This is driving me crazy, Motor has 94,000 miles. Dash gave me the low oil pressure signal, hooked up mechanical gauge to confirm low oil pressure.


Here is what happens, Start engine good oil pressure 40-50 psi then it has a rapid drop to ZERO pressure once the engine rpm is increased to simulate highway driving.


Replaced oil pump and pick up tube. Start engine great pressure 50+ psi but once the engine warms up the oil pressure under increased rpm drops very rapid down to ZERO. I can shut the engine off and instantly restart engine (within a few second window) and the oil pressure will resume to normal 40psi.


I don't think the oil return ports could be plugged because on a rapid restart the pressure is there, I don't think cam or main bearing could be bad for the same reason. I can let the engine idle for an hour and have great oil pressure. Please help


Signed,
Oilless in Michigan

 

I'll assume you cleaned the bottom of the oil pan when you had it down and blockage of the pickup tube is not the issue. With that out of the way my next suggestion would be an overly clogged oil filter. You run the engine and the debris clogs the filter, turn it off and the debris falls away. This cycle would give you the high initial pressure and the falling off of pressure.

 

I forgot to mention, replaced the oil pan due to extensive rust on the exterior. Replaced the oil and filter with 10w-30 oil and new Fram oil filter. Pickup tube was clean when reinstalled.

 

Well regardless, you're dealing with a clog in the oil system between the pump and the oil pressure port. Have you tried giving it a good run with a quart of motor flush in it?

 

I thought about the clog you mention and I pulled off the new oil filter, cut it open and it was packed with sludge. I put new oil in and new filter and flushed the engine. Pulled the filter and cut it off still had some so I repeated the process again until the filter was clean. I just bought this van last week, glad I didn't pay but a few hundred for it. Tomorrow I'll change the oil and filter again and give it a go and see how it does. Thanks for the tip off. I'll report back

 

Ugh, good thing you went so far as to open the filter and look. With the filter clogged up like that it means most of the oil was passing through the bypass valve and going into the engine unfiltered.

 

is it getting better since you have been flushing it?

 

Did you use a pile of RTV sealant? I've seen that plug oil pickups after it squishes out from around the oil pan.
Steve

 

Well I drained the oil this morning ( had the motor flush in it) and it was LOADED with sludge particles. I removed the pan and I was astounded at how much sludge was in the bottom on the brand new pan. Cleaned it out, replaced the gasket, filled with new oil and new oil filter. Test drove the van 10 miles and never once did the oil pressure drop below 40psi with the mechanical gauge. Brought it home installed new oil pressure sensor and put the dog house on and test drove van again. Same results with the oil pressure.


Thanks for making me think about the clogged ports. My second time doing the oil pan R/R I was able to complete the job from start to finish in just under 1.5 hours. Not sure if I should be proud of that or not.....LOL

 

Good job, glad it didn't turn out to be a major engine repair.