Hello,
This is my first posting here.
My Suburban has 140K miles. 3-weeks ago my oil pressure gauge was registering the pressure as being lower than usual. Days later the gauge plummeted and began not measuring any pressure at all. I chose to replace the sending unit, and this didn't resolve anything. I chose to go ahead and replace the oil pump, this also didn't resolve anything. I was going to go ahead and move to replacing the stepper motor behind the oil pressure gauge in the dash when I chose to go ahead and drive the vehicle while the gauge was pegged at zero.
This choice lead to the engine seizing and having to have it replaced. I've now replaced the engine with a salvaged engine. The replacement was in much better condition than my original was by looks overall and the color as I looked underneath the valve covers. It also had a compression test and came back with a 190 pounds which was pretty good.
After replacing then engine (my very first time ever doing this....and it cranked over perfectly the very first time too!!!!) the engine itself runs fine, but the oil pressure gauge is pegged at zero (still) and the sending unit is (again) brand new with this replacement engine.
Any thoughts as to how to fix this reoccurring zero oil pressure problem would be GREATLY appreciated!!! Meanwhile the truck is on blocks, and my Wife wants her truck back, just as bad as her Husband wants to be done with this 'project'.
Thank you!!

 

Put a mechanical oil pressure gauge on it to see if it is actually at zero or not. That year there was a problem with the stepper motors, so that might the cause.

 

if mechanical pressure is fine replace oil filter like a nappa gold i had it on a fram filter they stink !