low oil pressure

[matthew daley]

hi i have just rebuilt my 4.3 262 v6 chevy engine ive ran it for about 30 hrs no problem then all of a sudden oil pressure has dropped to 5 psi at idle and at 1500 rpms and above its 40 psi it isnt knocking theres no white metal in oil please help all i can think is the oil pump relief valve has stuck open any tricks to sort this out or am i goint to have to replace a brand new pump again cheers mat:facepalm::facepalm:

 

[Howard Sterndrive]

Re: low oil pressure

if those readings are from the gauge on the dash, remove sender and check pressure with mechanical pressure gauge before worrying about an actual pressure loss

 

[Levinz11]

Re: low oil pressure

5 PSI at idle is acceptable. 40 is acceptable at all other operational RPMs. A good rule of thumb is 10 PSI per 1000 RPM.

 

[matthew daley]

Re: low oil pressure

hi ive used a oil pressure tester just in case but still only 5 psi at idle before it lost pressure it was at 40 psi theres nothing in the oil so could the relief valve be jammed iff so any quick fixes like priming pump using a drill then reversing the flow?

 

[Howard Sterndrive]

Re: low oil pressure

you had 40 psi at idle? that's way too high. I think something fixed itself in your engine... or, more likely, the dash gauge was reading high for some reason before (loose connection or something).
10 psi per 1000 rpm as Levinz posted is a good rule of thumb.

 

[matthew daley]

Re: low oil pressure

ok now i ve been offerd a 1991 chevy astro van on injection can i fit my carb and other parts to this engine it has steel rockercovers iff that helps cheers mat

 

[choppywaters]

Re: low oil pressure

I would say its the sending unit. I used to work on Chevy V6's every day and that was a common problem. To be safe check the pressure with a good mechanical gauge but in my experience the sending units always went bad, very easy fix.