Is my powermaster failing?

[ez at nova]

When I was out yesterday I noticed that when I stabbed the brake very quickly, the BRAKE light came on for a few seconds. Braking did not seems to be gone or very poor or anything (well, for a GN, hehe). I made a vew more quick jab stops and could get the light to come on again. Each time it would go away in 5 -15 seconds. I was always able to get the BRAKE light to come on if I pulsed the pedal like 5-7 times (which is supposed to happen, I've read), but I've never had the light come on when I hit the brakes while driving. I'm scared now that I may have brake failure. I'd rather not be doing 110+ at the end of the track and then have no brakes!

 

[Scott231]

That is the infamous (and very well documented) Accumulator failing warning sign. Unfortunately, the Accumulators have gone way up in price. Like $208.64 retail!!

Hello vacuum brakes! Wow, that is one way to eliminate the demand for a product.

 

[granitestategn]

Try this

I haven't done it, but I heard you can get a whole rebuilt powermaster unit from Autozone for under $200. Eat the core charge. Steal the accumulator off of it. Put what's left on the shelf for when the rest of it shoots craps. Or go to the junkyard and get a pedal off a vac brake car and convert. I did mine and don't regret it.

 

[ez at nova]

DOH. Ok, but am I going to die on the road with no brakes all of the sudden or anything? I planned on racing Friday.
Also, what's the $$ cost if I were to use vacuum brakes? Isn't that a much harder job than repairing the powermaster?
If I were to get a new accumulator, is it as easy as taking off the old one and putting on a new one?
Thanks

 

[TurboDave]

Originally posted by ez at nova
DOH. Ok, but am I going to die on the road with no brakes all of the sudden or anything? I planned on racing Friday.
Also, what's the $$ cost if I were to use vacuum brakes? Isn't that a much harder job than repairing the powermaster?
If I were to get a new accumulator, is it as easy as taking off the old one and putting on a new one?
Thanks

I wouldn't let it go any longer. It will eventually become more serious, and then you'll have a real problem on your hands. It's trying to tell you something. Heed the warning.

Check with Kirbans, they still had accumulators at a moderately reasonable price the last time I checked.

DO NOT buy accumulators direct form GM, any GM. They'll rake you over the coals pricewise.

 

[ez at nova]

Is there procedures for replacing the accumulator somewhere? Is it something that's easy to do?
I guess I can't complain TOO much since this one has 163k miles on it. Are we talking about the accumulator ball piece? That's probably all my problem is?

Thanks!

 

[TurboDave]

Replacing the accumulator is SUPER easy. With key off, pump brake pedal at least 15-20 until it gets real hard, this releaves the pressure from the system. Put a small rag under the accumulator and then unscrew it from the master cylinder.

CAUTION: don't let any brake fluid drip on your paint.

Screw the new on in, turn the key on. The PM motor will run for a while to re pressurize the system. Start pumping the brake pedal slowly and this will get the system recharged. The pedal may go to the floor the first few pumps. So you want to make sure everything is OK before actually driving the car.

 

[ez at nova]

Wow, sweet. I think it's worth the $ for me to just get that then rather than fooling with the whole conversion to vacuums. (I'm a vendor's dream, haha) I suppose this is all on the assumption it's just the accumulator that's bad. Any way I can/should diagnose more to find any other problems, or is this pretty much 99% sure the sole problem here (I guess it may be a typical thing).
Any oppinion on the Autozone accumulator VS one from, say, Kirban?

 

[ez at nova]

more diagnosis

Ok, I diagnosed the problem a bit more. When I press the brake 10-15 times with the car off to depressurize everything, then turn the key to "ON", it takes 10-15 seconds for the motor to stop running. It does NOT recycle the motor on if you let it sit, so there is no leak wherever that would indicate. With the key still in "ON", if I stab the brake ONCE with medium/quick pressure, teh BRAKE light comes on and goes off in 1-2 seconds. If I press the brake very slowly and lightly, it will take 3-5 times for the light to come on and go off. The pedal definitely does not feel "hard".
I'm hoping and guessing that it's the accumulator, so I ordered one (Kirban did have a good price). Hope I didn't waste my money!
Input?

 

[TurboDave]

Re: more diagnosis

Originally posted by ez at nova
Ok, I diagnosed the problem a bit more. When I press the brake 10-15 times with the car off to depressurize everything, then turn the key to "ON", it takes 10-15 seconds for the motor to stop running. It does NOT recycle the motor on if you let it sit, so there is no leak wherever that would indicate. With the key still in "ON", if I stab the brake ONCE with medium/quick pressure, teh BRAKE light comes on and goes off in 1-2 seconds. If I press the brake very slowly and lightly, it will take 3-5 times for the light to come on and go off. The pedal definitely does not feel "hard".
I'm hoping and guessing that it's the accumulator, so I ordered one (Kirban did have a good price). Hope I didn't waste my money!
Input?

Perfect troubleshooting!! Points right straight at the Accumulator.

 

[ez at nova]

I looked in the light today, the grey switch looks fine. The fluid is definitely not low. The only thing that concerns me a bit is that when I took the resevior cover off, one of the "indented pits" in the rubber seal part looked all contorted and sqeezed in. the smallest one was sort of pushed up too. The whole thing was sealed fine around the lip though. Is this a concern?

 

[TurboDave]

Originally posted by ez at nova
I looked in the light today, the grey switch looks fine. The fluid is definitely not low. The only thing that concerns me a bit is that when I took the resevior cover off, one of the "indented pits" in the rubber seal part looked all contorted and sqeezed in. the smallest one was sort of pushed up too. The whole thing was sealed fine around the lip though. Is this a concern?

Nope, not really. Just remember the half of the reservoir closest to the engine should be fairly low so don't fill that side up.

 

[Black Box]

OK here's a question to add to this....is there a 'general' time frame as to how long the failing accumulator will exhibit this problem before failing completely? 10 miles? 500 miles? My car has the exact same symtoms as ez's. I wanted to take it for a ride today but if I'm gonna lose brakes completely, then it's staying in the garage. It's got 31K miles on it....not that would make any difference at all, a failing part is a failing part.

Thanks,
Steve

 

[ez at nova]

If it helps diagnose a time frame, mine has 163,000 miles on it. It is teh "warranty replaced" bulb though, so I don't know when this one was actually put on. I'm sur eit has at least 100,000 + though.

 

[TurboDave]

Originally posted by Black Box
OK here's a question to add to this....is there a 'general' time frame as to how long the failing accumulator will exhibit this problem before failing completely? 10 miles? 500 miles? My car has the exact same symtoms as ez's. I wanted to take it for a ride today but if I'm gonna lose brakes completely, then it's staying in the garage. It's got 31K miles on it....not that would make any difference at all, a failing part is a failing part.

Thanks,
Steve

There's no rule of thumb for time frame. BUT, the longer you let it go, the more serious the damage it can cause. Like the man says. You can pay me now, or pay me later.

Paying for an accumulator now at <$100 is better than having to put in a whole new PM.

 

[ez at nova]

UPDATE

I put the new accumulator on and the problem seems to have been cured! The brake pedal feels totally different.... less sloppy and there's more resistance now. Now the light doesn't come on when I stab the brakes, and it takes 5-7 pumps for it to come on then go off.

Thanks guys