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Yes, you are taking the pressure reading right off the pump. But thats the same as putting a tee in your garden hose. You're reading off the tee. If you let water run out of the end the pressure at the tee goes low. If you pinch the end off you get pressure at the tee.
All of the bearings are the pinched off end of the garden hose. The more bearing clearance the less it's pinched off and the lower the pressure at the tee.
Pressure is the resistance to flow. Read the oil pressure as you did and get 10 psi, then take the oil filter off (opening the system and eliminating resistance) you're going to read zero at that gauge.
I am aware that publications say 10 psi per 1000 rpm so 6 psi at idle is "normal" That's pure BS.
Everything I've ever seen with less than 18 psi oil pressure at idle and less than 40 psi max hot has had a mechanical problem.
Your pickup screen is not plugged (unless someone dropped the oil bottle seal in the engine and it somehow made it's way to the pan)
What is the pickup screen going to be plugged with at 76,000 miles?
Oil filter bypass stuck open? It's going to bypass the oil filter, if anything that will raise the pressure.
And whatever you do please don't take it out and replace it or send it out for a rebuild. Find the problem, then have it fixed. This is how we all learn.
Thanks for the response. Even though it may take me a few months to complete, I have decided to keep the car and fix the engine. At first, I was hoping it was the common issue with the sump o-ring failure. Now that has been eliminated. It has a brand new Melling oil pump, so the chances that both my OEM pump and new pump have bad bypass valves is almost zero, so that is eliminated. The engine has no knock or detectible metal shavings in the oil. From my research, a cam bearing may have moved out of position causing an open flow in the engine. Checking the cam bearings, I believe, is something I can do without an engine pull. I will pull the cam and visually inspect the bearings. When I complete that inspection, I will decide the next direction. The fun continues…please keep the advice coming. I have very little experience inside an LS and only modest inside other models.
I am slowly breaking it back down to check the sump screen for blockage, the cam bearings for walking, or the general clearances of the crank and rod bearings.
Working a couple of jobs and life have it going at a snails pace. Had to pull off to do a brake job on my wife’s Beetle then change diff oil in my son’s Silverado.
Got the vette up on jackstands, swaybar/steering rack out, and will be pulling the balancer and front cover off this weekend.
The engine cradle must be dropped to make my checks. Not technically difficult, but lots of labor.
My plan is to drop the oil pan, pull the sump to inspect and look for blockage or split seams. If no problem is seen, I will drop shield under the crank and visually inspect the cam bearings for walkout. If I can’t find any obvious problems causing my low oil pressure, I guess I will pull the engine and plan to replace all the bearings? I may get done by the end of 2023!!!
02-21-2023, 12:48 PM
