Eskimo

Ok, so I was driving around in my 93 VX... I do my errands and get in the car to head home. Well, after about 5 miles, my brake pedal pressure is not firm anymore.

When I first tap it, it feels fine... but as my foot applies a steady pressure, the pedal sinks to the floor. I let go of the pedal and re-apply pressure and it's firm at first, but sinks to the floor.

I had to kinda drive with the parking brake for about 10 miles!

Here's what I know when I finally checked it out:
1. I checked the brake fluid level, it's all good. Caps on tight as well.
2. No dripping form the brake lines either, as far as I can see on the ground.

So, what could it be?
-Did the fluid get too hot? (It's only 90 degrees outside... probably ~ 150deg inside the engine bay.)
-Is my master cylinder going bad?
-What should I check for?

Thanks.

Cornershop

the pedal is firm at first..then sinks to the floor...

..i think that means there is air in the lines.
Someone correct me if i'm wrong.

slooowDX

one of the master cylinder piston seals are bad letting the fluid that is supposed to be distributed out into the brake lines back into the resivoir...my car does the same exact thing....pick up another master cylinder...and check out the booster also...if any fluid leaked into it, it could've eatin up the diaphragm inside....HTH

Eskimo

Thanks for the help!

B18C5-EH2

Yep.

Bad brake master cylinder.

Just keep pumping the brakes up when you go to slow down, and when sitting at lights just keep the e-brake on rather than trying to stay still with the brakes and having the pedal sink.

Just remember that RS master cylinder and booster we talked about Eskimo - it works killer in my car.

Cosworth

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[Modified by Cosworth, 11:03 AM 5/20/2002]