Bought a 1998 2500 with 77,000 miles on it. Oil pressure would follow engine RPM about 10 at idle and go toabout 30 atcruise.While driving it home stoppedfor gas(300 miles) and when I started it up,a lot of clattering went on in the engine compartment. Shut it down, checked the oil and it was good. Waited a while and started it up again. The lifter noise (I think) calmed down and I took it to a friends house. Nextdaytalked with a mechanic and he said theoil pump is going bad and has been for some time. Heput 20-50Woil and a quart of Lucas oil in it to get me home to FL (500 miles). Oil pressure went up to about 45 and stayed at cruisebt would drop down to about 10 at idle. With the radio off, I could hear what sounded likelifter noise when I was going down a slight gradepressing the gas a little tokeep up speed.Going uphill it wouldn't clatter.

Anyway, I'm sure the oil pump is bad but would like to know if it can be changed without raising the engine and what is the possibility of the lifters surviving the ordeal. When I start it in the morning it takes about 15 secondsto idle correctly and I don't know whether it is because the lifter aren't pumpedup or what.Has some kind of tapping sound asRPM goes up whilein park -maybe a weak lifter????

Bob

 

You can change the oil pump with out pulling the motor. There is actually a lot of room under there to work. Before you change the pump I would do a block flush first. Don't go cheap here use quality parts and gaskets and use synthetic oil. I would do all that first before you cheek lifters it could be just not getting enough oil. But if it still makes the noise I would start fixing the top half.

 

Thanks - I'll try the flush first and go from there. The pressure was very low at idle and would only move upa bit at cruise - hopefully the flush and pump do it. Checked with Advance auto - the pan gasket costs $33 and the pump $19 - sounds strange to me but what the heck...

Bob

 

I went through this about a month ago. Luckily I caught it right away. My motor has about the same mileage as yours. What I found when I dropped the pan is the pickup was full of crap. Even though I still replaced the pump with a Melling High Volume. Put it all back together and I am back up to 40psi where it was back in the day.

 

Just bought a durango with a 360. Previous owner just had this done before I bought it. Did a oil pump and flush. Been driving it for three months now and seems to have great oil pressure. Pull the pan and clean everything out,might as well put a pump in while it's apart. Pumps are cheap.