Author Topic: Powermaster short cycling  (Read 9732 times)

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Offline daveismissing

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Powermaster short cycling
« on: July 24 2011, 01:46:45 PM »
PM has started to cycle ~15 seconds.
Doing this even without brakes applied.

It will pump up from depleted ~12 seconds so that seems OK.

I'm thinking internal leaking in Master cylinder?

Maybe check valve in pump/motor leaks?
Where is that thing anyways?

Suggestions to narrow it down further?
-Drain plug by Earl Brown, custom oil pan by Rich's Auto

Offline Pyro6

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Re: Powermaster short cycling
« Reply #1 on: July 24 2011, 03:29:15 PM »
I'm thinking that's on the power assist side. If you're not on the brakes, wouldn't think the master cyl. bypassing. Accumualator maybe?

Offline daveismissing

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Re: Powermaster short cycling
« Reply #2 on: July 24 2011, 04:06:50 PM »
-Drain plug by Earl Brown, custom oil pan by Rich's Auto

Offline daveismissing

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Re: Powermaster short cycling
« Reply #3 on: July 24 2011, 05:25:12 PM »
Interesting:
http://www.turbobuicks.com/forums/buick-v6-turbo-tech/91871-power-master-check-valve.html

A picture of a spare PM. Where is the checkvalve,
is it under visible mating surface- if so how would you get it out?
or am I missing some bits?

-Drain plug by Earl Brown, custom oil pan by Rich's Auto

Offline Pyro6

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Re: Powermaster short cycling
« Reply #4 on: July 25 2011, 05:22:16 PM »
Is it still mounted on the steel line?

Offline Turbodave

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Re: Powermaster short cycling
« Reply #5 on: July 27 2011, 01:11:38 PM »
Interesting:
http://www.turbobuicks.com/forums/buick-v6-turbo-tech/91871-power-master-check-valve.html

A picture of a spare PM. Where is the checkvalve,
is it under visible mating surface- if so how would you get it out?
or am I missing some bits?



That part you're showing needs to be pulled out. The check valve and spring are behind it.
TurboDave EWCS(SW) USN (Ret.)
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Offline Turbodave

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Re: Powermaster short cycling
« Reply #6 on: July 27 2011, 01:13:54 PM »
Something like an easy out down in the center and trying to pull/twist it out.
TurboDave EWCS(SW) USN (Ret.)
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86 GN(Translator Pro/Extender Pro/w Boost control, PLX WBO2 (original owner)

Offline Turbodave

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Re: Powermaster short cycling
« Reply #7 on: July 27 2011, 01:17:55 PM »
Part numbers 36/37/38
TurboDave EWCS(SW) USN (Ret.)
Sevierville, TN
Translator Pro;  MAFless fuel, spark, boost and fuel pump management

86 GN(Translator Pro/Extender Pro/w Boost control, PLX WBO2 (original owner)

Offline daveismissing

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Re: Powermaster short cycling
« Reply #8 on: July 27 2011, 07:07:53 PM »
Thanks for the link

Something like an easy out down in the center and trying to pull/twist it out.

Won't that damage the poppet below?
Interesting that guys say their flew out and apart, not this one.
I made a "spring hook" from a paper clip- it just unbent without budging.
-Drain plug by Earl Brown, custom oil pan by Rich's Auto

Offline Turbodave

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Re: Powermaster short cycling
« Reply #9 on: July 28 2011, 06:44:18 AM »
I personally haven't pulled one out, but I've seen it done many times at Richard Clark's place.  NONE just flew out!!  They all had to be pulled.
TurboDave EWCS(SW) USN (Ret.)
Sevierville, TN
Translator Pro;  MAFless fuel, spark, boost and fuel pump management

86 GN(Translator Pro/Extender Pro/w Boost control, PLX WBO2 (original owner)

Offline Turbodave

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Re: Powermaster short cycling
« Reply #10 on: July 28 2011, 10:37:48 AM »
I just went down and pulled one out of a spare mc that I have.
 
It's not easy but can be done.  What makes it so difficult is that it's held in place with an O ring.
The tools I used:  I have a set of Craftsman torx drivers, the ones that have screwdriver type handles.  The torx end of a T10 will fit down inside that hole in the center, and as the trox fins go up the shaft they spread out wider.  This makes it easy to stick it down in there and while pushing down I was able to turn that part of the check valve assembly to sorta loosen it up.
Then used a sort of pick device with a bent end to go down inside and pull it up out. Broke the tip off the pick but what was left was stronger, and was able to pull the valve up out.
 
Once thats up out of the way the small flat disc down inside can be pulled up out with a magnetic probe and will bring the spring with it.
TurboDave EWCS(SW) USN (Ret.)
Sevierville, TN
Translator Pro;  MAFless fuel, spark, boost and fuel pump management

86 GN(Translator Pro/Extender Pro/w Boost control, PLX WBO2 (original owner)

Offline SuperSix

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Re: Powermaster short cycling
« Reply #11 on: July 28 2011, 12:00:13 PM »
Cool Dave - you are the man..  :icon_super:
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Offline daveismissing

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Re: Powermaster short cycling
« Reply #12 on: August 10 2011, 12:21:57 AM »
Not much time to get to this-
I had one of Kirban's new humongous accumulators on order.
Installed and of course being a larger "spring" it stretched out the cycles to more like minute.
Pushed it out of the zone where I figured the motor was going to burn up at least.

Was intrigued by the external checkvalve idea so pulled out my Mcmaster Carr and found
a 1000PSI chemical resistant valve and made up some adapters to insert between
the pump and MC. Certainly behaved differently but the cycles ultimately continued,
I figure the Master Cylinder must be leaking down internally.
Sigh....
 

-Drain plug by Earl Brown, custom oil pan by Rich's Auto

Offline Pyro6

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Re: Powermaster short cycling
« Reply #13 on: August 10 2011, 12:25:56 AM »
You know, even though I think my MC is toast, my PM doesn't cycle.

Offline daveismissing

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Re: Powermaster short cycling
« Reply #14 on: August 10 2011, 12:29:52 AM »
Yah,... I suppose it's the least dramatic form of failure at least   :O
-Drain plug by Earl Brown, custom oil pan by Rich's Auto

 

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