| [GMCnet] Strange Oil Pressure Drop [message #271871] |
Fri, 13 February 2015 08:21  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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We sometimes forget how many lurkers we have here, and their high levels of
expertise -- I often think that the wisest among us unfortunately keep
their thoughts to themselves. This morning one of those smart lurkers
called me with a question -- probably not because I was likely to have an
answer but because I'd ask Y'All.
He, a VERY experienced and capable mechanic, just replaced his 455 cylinder
heads with freshly rebuilt ones. He changed the oil immediately after the
change, just to be sure the old oil had been contaminated with coolant.
Since he owns a garage, he used the same bulk 10W40 for both fills. We can
be sure the job was done correctly and that there was no unexpected
modification.
Before, the engine oil pressure, monitored by the OEM gauge and an
aftermarket one, ran 35-36 psi warm at road speed. Now, it's 28-29 psi.
WHY??? The push rods were replaced in their original positions. The oil
filter is the same P/N as the replaced one.
Does anyone have any clue as to why that dramatic change could have
occurred? At the current ambient temperatures, the pressure is not too
disturbing, other than the unexplained change; but, when summer comes, that
pressure is likely to drop dangerously low. We need to figure out what
happened.
Thanks for your ideas.
Ken H.
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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