Brake pedal is hard before starting

[tmkassin]

On my 1992 LT1 the brake pedal is hard to depress before starting. The vacuum is obviously leaking down as the car sits. My question is, Is there a check valve that could be going bad or do I have to replace the whole brake booster? Thanks, Tom

 

[dogfish246]

Did you try to see how bad the leak is?

Try this: With the car on, press and hold the break pedal hard enough that you are comfortable pressing it. Then see if after 30 seconds if the pedal travels toward the firewall...

Report back:cool

 

[tmkassin]

Brakes work fine once the car is running. I figured out where the check valve is...Duh! That is the first thing I suspect.

 

[joshwilson3]

Brakes work fine once the car is running. I figured out where the check valve is...Duh! That is the first thing I suspect.

Where is the check valve, and how do you test it?

 

[tmkassin]

The check valve is the little plastic coupler that the vacuum line plugs into on the booster. You can get a new one at the HELPS counter at most auto part stores. Remove it and try to blow through it from the manifold side. It should not allow any passage in that direction.

 

[joshwilson3]

The check valve is the little plastic coupler that the vacuum line plugs into on the booster. You can get a new one at the HELPS counter at most auto part stores. Remove it and try to blow through it from the manifold side. It should not allow any passage in that direction.

I will check it out as I've noticed a really firm brake pedal since I've had it.