No pedal pressure
Thread Starter
Burning Brakes
Joined: May 2000
Posts: 1,160
Likes: 10
From: Nashville TN
No pedal pressure
OK, this is on a 73 Nova I just purchased but I think the same principles apply and this seemed like the best place to ask. It has disk brakes in the front and drum in the rear. The person I pruchased the car from snapped some lugs on the right front wheel and the wheel came off and damaged the caliper and rotor. He replaced the mount, caliper, line, and rotor for that wheel. He said he bleed it after that and the pressure disappeared from the pedal. The car was braking fine before the incident.
So, I replace the master cylinder since it seems to be the culprit. I go to bleed the air out of the system and the left rear drum does not send any fluid out of it. The right one does. The left one looks like it piggybacks off the right. I have replaced the bleeder screws. Now, we get some decent pressure on the pedal when the car is off but when it is running it completely looses pressure and pedal pretty much has to be pulled off the floor.
Any suggestions here? Could it be a bad combination valve? It seems to be an odd coincidence that another part went bad during his wheel coming off inicident. Could it be that the caliper he just got is bad? But what about the no fluid to the left rear drum?
So, I replace the master cylinder since it seems to be the culprit. I go to bleed the air out of the system and the left rear drum does not send any fluid out of it. The right one does. The left one looks like it piggybacks off the right. I have replaced the bleeder screws. Now, we get some decent pressure on the pedal when the car is off but when it is running it completely looses pressure and pedal pretty much has to be pulled off the floor.
Any suggestions here? Could it be a bad combination valve? It seems to be an odd coincidence that another part went bad during his wheel coming off inicident. Could it be that the caliper he just got is bad? But what about the no fluid to the left rear drum?
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
The brake switch may be stuck, does the brake light come on??
To reset it you usually pound really hard on the brakes a couple of times...
either that he didn't bleed it enough, it takes a LOT on new calipers
To reset it you usually pound really hard on the brakes a couple of times...
either that he didn't bleed it enough, it takes a LOT on new calipers
Thread Starter
Burning Brakes
Joined: May 2000
Posts: 1,160
Likes: 10
From: Nashville TN
It does seem to be an issue like that. You can really hear the rear drums moving and the front disks don't appear to be moving at all. The fluid coming out of them is quite week.
Something I noticed though, when you push down the pedal, a stream of fluid shoots out of the front resevoir on the master cylinder but not the rear. Is this a pressure bypass of some sort? Does that mean the pressure I'm supposed to be sending to the front brakes is actually just shooting out of the resevoir.
Something I noticed though, when you push down the pedal, a stream of fluid shoots out of the front resevoir on the master cylinder but not the rear. Is this a pressure bypass of some sort? Does that mean the pressure I'm supposed to be sending to the front brakes is actually just shooting out of the resevoir.
Drifting
Joined: Dec 2004
Posts: 1,714
Likes: 42
From: Austin Texas
I am having the EXACT same problem and thanks to this forum i went out and bought a MITYVAC. you can rent them from autozone...
this helped me troubleshoot the system down to a leaky connection where the front hose connects to the line. to me, it was a valuable tool in this process.
the power assist basically compresses the air trapped in the lines or you have a small leak. with all those parts being replaced i would recheck that area with a vacume guage.
Good luck
this helped me troubleshoot the system down to a leaky connection where the front hose connects to the line. to me, it was a valuable tool in this process.
the power assist basically compresses the air trapped in the lines or you have a small leak. with all those parts being replaced i would recheck that area with a vacume guage.
Good luck
C6 the C5 of tomorrow
Joined: Nov 2000
Posts: 6,665
Likes: 2
From: Twin Cities Minnesota
An easy way to troubleshoot brakes to to clamp off all 4 brake lines. Just use a vicegrip and squeeze the rubber lines closed. Dont smash the lines too hard tho.
If you do all 4 and you have a pedal, it's not the MC nor the lines. Unclamp one line at a time and you can find the issue...
If you do all 4 and you have a pedal, it's not the MC nor the lines. Unclamp one line at a time and you can find the issue...
