Yes yes, I know the search function, but I am having issues that I haven't been able to solve yet, so here is yet another oil pressure thread. Picked up a 2000 4.7 AWD with 139k on the clock. Bought at an auction, so I have NO idea on maint history.

Fresh synth oil/filter change, Castrol 5w30. I did this before I drove it home.

The issue - During warm-up, no issues, runs great. After everything is heated up, oil pressure drops at stops/idling. Only if rpms fall below 1k. Oil pressure (as indicated on factory cluster) stays just to the left of '40' as long as a little bit of throttle is applied, enough to keep the engine above 1k.

I understand a mechanical gauge is in my future, but has anyone had a similar issue? Any other ideas on where to start looking. Thanks in advance for your time, and thanks for a great community!

 

Welcome to DF
Checking the oil pressure with a gauge is a good start. It may end up being an oil pump?

 

Thanks. I was thinking the same, however I don't know why it would be so dependent on rpms. I'm not driving it yet, just trying to get it right before I do. What are the group thoughts on oil pickup blockage? Are my symptoms similar to anyone that has had that issue?

 

I had the same issue on a Grand Prix once - it was much older, perhaps a 1978.

In the case of that car, the oil pressure would move like the tachometer would and in that case it was a blown head gasket.

Hope it's something easy for you - I'm not sure if these D's have a feeder tube in the oil pan (luckily, I haven't had to mess with the oil pan at all on this), but that's another possibility too - I would definitely check that, since it's usually just a good cleaning and you're done. I had a LeBaron once that was clogged so bad the oil pressure totally dropped out to where I couldn't drive it. After dropping the oil pan and taking 10 minutes to clean the pickup tube good, it was never a problem again.

Just might be something else to check on, if you can't find anything else.

 

as long as the oil pressure is staying between the two has marks on the dash you are fine




this picture of my dashboard is at idle before it was fully warmed up, when idling at around 500rpm the oil pressure will usually sit right on the left hash mark, or just slightly above it (not on the pin, its the middle hash marks which matter, or the 'safe' zone)

a picture of where it is going would be helpful

 

I will take a photo next time I run it, but the pressure drops to 0. As in, where the needle sits when they key is off. I picked up a new PCV and oil pressure sender, no changes. Still looks fine on start-up, then drops off below 1k rpm. Did put 100 highway miles on the new oil change, pressure stayed up as long as rpms were above 1000, no weird noises or knocking etc and etc. this is weird. I'm thinking next step is dropping the pan?? Anyone have anything else to check? Thanks for the responses everyone!

 

I'll do you one better, here is a video of my symptoms. http://www.youtube.com/watch?v=z5t4zesctLA

 

That's what I would do too - check that pickup tube. Might just be that it's clogged enough that the oil pump can't grab much at low RPM, when it spins up some, it can manage to pull oil in past the gunk.

Plus - other than a new pan gasket and such it's pretty much a 'freebie' repair option and never hurts to check to see if it's clean, considering the importance of oil in the engine...

 

soundsl ike the oil pump is on its way out unfortunately

 

Ok, sounds like I'm not thinking crazy then. I'm stationed at Benning, so I will head to the "auto skills center" to use their lift and a proper gauge this weekend. I assume I have the mechanical skills to drop the pan and check around but the oil pump replacement looks like a hell of a job. Any thoughts on what a good price to have that done would be?