Hi, Took my Desoto for a spinn yesterday and noticed that the oil pressure drops when I accelerate or rev the engine (even when Im standing still). The engine is an old 265 flathead 6 with unknown mileage. The oil level is ok. At this point I basicly have three theories why it drops. 1. Bad bearings. The bearings are worn and loose pressure when the RPM rises. 2. Bad oil pump. When the RPMS increases the pump cant maintain pressure. 3. Faulty oil pressure relief valve. When I bought the car the valve was missing (only had the spring and not the actual valve). So I made one which I basicly guessed how it should look like. Also worth mentioning is that when the engine is cold the pressure is zero and it takes 10-15 minutes for it to begin rising as the engine heats up. Any ideas how to attack this problem? /Daniel
The first thing I would do, if it hasn't been done already, is put a good mechanical gauge on and see what that tells you. I would also call the home made valve into question, not criticizing your abilities. Do the bearings make any noise at startup or when not under a load?
The engine is silent and dont give any bad noises at all. So there is oil flow in the system. Regarding the valve its basicly a make do solution since its hard to find any replacements in Sweden. When I run it without the valve the pressure is more or less zero at all times. Since this problem occurred Im a bit unsure about its exact function right know.
It sounds like a guage problem. If it had no oil pressure,it should rattle bad till the oil pressure comes up
Could the motor be all sludged up on the inside causing the oil to not return to the pan fast enough. Pop the valve cover and take a look.
Maybe the intake screen is plugged and won't supply the volume of oil when it's revved up. No oil pressure at start-up is scary too.
http://www.jalopyjournal.com/forum/showthread.php?t=743060 Happened to me aswell. I found a loose pickup
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