1995 Ford F-150 oil pressure problem

METZMAN665

MEMBER
1995 FORD F-150
V8
4WD
AUTOMATIC
75,000 MILES

I gave my 95 f-150 an oil change and the oil was very black. After the oil change the oil pressure was good and no knocking noise until the engine warmed up, once the engine is warmed up oil pressure drops to 0 and the engine rattles. If you press on the gas the nocking noise goes down and oil pressure goes up. I changed the oil a second time and same thing occurs. The auto shop suggest replacing the entire motor. My father-in-law suggest replacing the oil pump and adding oil additives. The engine starts just fine on the subsequent start ups. Do you suggest replacing the engine or just the oil pump?

1 Reply

PEAR69

MECHANIC
1,482 POSTS

Well first of all i'm going to be honest with you. When an engine runs with no oil pressure severe damage occurs in a matter of seconds. The bearings in a motor need an oil wedge between them and the steel of the crank shaft. When your motor ran with no oil pressure that wedge was gone. This obviously wears out the bearings. The bearings in your motor undoughtingly have more than normal wear on them because of this. The knocking you hear is most likely the bearings. It doesn't matter now if you change the pump or not. The bearings are still going to knock, and knocking bearings will eventually knock themselves right out of your engine. Most likely through the side of the block.
If you can live with this inevitable fate then just replace the pump and run her till she blows. Be sure to put a regular stock pump in it. A high volume pump is never necessary in a stock motor even when the bearings and such are perfect. Good luck