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Ford truck f150 with 351 w modified engine

(1990 Ford F-150)
in Orangeburg, SC on May 20, 2010
when the engine is cold the oil pressure is 65 to 70 psi. as the engine warms up the pressure slowly drops off to 10 to 12 psi. as the engine rpm's are increased to 1000 1500 the pressure will increase to 35 - 40 psi. the oil is clear and the engine runs smoothly. is not smokeing. maybe oil pump wear problem?
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Popular Answer
on May 20, 2010
If this engine has been rebuilt and the builder changed the oil pump they might have installed a high volume pump and these pumps will drop pressure when hot because the oil gets thin. I always go for the high pressure pumps if I can find one when building our muscle cars because nothing is more irritating than having a new engine with low pressure when its hot and as long as its not below 10 psi it should be fine
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on July 11, 2010
Hemicuda is right..this is a problem with street engines. A weak bypass spring can do this also. First though, change the oil and filter. If there is water in the oil it can restrict the filter media as well as dirt(water expands paper media) and also check to see if you are using a high grade and proper viscosity oil...good luck:)
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