lost oil pressure

[tom]

1994 D90, 3.9l v-8, 66,000 mi. I was driving the other day and lost oil pressure, no gauge, just an idiot light (I also have valve train noise now that would indicate to me no oil delivery). The first thing I did was to replace the oil pressure sending unit, same problem. I've replaced the oil pump with no avail. I didn't prime the oil pump and plan to do that next, but was wondering if anyone has had the same problem with any ideas. The possiblities I've come up with are clogged oil pump pickup, clogged oil lines into pump. I've checked the pump gears and they look to be in great shape and appear to be still driven. Any thoughts or experience is greatly welcomed. tom

 

[joey]

Sounds like sludge in the pick up tube or in the bottom of the oil pan.

 

[tom]

Yup, Joey, you are spot on... just got back from dropping the oil pan. The previous owner wasn't very good at changing oil... the bottom of the pan was filled with oil coke chips and it completely clogged the oil pickup screen. I thoroughly cleaned it and got it back together. Unfortunately, I don't have my manuals (just packed up for a cross country move, don't these things happen at the most opportune time!) and couldn't figure out how to propery prime the pump. I found a manual on line just a few minutes ago and directs that the pump be thoroughly packed with petroleum jelly... "Fit the oil pump gears so that the petroleum jelly is forced into every cavity between the teeth of the gears.
IMPORTANT: Unless the pump if fully packed with petroleum jelly it may not prime itself when the engine is started."
So, this is my next step to get it running again. Thanks for the help Joey...

 

[joey]

Maybe I am wrong, but I didn't think you had to prime the pump on the 3.9 liter... just the 3.5 liter....

 

[tom]

Got the pump all packed with petroleum jelly as directed in the manual... worked like a charm. I'm back on the road and the motor is humming right along. Thanks for your thoughts and ideas.