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JWXR7
04-18-2003, 12:02 PM
I had to brake hard yesterday, now my pedal goes halfway to the floor before it does anything, then it feels like only the front passenger side is working. If I pump the brakes w/hood open and watch brake resev, the level goes up as I pump. Then the abs pump sounds like it runs and brings the level back down to normal. I can find no leaks, is my master cylinder messed up or something? Any body have any ideas? please

LJGriggs
04-18-2003, 01:15 PM
Do you get any warning indicators flashing on the instrument panel? (either the ABS or Brake or both?) If you got on the brakes hard, did you feel the antilock kick in (rapid pulsation)?

JWXR7
04-18-2003, 11:47 PM
No, I don't have any warning lights from anything, and I didn't see any warning lights flash at any moment during brake use.

I had pretty good grip when I jumped on the brakes so I didn't trigger the abs. So, No I didnt feel the pump pulsations that time because no slippage, but I have had the abs function when it was rainy and icy out earlier this spring and had no problems.

Mike8675309
04-19-2003, 08:23 PM
Have you done any brake repairs with the vehicle in the past?

On an 1989 vehicle I would be real suspicious of the ABS Brake Accumulator. This is a device that stores brake pressure created by the ABS pump through the use of a rubber diaphram seperating brake fluid and Nitrogen gas.

If the rubber diaphram was to become damaged, or the nitrogen gas was to escape (both of which happens due to the rubber degrading over time), your brake system would instantly develop an additional fluid capacity due to the empty space once filled by nitrogen gas.

Symptoms of this failure are:
Brake pedal travel is too much, yet brake fluid level is fine.
Brake fluid level decreases dramatically, but no leak is visible.
ABS Pump runs during each brake application rather than only after about each 10 brake applications.



http://www.frontiernet.net/~miketoni/images/tbird/absactuator.jpg

JWXR7
04-19-2003, 10:37 PM
Two years ago I put new pads on the back, and last summer I blew the line going to the back brakes just in front of the rear wheel, so I replaced that line.
I've suspected the accumulator before because the pedal has felt wierd for a while. Like before this current problem, if I'm at a stop light holding the brake, the pedal would sometimes slowly go towards the floor. Think it could have blown out all the way finally? But that seems like it would effect all of the brakes as a unit. Mine feels like only the front pass. side is working but rear could be working too.
Does my car have a 3 channel abs system where the rear is treated as one unit? It must because there is only one line going to the back. I'm trying to figure out the distribution from the master cylinder, like can one section go out and leave another as a back-up for safety? I know some cars have it so they are diagonal set-ups or something.

Mike8675309
04-19-2003, 11:48 PM
I'm not sure what's happening with your feeling of brakes on one wheel, or on the resevior level changes.

Our brake master is very different from normal brake masters. There isn't a front and back. It's FL, FR, RR, RL. All ports are under the same pressure by the main ABS pump. Note that the ABS pump is what also provides the power assist.

I'd start with a brake inspection all the way around. you could have multiple issues. And blowing hard brake line makes me suspcious of some sort of contamination in the hydraulic system. I suppose it's possible you have a master cylinder failure in the brakes. You might also have a bad caliper on one side up front giving you the feeling that it is grabbing better than others.

Unless you can find something obvious, I'd start with flush the whole brake system with fresh, clean brake fluid. Replace any obviously bad brake components, and then see how it performs.

If the pedal isn't firm right away I'd be thinking a problem with the master cylinder somehow jammed into the bore, or the bore of the cylinder is damaged. But these are all guesses using basic logic. I've no experience with such a problem.

JWXR7
04-20-2003, 06:09 PM
I just checked the caliper on the side that doesn't feel like it is working and it seems free and the piston moves like normal. Also when I changed the back brake line last year that blew, I flushed the system at that point with new fluid, but the front still has old fluid in the lines and such.
I did notice something today driving in the rain. If I slide the only wheel that feels like it has any brake power the abs kicks in and all four brakes seem to work pretty much equally during the abs usage. hmmmm??!!

Mike, I think a full flush wouldn't be a bad idea, and go from there.

Can brake codes be pulled without a code reader like with our eec tests?

JWXR7
04-22-2003, 05:49 PM
okay, yesterday I began flushing the system from the back right and left. I had huge amounts of air in the lines. From where? Maybe the accumulator nitrogen escaped into the system when I jammed on the brakes last week, not sure but I know the accumulator didn't pass the driveway test (the pump kicked on during the second pump). So I figure if I can get all the air out and put a new accumulator on then I will be back to normal, I hope.
Can some of the air be bled at the master cylinder somehow? I've already gone thru two quarts of brake fluid and I havent even got all four wheels done yet.

I found an 89 xr7 at the local junkyard, so if it comes down to it I can get the whole abs assembly for $225.

JWXR7
05-03-2003, 08:13 PM
ok. i changed the accumulator today and went to bleeding the brakes. i started w/ the right rear and everything was fine as with the left rear and left front. when i bled the right front, it didn't pump much fliud out. also, after i cracked the bleeder valve, it sucked fluid back into the caliper like there was a vacuum on the line. and the pedal feel isn't getting any better.

went out a few hours later and the rf brake bled like normal.?? The pedal is still feeling the same and I noticed that it sounds wierd when I pump the pedal. I'm started to go with the idea that I blew a seal in the actuator or jammed the mastercylinder.

Camp89
06-17-2003, 05:47 PM
My husband has attempted to put new brakes on our 89 SC. He test drove it around the block and now the brakes are smoking like crazy, whats up with that?

LJGriggs
06-18-2003, 09:32 AM
What did your husband replace? Just pads? Pads and rotors? Did he open the bleeder valve while compressing the caliper piston? Did he do the front and rear brakes? Is it smoking from all wheels, or just some of them?

This could be just some "gunk" on the rotors that is burning off, or it could be a caliper seizing on the rotor. Might also be brake fluid leaking from the bleeder valve onto a hot rotor (if the bleeder valve was opened in order to compress the piston).

Try spraying the rotors with some brake cleaner and see if you still get the smoke...