Reader Question I have a 1985 Ford F250 4×4. everything seems to be fine except the oil pressure. the pressure is fine when i first start it up and for awhile after. when the engine starts to warm up thats when the pressure gauge goes down. i checked the oil when the engine was running and when it wasn’t(hot and cold) and the oil level seems to be fine.
It only starts to happen when the engine temp. gets about a 1/4 way on the gauge. then the oil gauge starts to go down and then it will go back. so basically it goes up and down. is that normal? I’m not really use to the truck since i just got it, it was my step dad’s and i got it when he past away so I can’t ask him. I know he kept it running good and everything. please help me out.
As the engine heats up, so does the engine oil and when the oil is hot it will actually get thinner…and is probably what you notice on the gauge. What you should be concerned with is what is actually happening at the oil pump itself, and using a manual pressure gauge you can check the oil pump pressure to make sure the pump is doing its job.
If you don’t hear any “clacking” engine noise (due to low oil pressure from a weak oil pump) and you just want to take a GUESS at something…I would buy and replace the engine oil pressure sending unit. Get one from your local auto parts store and just unscrew the old one and install the new one.
In most cases, erratic oil pressure gauge problems are the cause of a bad sending unit. It’s a cheap guess, and easy to replace. If you still have the problem…then it would be time to manually check the oil pump pressure and test the dash gauge itself.
Using thicker weight oil, like straight Castrol 50 weight will also help boost oil pressure on an engine with some internal wear and tear.