|
My 2 cents. A lot of discussion on this lately, and most of it basically says “as long as you have some oil pressure, don’t worry until it’s time for a rebuild.” I disagree. I have a “B” an “M” and a 51 GMC truck that all at one time had low oil pressure at warm idle. I did not think it serious as they still had some pressure so kept running them. In EVERY ONE there was a problem. The “B” had a warped plate and blown gasket on the oil pump, the “M” had crankshaft bearings “flaking” (I found a few when I changed oil) and the GMC had anti-freeze leaking into the crankcase. When these engines finally came down, the “B” needed the crank ground “0.020”, the “M” “0.030” and the GMC crank was shot (the M and the GMC both eventually spun a rod bearing). My opinion is that unless you have a “dipper” oiling system, if you have idle oil pressure at less than ¼ of the gauge or 15#, the engine has a problem. I would drain the oil and check for flakes in or around the drain plug. If you find some you know what is going on. If not, consider taking the pan down and plasti-gauging the bearings. At least then you will know if the bearings are just worn a bit or if you have real trouble brewing in the engine. I just tore apart a 351 V-6 that had a light “knock” at high idle, but “reasonable” oil pressure. The number 6 rod bearing and back main are almost “hammered” out totally, and the rest have light scratches. Thanks to the quick tear down we will be able to salvage the crank and rods. (The engine had 250,000 miles on it.)
| 
