Powermaster pump motor?

[douglas james]

Ken and others - 4 related questions

When I turn my key on (engine off) the brake pump motor turns on and makes a hell of a racket. It is getting louder and louder as time goes on. It stays running for about 10 seconds and then turns off. Also, whenever I push the brake pedal, the pump motor also comes on for a few seconds. There are no visible leaks in the system, no warning light, no hard pedal, no soft pedal, fluid level is fine, the car stops fine.

When I de-pressurize the system and then turn the ignition on (engine off) the pump motor runs for about 25 seconds. This leads me to believe that I need a new pump motor ) as opposed to an accumulator, but I am hesitant to buy something based on my diagonosis. Poston and Kirban tell me I can only buy the entire powermaster system ($400 - $500) and not just the E-H pump/motor (about $160).

Sooooo - I am going to take it to technician who probably hasn't a clue as to the sequence of steps that should be take in determining the problem. Hence, question 1, do you have any suggested step-by-step procedure that the technician should followin identifying and solving the problem. I have your parts and wiring diagram for the powermaster.

Question 2, if it is the pump motor, do you have steps to be followed in replacing it?

Question 3, should I also purchase a pressure switch if it is the pump motor?

And finally, question 4, where can I purchase the pump motor and the switch if the pump motor is the problem.

Thanks, and Merry Christmas. You do a lot for us Buick neophytes and thanks for being there.

Doug

[Keller]

- The pump motor should run at key on. Longer if its been depressurized before key on. If you are getting a loud squeal or other nasty noise, it may be time for replacement.

- Check the test sequence to determine if what you've observed is within spec or not. If its not hard linked in this thread, then its on the website in the Brakes tech area. Straight out of the factory manual. Not sure what you need a 'technician' for or why you would trust them.

- E/H motors were being manufactured by Maval Gear, Twinsburgh, OH. They are able to be obtained straight from Hank Terry and manufatured by them. The motor is very straightforward to replace, as there is little holding it in. Just depressurize the system, disconnect, and replace. Look in our Vendors section under "Power Master Motor/Pump Sales".

- The pressure switch is not obtainable from GM. Not sure that the rebuild companies are using new ones. If your pump motor is making noises, the switch will not make it make those noises.

[chrisgarrett]

http://www.members.tripod.com/Turbocars/pm.html