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Followup To
Question -
Last week I noticed that my brake pedal was getting very hard while driving in stop and go traffic. I also noticed that the brakes were not releasing completely. With the car in drive, it wouldn't start rolling. If I put it in neutral it would stop like the brakes were being applied, and they weren't. After a while, there was no braking, the pedal went all the way to the floor. I loosened one of the brake lines at the master cylinder and pumped the pedal. No brake fluid came out. I waited a little while, and brake fluid started to come out just from gravity. I tightened the brake line back up, and the brakes worked normally for the rest of the day. The next weekend, I bled the entire system, thinking there might have been some debris somewhere causing the pressure not to release at the calipers. On my next drive, I noticed the pedal getting hard, and the brakes not releasing again. I removed the fuse, relays, and multipin connector to the ABS system to see if that would help. It didn't. So, I stopped and let everything cool down and it's OK for now. What do you think is the problem? The car has 220K miles on it. I'm a pretty good diyer, so this has me baffled with a pretty unsafe problem. Any help, I would really appreciate. Thanks, Pete
Answer -
Hello Pete,
When you say "hard" pedal...do you mean hard to press or hard to stop?
You might consider checking your master cyl.
losing the pressure and fluid in output ports to your brake lines means failed master cyl....it can do strange things when the m/c goes south.
Look closely for fluid leaks...sometime they leak internally.
At 220,000 a failed m/c is very normal.
Think....just for a slight moment....how many thousands and thousands times you have pressed that brake pedal...
You may want to take a peek at your brake booster unit too...if it fails it could keep your brakes on....lastly,check your calipers to see if any are frozen...or maybe your pads are rusted into the caliper and not releasing the disc.
Let me know what you find.
Bilbo
Thanks for your response Bilbo. Yes, the pedal gets hard to push, with virtually no travel before the brakes are applied. What's the best way to check the brake booster? That seems likely to me to be the problem, as it the pedal feels like it does when you pump the pedal without the engine running a few times. You know after a few pumps to use up all the vacuum, there is virtually no travel in the pedal and it becomes very hard. I don't have any leaks, I dom't think, because I haven't had to add any fluid and the level stays constant. The level actually got higher in reservoir when the problem occurred. I think the brake fluid boiled when the brakes got so hot, since the level was higher. Because the problem is intermittent, I guess it could be the calipers. However, it would seem odd to me that both front calipers would start having the same problem at the same time, since the car does not pull to one side or the other. I would like to know the best way to check the booster, since my research and your comment make that seem likely. By the way, I had no trouble at all bleeding the brakes when they were cold. I did them in the order recommended in my Chilton manual for the ABS system.
Thanks again,
Pete
AnswerHello Pete,
Testing the booster is kinda easy...it's vacuum operated and it depends on the engine to create the vacuum...a poorly running engine can effect the brakes...too little vacuum..
take the hose that feeds the booster...put the end that was attached to engine in your mouth...suck on it...see if it holds the vacuum charge that you created...with your mouth...also there may be a check valve on the hose...check it out...with vacuum hose blocked... start car and feel engine vacuum with your hand...it should be a good draw...
I still think you should look at ALL your brake componants...lift car wheel...test caliper operation...ALL 4 WHEELS,..PETE
You might have mutiple problems...I hope not.
The master cyl. should be looked at carefully.
Bilbo
