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MAJOR PMIII Failure! HELP!!!


Addicted2bass

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Leaving work today im greeted by a large puddle of fluid underneath the TGP. I check the brake fluid....the reservoir is damn near empty. The brakes seemed fine on the way to work and the master cylinder has never leaked before, i check it regularly. Unfortunately this isnt even the worst of it heres a quick rundown of the problems:

 

Master cylinder is leaking fluid at a pretty fast rate, its a fairly steady drip.

The master cylinder makes a loud humming noise, i also heard some sort of gurgling noise as well.

This causes the battery to go COMPLETELY dead in about a minute.

Once the fluid got real low the main ABS fuse blew, once that happens i have no brakes but the MC stops making noise and the leak seems to stop.

There is a bad smell coming from the MC, it can be smelled inside the car as well, but its pretty strong under the hood.

 

Heres a few side notes:

The brakes have been weird ever since i bought the car. They pulsate alot, its not a smooth stop. About two months ago i unplugged one of the plugs on the side of the MC. I believe its for a solenoid inside? There was considerably less pulsation after i did this.

The main ABS fuses (the big one under the hood) has blown on me twice before. Once last summer when i had the car on a charger for about 4 hours and once a month or two ago.

There are no ABS or Brake lights on. Neither have EVER come on. Possibly they were disabled somehow?

The guy i bought the car from (about a year ago) said he replaced the original MC with one from a junked TGP cuz the original was leaking.

 

Im guessing the MC took a shit? I know its common on these cars. Anything else it could be? Im not liking the idea of trying to find a PMIII and i know they are expensive. The car is sitting at my work now. It seems to be holding fluid with the fuse removed, but i cant drive it anywhere like that cuz i have virtually no brakes. Any thoughts or advice would be GREATLY appreciated!!!

 

 

 

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hmmm I'd try and swap the whole unit out for a known good one from a j/y car, or from a member here.

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Problem is finding one. There was a guy in albany with a good one a few months ago. I should have just bought it at the time. Im trying to find his contact info and see if he still has it. Are there any floating around on here?? The other problem is finding someone to swap it out. My mechanic probably wont want to touch it and i imagine its beyond my limited mechanical ability. But as long as i can find one in good working order im sure i can find someone to do the swap, or help me along in doing it myself. I dont really have much to lose at this point since i cant drive the car the way it is.

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http://www.kazmotorsports.com/tpsgarage/TGP/brakes/powermaster.htm

 

the humming noise is the pressure pump for the accumulator running. normally, you should hear this on a regular basis after every few pedal presses. If there's no fluid or the accumulator isn't holding pressure, the pump constantly runs trying to build pressure in the accumulator. A pressure switch tells it when to shut off.

 

Man from the sound of it, you might want to save yourself a lot of headaches and just get a reman. from Prior.

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Any chance that it is a bad accumulator?? I looked over that webpage and replacing the entire master cylinder looks to be well beyond my mechanical abilities and having a mechanic do it seems like it would be pretty expensive. Looks like im stuck between a rock and hard place here. Anything else simple it could be before i go ahead and order the reman unit? I love this car and will put the money into it to have it done right, but id like to rule out all other possibilities before i spend the big bucks.

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PMIII replacement isn't as hard as it sounds, it just requires some thought and it is a bit time consuming for your first time doing it.

 

Replacing the PMIII was the first thing I had to do on my TGP. It wasn't hard, but it was a bit time consuming. I learned a LOT in this process.

 

If you are leaking, your pump housing may have gone bad. The Prior units have a better design and aren't supposed to leak like the Delco ones do.

Good luck

 

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Yea swapping a PM3 isn't hard at all. The hardest part (to understand, at least) is realigning the brake light switch later so that your brake lights don't stay on all the time, but a shop would prolly do that part for cheap (just make sure you tell them to adjust it, not replace it).

 

Removal is literally yanking the brake pedal back to remove the pushrod, draining reservoir fluid (turkey baster or a cheap pump from Autostoned will help), disconnect the wiring, disconnect the 3 brake lines and remove two nuts holding it from the firewall. Install is just the reverse, just make sure you swap over the parts that didn't come with the reman before you try putting it back in (they will be apparent).

 

Follow the bleeding instructions word for word on that page, or if you really don't feel comfortable, have it towed to a garage and have them fill and bleed it.

 

MAKE SURE THE SYSTEM IS DEPRESSURIZED before doing ANYTHING. Press the brake pedal 40 times with the ignition off. Don't forget to keep the car off later so the pump doesn't try to run while it's bone dry.

 

I would definitely say you have a bad accumulator, as most of ours are/were/will be shortly, but it sounds like the problem's deeper than that.

 

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Is this the part im looking for? http://www.priorreman.com/CatalogABS.asp??

The Prior website sucks, this is all that came up for a 89 grand prix.

 

I may try to do it myself once i can get the part. Im scared of screwing up and either my brakes going out or of damaging a $500 master cylinder. But the way you describe it, it doesnt seem to bad. Bleeding the brakes looks to be the most confusing part. Are there any special tools ill need?

 

One more question, will i need to by a accumulator as well or is that a part that comes with the master cylinder??

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I'm lucky, I found one from the yard next door for $50 pulled, I have yet to replace it though, in fact I need to get on taking mine out so I can get the motor out.

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Didn't someone here convert from PMIII to regular vacume brakes?

Many people have.

 

From what i understand this is even more difficult then replacing the PMIII. Im going to call tommorrow and order a reman unit from prior. Thats gonna be much easier then trying to track down a used unit which very well may have the same problem, or soon will.

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  • 2 weeks later...

I called Prior Reman today. Turns out they are no longer selling the Powermaster III unit. The guy told me they have no more pressure switches and cant get new ones. Nobody makes them. He told me that as long as my pressure switch is good i can send my unit in and they will rebuild it.

 

So how do i tell for sure if my switch is bad before i send the thing out? From what i understand if the switch is bad the pump will either run all the time or not run at all. Mine runs all the time once you put the fuse in, but i believe that because it is leaking fluid so fast that the pump cant get and pressure built up. Prior to the leaking i never had any problems with the pump running irregularly, at least not that i noticed. So my switch should be good then? any way to test for sure?

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Didn't someone here convert from PMIII to regular vacume brakes?

Many people have.

that's what I was going to recommend

 

Not something i would be able to do myself. And i would have a hell of a time finding someone around here to do it. No mechanics want to touch the brake system. I love this car to death, but this whole situation is really getting on my nerves.

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I coud scan in the PMIII section I copied from the 91 grand prix service manual and send it to you. It may help diagnose whats wrong.

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