasting my time? Whats next? Booster? Central Coaster; What is the reaction on the pedal when you pull vacuum through the check valve? Would I be able to feel vacuum pressure in the line that connects to the check valve? Any good leads on replacement boosters? Thanks.

Tommy T.

Pushing the pedal down a bit opens the air path to the diaphram in there. If you don't do this, then pulling a vaccuum won't check the integrity of the diaphram. I hope that makes sense. Think of what the manifold vacuum would do if it always was open to the front side of the diaphram, it would give brake assist 100% of the time with or without pedal.

So hold the pedal down a bit with a 2x4 or something and hook your vacuum pump directly to the booster check valve and pump away. It will take awhile to pull a vacuum because it's a fairly large volume, and because the diaphram will move to engage the brakes a bit.



High fluid level in the rear reservoir and low in front indicates a bad master cylinder (bad primary seal). The front circuit pressure may be leaking into the rear circuit. This should trip the brake warning light. It would also result in little or no front brake, just rear. Not the same feeling as a hard pedal, but the results would be the same, crappy brakes.

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Interesting... My front and rear levels are different.

I got my '98 Jimmy in the air now, both pistons out of the bores left and right, rubber line disconnected, lookin' for reasons the driver's side is binding just a little.

Hardly any fluid dripped (clear yellow) when I disconnected the line at the caliper. ??? Pulled the M/C cap, to let air in, and still hardly any fluid. Backed up further, to the proportioning valve, and disconnected it, and only few drops (clear yellow) again. ???

(nothin' like BOOSTIN' someone's thread huh)

So what makes one side not let fluid pressure off of the caliper???

Different levels are ok... but if you suddenly find one side dropping, and the other side rising, that's a problem.

Go buy a booster and put on it. This is what I am doing now with mine (same problem). If the break pedal is hard like you say (as is mine) I imagine if you pull the hush panel down and start the car you will hear the vac leak from the booster in the car. Lay down under the dash and press the brake while it is running and hear for the hiss sound.

Has the car started running wierd about the same time you had brake problems due to the vac leak?