Powermaster issue

[Joe DiMura]

Just a little background. I haven't driven this car much in many years but prior to that I replaced the PM pump and accumulator. I've have been driving the car some and started to notice the PM pump sometimes won't stop running after 12 sec like it should. I changed the pressure switch b/c it was easy but it's still not stopping at times. There are no noticeable fluid leaks anywhere, either on or around the pump or at the brake lines or brakes themselves.

any ideas on what I can do to figure out what's going on.

 

[Anthony P]

Hi Joe, I'll scan and upload the powermaster section from the Service manual tomorrow morning.

there is a sequence test to do if the pump does not shut off in 20 seconds. there may be backflow into the fluid reservoir rear port which would require the replacement of the power piston.

test #2 is checking pump pressures. For this test and maybe the power piston stuff, I might consider sending the PM unit to Richard Clark's Garage and let them go thru it and service it.

there is also a flow chart for troubleshooting. I'll find that as well. should have that for tomorrow as well.

 

[Joe DiMura]

cool thanks!

 

[Anthony P]

attached are the service manual pages and the flowchart. functional check/test begins on page 8.

Mr. Clark & Co. put together an o-ring kit to service the powermaster. I think that kit can be purchased through both RCG and Kirban's. If it's coming out, might as well go through it. I would not trade in your powermaster since you noted it has a new pump and accumulator - that is why I'm suggesting the servicing route.

Don't know what test equipment/setup you have in your garage, but I know there is basically a plug-and-play PowerMaster benchtop test rig at RCG. Just keep that in mind as you troubleshoot. So much of the testing procedure requires the use of a gauge tee plus a good gauge at the brake switch to measure the pressure at each step. Trying to suggest working smarter and not harder if you do not have test equipment once you've looked at a few things.

 

[Joe DiMura]

Anthony thanks for uploading these for me. I'll read through them and see if I can complete the steps here myself. I've got access to auto tools including good gauges from a good buddy who owns a repair garage, so I'll take it from there.