Weird brake issue on '91 DB1 w/ ABS.
06-12-2009, 07:01 PM
#1
Weird brake issue on '91 DB1 w/ ABS.
About 3-4 months ago my brake pedal started getting mushy and would go to the floor, so like I did on the last few integras I've owned...I replaced the master cylinder. The problem went away, but I noticed that I had to press the brake pedal a little farther than normal before the brakes engaged. I didn't see it as a problem, the brakes worked great and felt good so I drove it.
Two days ago my dash brake light comes on. I thought the brake light was for just the parking brake, and since my interior is gutted I figured I bumped or spilt something on the parking brake switch so I ignored the light. Completely forgot that light is connected to the master cylinder brake fluid reservoir.
Earlier this afternoon I got in my car to run to town, and instantly noticed the pedal sink to the floor...the brakes worked but barely, the pedal literally had to be to the floor for the car to not roll down my driveway. I checked all the lines I could see, no leaks. I checked the calipers, no leaks. I checked the reservoir...empty. I filled it(and remembered that this is what the brake light as trying to tell me 2 days ago), bled all the calipers one at a time starting at the rear/left, then rear/right, then front/right and then front/left. The rears put out no bubbles, but put out a very dark brown fluid with debris which has me concerned a little. The fronts put out a small mount of bubbles, and a lighter brown fluid with little or no debris. I bled each caliper until no bubbles were present at all, making sure the reservoir stayed full, making sure my fiance pumped the pedal 10 extra times per caliper after the last bubble to guarantee most/all the air was out of each line.
After this I decide to test drive the car. Pedal still sinks to floor when car is on, but holds sufficient pressure when car is off. The brakes do work, but not until the pedal is literally to the floor. I'm afraid to drive the car at this point, it feels severely unsafe.
I don't know if my new(remanufactured) master cylinder went bad in only 3-4 months, if there's some sort of super-disguised leak that is damn near impossible to find, or if my booster is bad. To me it seems like the master cylinder again, but the fact that the reservoir was completely empty has me concerned. This is our only car and we both work...so we're screwed if I can't get it fixed.
Any opinions/suggestions/ideas?
Two days ago my dash brake light comes on. I thought the brake light was for just the parking brake, and since my interior is gutted I figured I bumped or spilt something on the parking brake switch so I ignored the light. Completely forgot that light is connected to the master cylinder brake fluid reservoir.
Earlier this afternoon I got in my car to run to town, and instantly noticed the pedal sink to the floor...the brakes worked but barely, the pedal literally had to be to the floor for the car to not roll down my driveway. I checked all the lines I could see, no leaks. I checked the calipers, no leaks. I checked the reservoir...empty. I filled it(and remembered that this is what the brake light as trying to tell me 2 days ago), bled all the calipers one at a time starting at the rear/left, then rear/right, then front/right and then front/left. The rears put out no bubbles, but put out a very dark brown fluid with debris which has me concerned a little. The fronts put out a small mount of bubbles, and a lighter brown fluid with little or no debris. I bled each caliper until no bubbles were present at all, making sure the reservoir stayed full, making sure my fiance pumped the pedal 10 extra times per caliper after the last bubble to guarantee most/all the air was out of each line.
After this I decide to test drive the car. Pedal still sinks to floor when car is on, but holds sufficient pressure when car is off. The brakes do work, but not until the pedal is literally to the floor. I'm afraid to drive the car at this point, it feels severely unsafe.
I don't know if my new(remanufactured) master cylinder went bad in only 3-4 months, if there's some sort of super-disguised leak that is damn near impossible to find, or if my booster is bad. To me it seems like the master cylinder again, but the fact that the reservoir was completely empty has me concerned. This is our only car and we both work...so we're screwed if I can't get it fixed.
Any opinions/suggestions/ideas?
Last edited by socialistic; 06-12-2009 at 09:46 PM.
06-13-2009, 09:16 PM
#2
Re: Weird brake issue on '91 DB1 w/ ABS.
Just bought a new master cylinder, a mityvac kit(because they kick *** and make the bleeding a 1person job), and some brake fluid.
So I get home, pulled the master cylinder off...fluid all over the lower front half of the brake booster and over that rear x-member/steering rack. Paint is peeling off the booster and the x-member. There's also signs that fluid has in fact gone in to the brake booster, the o-ring/gasket in the brake booster hole was wet with fluid, and the inner diameter of that hole had the black paint peeling from the lower half. This has definitely been a leak that has lasted probably since I did the master cylinder job 3 months ago, and definitely explains why the reservoir emptied.
So what does this mean exactly? Master cylinder is bad? Brake booster is bad? Both are bad?
EDIT: Is there supposed to be a gasket or seal on the piston end of the master cylinder around the piston, or just that rubber gasket in the brake booster hole? My current master cylinder doesn't have one, and the new master cylinder didn't come with one from a quick look in the box. When looking at that end of either master cylinder, around the piston is one of those metal snap-rings and nothing else. There is a weird rubber o-ring/gasket/seal type of thing that was in the brake booster hole, about the size of a half dollar give or take. There was a part number on it, and on one side it said "M/P SIDE". Is that the only gasket that should be there?
EDIT2: Went ahead and wiped up all the leaked fluid, bench-bled the new master cylinder and installed it, bled all 4 calipers, topped off the reservoir and wiped down the master cylinder and brake booster again to get any spilled fluid I missed earlier so I could identify new leaks.
Test drove it about 1mile round trip, brakes work great. In fact they seem to be working better than they did after the last master cylinder replacement 3 months ago. I checked the bottom/front half of the brake booster and the underside of the master cylinder, no fluid. Drove the car to town, gassed it up, drove to taco bell, idled and ate my food, drove home...brakes still working great.
Looks like I just got a faulty remanufactured master cylinder from autozone. 1 out of the 4 or 5 I've purchased from them over the years is not bad I guess. Won't keep me from buying another unless this new one blows up anytime in the near future.
So I get home, pulled the master cylinder off...fluid all over the lower front half of the brake booster and over that rear x-member/steering rack. Paint is peeling off the booster and the x-member. There's also signs that fluid has in fact gone in to the brake booster, the o-ring/gasket in the brake booster hole was wet with fluid, and the inner diameter of that hole had the black paint peeling from the lower half. This has definitely been a leak that has lasted probably since I did the master cylinder job 3 months ago, and definitely explains why the reservoir emptied.
So what does this mean exactly? Master cylinder is bad? Brake booster is bad? Both are bad?
EDIT: Is there supposed to be a gasket or seal on the piston end of the master cylinder around the piston, or just that rubber gasket in the brake booster hole? My current master cylinder doesn't have one, and the new master cylinder didn't come with one from a quick look in the box. When looking at that end of either master cylinder, around the piston is one of those metal snap-rings and nothing else. There is a weird rubber o-ring/gasket/seal type of thing that was in the brake booster hole, about the size of a half dollar give or take. There was a part number on it, and on one side it said "M/P SIDE". Is that the only gasket that should be there?
EDIT2: Went ahead and wiped up all the leaked fluid, bench-bled the new master cylinder and installed it, bled all 4 calipers, topped off the reservoir and wiped down the master cylinder and brake booster again to get any spilled fluid I missed earlier so I could identify new leaks.
Test drove it about 1mile round trip, brakes work great. In fact they seem to be working better than they did after the last master cylinder replacement 3 months ago. I checked the bottom/front half of the brake booster and the underside of the master cylinder, no fluid. Drove the car to town, gassed it up, drove to taco bell, idled and ate my food, drove home...brakes still working great.
Looks like I just got a faulty remanufactured master cylinder from autozone. 1 out of the 4 or 5 I've purchased from them over the years is not bad I guess. Won't keep me from buying another unless this new one blows up anytime in the near future.
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