Driving to work this morning in heavy traffic and randomly my brake pedal would get so hard I could barely push it and as quick as it happened it would go back to being normal again. Brake fluid was flushed a month ago and looking at the past service records it looks like it may have been done last year but can't be for certain. Only thing I can think of is the master cylinder or a caliper or rear cylinder acting up.
Confirm my thoughts on dying master cylinder
- Thread starter cashmoney
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JeepKiller
New member
If there isn't any brake fluid leaking from the calipers and you know that there is NO air in the lines then yeah it's gotta be your master cylinder.
JeepKiller
New member
When mine died it completely locked up.
KidVermicious
New member
No expert here either, but I think this is right. In my experience anyway, a soggy pedal has been a leak or bypassing master cylinder, a pedal that gets too firm is the booster. Check for a vacuum leak and if not maybe you've got a bad booster.
Hmm. I noticed yesterday the idle was a hair rougher than I seemed to remember but chalked it up to being low on fuel yesterday.
LittleCaesar
New member
Check valve in the booster more than likely. Replace the grommet as well.
Dephcon
New member
Not to thread jack from the OP, but I have an issue that is somewhat related. Basically, i have to pump the brakes to build up pressure in the peddle. For instance, when I first press the peddle to stop, it goes almost to the floor. If I release and press the peddle again, the brakes grab higher up (peddle doesn't have to move as far). Also when the engine is first fired up and the idle is higher or if driving up a hill with a higher RPM this is not as much of an issue, no inital pump of the peddle is required and the brakes grab right away. I have been trying to figure out if its the master cylinder, the booster, the vacuum check valve or just a vacuum leak.
It was suggested to me that it was possibly the rubber grommet thats on the peddle shaft that goes thru the firewall into the booster, which seems like a possible cause.
Sorry for the thread jack, hoping someone has an answer since this is somewhat related.
It was suggested to me that it was possibly the rubber grommet thats on the peddle shaft that goes thru the firewall into the booster, which seems like a possible cause.
Sorry for the thread jack, hoping someone has an answer since this is somewhat related.
nevada
Senior Member
if you have a vacuum booster, I would suspect it, or the check valve/grommet is leaking.
do yours have the regular MC, or the integrated electronic unit?
nevada
Senior Member
rear brakes are out of adjustment.
Dephcon
New member
This was indeed it. Adjusted both rear brakes and the issue went away. Thanks for the advice.
LittleCaesar
New member
After I saw you are in Austin I was hoping it was just the valve. Usually this only happens in colder climates.
The way I have checked boosters is to turn off the car and pump the pedal five times. With each pump the pedal gets firmer. Then hold the pedal and it should remain stiff.
I can't think of any other part of the braking system other than the booster which would cause the problems you are having.
The way I have checked boosters is to turn off the car and pump the pedal five times. With each pump the pedal gets firmer. Then hold the pedal and it should remain stiff.
I can't think of any other part of the braking system other than the booster which would cause the problems you are having.
And now I've lost all power brakes. Yee haw!!!
I can lightly put my foot on the brake pedal and hear air moving and the pedal firms up quick with the engine running. Glad I'm working an odd job today for a buddy. Money should pay for a new booster. Probably going to do the master cylinder, rear cylinders, and tundras while I'm at it. No sense in half assing it.
I can lightly put my foot on the brake pedal and hear air moving and the pedal firms up quick with the engine running. Glad I'm working an odd job today for a buddy. Money should pay for a new booster. Probably going to do the master cylinder, rear cylinders, and tundras while I'm at it. No sense in half assing it.
