2004-4x4 130k changed lower intake gasket, flushed crankcase, after 3 weeks oil pressure dops to 0 at idle after warm up. Changed pressure switch. same thing. Changed filter only, oil looks good. Question, could the remote filter lines be clogged? Should I try another flush?

 

Clogged oil cooler lines would cause a pressure build up in the lines, and the rubber portion would most likely burst. Is the engine knocking? Could be a clogged oil pump pickup screen, a bypass valve stuck open, (aka regulating valve in the engine block) or worn main or rod bearings. This diagram illustrates how a regulating valve being stuck open could cause the problem. It's fairly common on 4.3's and it will cause oil pressure to drop to zero at idle if it's stuck open, or if the spring is weak or broken, (the majority of oil pressure is directed back to the oil pan).

 

Is the pressure valve easy to replace?

 

The valve is located above the oil filter adapter on the left rear corner of the engine. The oil cooler line connection must be removed from the adapter, (one bolt). The adapter is then removed from the engine block, (two bolts) exposing the valve. It is "press fit" into the block, and can be difficult to remove. It pulls straight down, (not threaded). The new valve is pressed in until it is flush with the block.

You will need these gaskets:

http://shop.advanceautoparts.com/p/f...erm=oil+cooler

http://shop.advanceautoparts.com/p/d...6201&showTitle=

 

I have never heard of this. Thanks for the info and the diagrams. Is the cooler line, the one that goes to the filter? I'm assuming I can use a socket to press the new one in.

 

Yes, it's where the cooler line attaches to the engine.... neatly tucked out of the way A socket would work well to install the new valve, and a slide hammer works well to remove the old one.

 

I cant add to your rep enough, not as much as I would like to. You are too smart for your own good on these monsters LOL

 

Thanks Richard, you can't buy experience, it can only be earned I take some pretty good pictures, but I'll never be half the photographer that you are. I've seen some of your work.... it is amazing!

 

Man, I wish I had known about this when I went through and fixed all the remote oil line stuff last year! Lately I've noticed my oil pressure gauge has been kinda twitchy every now and then. I'm hoping it's just the pressure sensor, because I REALLY don't want to have to get back in that remote filter adapter!


Oh, and...
Can't agree more with this!

 

this is a rare part GM parts guy for twenty years has never heard of it. But "There it is" was his responce when he looked it up. "There is one in Van Wert, Ohio." Did another flush, still a lot of sludge comming out, did seem to help.