| [GMCnet] Hibernating for way too long! [message #357690] |
Thu, 13 August 2020 10:39  |
Greg Jankowski
Messages: 2
Registered: August 2020
Karma: 0
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Junior Member |
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Greetings, I'm a lurker coming out from under the trees (with pine sap to
show for it).
A major brake job has stalled out for over a decade due to my inability to
bleed rear brakes. The culprit seems to be the master cylinder(s) (new P30
Napa NMC M2219) The front discs bleeds beautify, the rear brake side
refuses to have enough pressure/flow to purge the air. I've purchased 3
master cyls so far & have tried bleeding them;
1st mounted, 2nd bench bled, 3rd pressure bled bench. All with the same
results, the front cylinder/rear brakes never get enough pressure to push
my finger off of the outlet.
Complicating the project is the scope of the project so far it has entailed
the following parts; rotors, pads, larger rear wheel cylinders, SS rear
hoses, brake shoes, all the brake lines and the 3 masters. Thanking you in
advance.
Greg Jankowski
Wheat Ridge, CO
73 23 CanyonLands
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| Re: [GMCnet] Hibernating for way too long! [message #357698 is a reply to message #357690] |
Thu, 13 August 2020 16:21  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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About 7 or 8yrs ago, after installing a disc system on the mid axle, I was convinced that I needed a P30 for the extra volume. I ordered one, and could not bleed the front part of the MC...just would not make pressure. I got 4 more of those, one after the other that would not bench bleed. On the last one, I fashioned a levered system and was finally able to break the front piston loose from the bore. But then it leaked. Each one of the MC's that I got (total of 5) had to be brought in from another store in their system. Each one of them had been sitting on the shelf for many years. That P30 is no longer a hot item, so they were drawing from P30's that had been shelved for many years, and I am speculating that moisture had corroded that front piston so it would not break loose on a bench bleed. After that experience (that BTW, I was doing out in the snow) I finally borrowed a stock MC from a friend. Drove it for several thousand miles with no issues and a solid pedal. There are other issues with the P30 that Dave L explained and demonstrated to us in one of his GMCMI sessions that could lead to near complete failure of the P30. If I were you, take the MC back in favor of the stock MC. You may have to get it from Jimmy K at Applied, because they are hard to find through normal parts house channels. JMHO
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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