Oil Pressure Problem

plumber · February 25, 2006

We have a '97 Suburban w/5.7L and 120K miles. A couple of weeks ago, my wife called to say the truck has an oil leak. I found the gasket for the oil filter "blown out" on one side. I replaced the oil filter and replaced the 10W-30 oil that leaked out. Upon start-up, I noticed that the oil pressure gauge was reading much higher, but the problem seemed to be fixed.

Today, my wife had the same thing happen to her again. I found the same problem...the oil filter gasket was blown out partially, so I again replaced the filter and the oil. I started the vehicle again and almost immediately, the gasket blew out again. Filter was adequately tight, by the way.

I have been using 10W-30 oil and the outside temp is approx. 25-30 degrees. The truck has a factory oil cooler. Two thoughts that I have had so far:

1. The rubber portion of the oil cooler line has a problem causing a restriction in the line, resulting in excessive oil pressure and this in turn causes the oil filter gasket to "pop". But I also believe the oil pressure relief valve should open up to reduce excessive oil pressure should it occur. But if my thoughts about the relief valve are correct, then #1 shouldn't happen.

2. The oil pressure relief valve itself is sticking (not opening up) and the excessive oil pressure from the cold oil is not being by-passed.

One other fact worth mentioning is that the motor does have a tick or "knock" (I hate to use that word!) when cold, but definately goes away when warm.

I plan on removing the oil cooler/filter adapter and just use a standard Chevy oil filter adapter that I have lying around, to see what happens, but I am looking for other suggestions. How do the oil cooler lines disconnect from the adapter as they do not look like they have the standard plastic clips that pressed together in order to pull out the steel line from the housing??? Please help as the truck is obviously "down" and can't be driven. Any input would be much appreciated!!! Sorry for the long post.

plumber · February 25, 2006

Update: I bolted on a standard oil filter adapter and PF-25 A/C oil filter (eliminated the oil cooler) and basically the same thing happened. It popped a portion of the oil filter gasket to one side and started leaking.

My next thought is the oil pump relief valve that is part of the oil pump is stuck to the point that it will not open up causing the oil pressre to go sky-high. Is it feasible to have this happen??? If so, is it possible to remove the oil pan with the motor still in the vehicle? It is a 1500 series Suburban with 4-WD. Any help would be appreciated!!

GM-Tech · February 25, 2006

Is it feasible to have this happen???

That's about the only thing it could be. We've seen this before. In fact, we had quite a problem on the Quad-4 with sticking pressure relief valves. The pressure would go so high on startup (120-130 psi) it'd pump up the lifters, hold the valves open and it wouldn't stay running.

plumber · February 26, 2006

Thanks for your response. Is it possible to "clean" the oil pump and free up the stuck relief valve and re-use the pump? Will the pan come off without having to lift the motor??? It's 4WD & a 1/2 ton series Suburban - 1997.