i got a 95 4.3 in a s10 blazer.i just rebuilt the motor new crank new mains new rods and bearings new oil pump and everything else in this motor.now the problem i have with this thing is irregular oil pressure.i changed the sending unit and gauge but wasnt the problem.when its cold it holds 40 psi as it warms up it drops.when it hits full temp 195 the pressure is gone down to the point to where it trips the check gauge lightat 60 mph it is showing about 5 psi if lucky.it dosent knock or skip a beat in the motor so i have no idea if it even has oil flowing when it gets low psi.the motor sounds solid.if i cant figure it out it is going for sale cheap soon.so please help before i burn it.thanks alot[X(]

 

Have you put a mechanical gauge on it yet to determine exactly what the pressure is?

When you rebuilt the motor, did you set the proper clearances on the mains and rods?

 

do you have any leaks anywhere look all around underneath to see and make sure cause if you have a leak that could cause the pressure drop thats what mine is doing at the moment i have a leak i think its the rear main seal i don't know yet but thats why mine keeps dropping when at operating temp.

 

i did the mains and everything to spec.i havnt put a mechanical gauge on it yet.i checked and there is no leaks.i found something about a oil pressure relief valve any clue on where this is located i have the remote filter on this motor to.

 

oil pressure relief valve i dont know about that one have you tried a search on it i see what i can dig up and get back to you

 

allright i found this out maybe this will help its kinda long but hope it works for you, sorry everyone for the long post maybe it can be moved to a tech article somewhere by someone who knows how to set it up.hope this helps

Troubleshooting Low Oil Pressure by Larry Carley

*EDIT by swartlkk* - Linked to the article.