I thought it was me -
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
I thought it was me -
But it happened again!
Yesterday, driving my 91 (auto) coming up to a stop light, the brakes felt stiff, like I had blown another booster. I let up on the pedal and they went back to normal. It did not happen again under any condition, hard brake, slow, soft pedal. Ok, it's my imagination.
But today on my way to work, it happened twice. Then the brakes went back to normal. I cannot make it happen, again under any braking conditions.
I did not see any cracks in the booster, nor hear any vacuum leaks.
All 4 calipers were rebuilt in the last 3 months, the brake fluid is new through out the system, there does not seem to be any fluid leaks that I can see.
Any one out there with some ideas?
Thanks in advance for the help
Subman
Yesterday, driving my 91 (auto) coming up to a stop light, the brakes felt stiff, like I had blown another booster. I let up on the pedal and they went back to normal. It did not happen again under any condition, hard brake, slow, soft pedal. Ok, it's my imagination.
But today on my way to work, it happened twice. Then the brakes went back to normal. I cannot make it happen, again under any braking conditions.
I did not see any cracks in the booster, nor hear any vacuum leaks.
All 4 calipers were rebuilt in the last 3 months, the brake fluid is new through out the system, there does not seem to be any fluid leaks that I can see.
Any one out there with some ideas?
Thanks in advance for the help
Subman
Thread Starter
Burning Brakes
Joined: Jul 2003
Posts: 873
Likes: 2
From: Whittier ca
I did a quick test on the vacuum to the booster. Right after start up with engine at idle vacuum is a 21 inches. After a few minutes, vacuum drops to 20 - 20 1/2. When I depressed the brake pedal, vacuum dropped to 14 - 15 " and the engine increased RPM by 200 to 300. Let off the brake and vacuum returned to 20 1/2" and idle returned to 700-750.
I by passed the booster connection and checkd the manifold vacuum. 20 1/2".
I did a seach on testing the booster holding vacuum and found my MightyVac may not do the job.
I don't hear the usual hissing sound of a leaking booster, but I am getting older so my hearing may not be all it should (LOL).
I really need to get this diagnosed ASAP as I am supposed to be leaving Friday after work heading for Vegas.
Thanks for any thoughts
Subman
I by passed the booster connection and checkd the manifold vacuum. 20 1/2".
I did a seach on testing the booster holding vacuum and found my MightyVac may not do the job.
I don't hear the usual hissing sound of a leaking booster, but I am getting older so my hearing may not be all it should (LOL).
I really need to get this diagnosed ASAP as I am supposed to be leaving Friday after work heading for Vegas.
Thanks for any thoughts
Subman
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
Just curious, have you looked at the pads lately? Is any of them worn much more than any of the others? Any excessively (brake pad) dusty wheels? (just asking because of a vehicle I worked on recently had a piston that would stick in one of the calipers)
Was the master cylinder changed out?
Was the master cylinder changed out?
