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Oil Pressure Drop; 10.13 Oil Pump
Topic Started: Feb 8 2009, 05:32 PM (514 Views)
Duane
Member
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I have a very recent re-build on my F-head. oil pressure was initially fine. It started to drop the other day when it was run on the road for awhile. It dropped to almost zero. When warming up the oil pressure was great. After running for 10-15 miles the oil pressure starts to drop. Tthe oil pressure guage has been tested with another guage and it checks out. It is concerning to see the guage drop. I have trailered it home. Any ideas? The engine has a new pump.
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oldtime
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MODERATOR
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Considering there are no apparent oil leaks one factor that effects oil pressure is the relative fit of the engine bearings.
Loosely fitted main bearings and or connecting rod bearings will cause the pressure to drop.
Another factor is the oil pump itself including either the impeller tolerance or the oil relief spring.
Perhaps the oil relief spring stretches when the engine warms.
I usually re-use original old oil pumps. They last a long long time.
Original pumps are much better quality than some of the aluminum body repro pumps I have seen.
One last concern is that you may be loosing oil pressure up at the rocker area.
Currently building my final F-134 powered 3B .
Rock Crawler using factory parts from the Willys Motors era (1953-1963)

http://s4.zetaboards.com/CJ3B_Bulletin_Board/topic/30228766/1/#new
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elawson
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Excess clearance between the cam bearing surface and the bore can cause an oil pressure reduction as the engine warms up.



Does the oil smell like gasoline? A leaking fuel pump can mix gas into the oil and cause a lot of problems.


Eric
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