Hi Everyone! Glad to be here amongst all us Chevy folks! I'm Joe


I recently acquired a 1994 Chevy 1500 Ext cab 4x4 with a 350 TBI engine. The engine sounds and runs very good for what it is. At start up the oil pressure reads 40 on the dash gauge. After the engine gets to full operating temperature it drops to maybe 5 psi or less. I changed the oil and filter, I changed the electric oil pressure sending unit, and I just this weekend swapped out the sending unit for a mechanical gauge and I got the same results. 40 psi cold, low oil pressure at engine full operating temp. Could I be lucky enough to only have a bad or weak oil pump or am I looking at Bearings that are hemorrhaging oil?

 

Welcome to the forum.

I suspect your guess about the bearings is accurate. Since the pressure goes down with the engine warming up also thins the oil, that's indicative of excessive bearing clearance. You could try putting a 50 weight oil in to see if that helps the situation. For more views on this issue, you should post your question in the other section of the forum.

 

My 93 sub with 320k does the same thing at operating temp. Sometimes even triggers the check engine light momentarily at idle after a long freeway run. Only burns a qt every 1500-2000 mi and runs great otherwise. I run 10-40 vs 5-30 seems to help a bit.