I am having an odd problem with my 2003 Cavalier. Following the infamous timing chain guide failure (2.2 Ecotec) and subsequent cylinder head/timing chain replacement, it ran fine for about 50 miles then the engine began squealing from under the valve cover. Turns out that following the rebuild, oil is not making it up into the journal with a filter in place and the squealing was from dry rocker arm bearings, which now need to be replaced. When I remove the filter, oil gushes into the cylinder head as it should, and a pressure gauge connected to the sending unit port reads 10 lbs (due to no back pressure). When I put the filter in, it reads 80 lbs. and no oil flows. So it seems the oil pump is working. Tried a couple different filters (AC Delco and Bosch), same result. Can't see any visible obstructions in the oil passages. Any ideas from anyone? Many thanks.

 

How did you run it without an oil filter?

 

It has a cartridge-style filter that can be removed and the cap put back on.

 

Yes, it does but I can't see running it with no oil filter. Even a cheap Fram is better then nothing.

 

Best I can say, drain oil, and with clean compressed air blow back wards from the oil passages from the heads to the oil filter.

 

Thanks, I will try that. There seems to be some kind of blockage after the sending unit port - my only thought is that somehow some kind of debris (broken timing chain guide, perhaps) made it past the pump and lodged somewhere. Seems like the pump is plenty strong at 80 PSI.

 

oilcanhenry - I agree, this was only for a few seconds with new oil to see if oil could make it up to the cylinder head with no obstruction. It flows up freely and seems to bathe the cams but does not gush or overflow the cylinder head.

 

Well, if you're unable to find the obstruction, until the seventies almost every motorcycle ran without a filter (just a screen) and they did just fine. On my old bikes I install magnetic drain plugs.... I wouldn't worry about running my Cav w/o a filter.

 

That's a great suggestion, thank you. I could probably fashion a screen to fit in the filter cavity that would catch anything big and would still not impede the flow too much. That plus a magnet in the oil pan. Unless I clear the obstruction, the car is headed to the junkyard anyway.

 

Tried the compressed air thing yesterday, There doesn't seem to be an obstruction between the filter cavity and the head. At the bottom of the filter cavity where the oil comes up through the center of the filter cartridge there are two holes, one round and the other C-shaped. The round hole seems to be a separate path to the oil pump from the C-shaped hole, as when I shot air into the round hole it seemed to flow unobstructed. The C-shaped hole was much harder to get air into - I stuffed a foam pad into most of it and tried to keep just a small hole for the tip of my air jet, but I couldn't really seem to get air to go in, it kept wanting to com right back out. It's as if the C-hole path is obstructed but the round hole is not - which make sense given that with no filter in place the oil flows freely - there is a round tip on the oil filter cartridge that fits into the round hole, and it has an o-ring on it to seal. If that is the only path for the oil I can see why it works without a filter but not with one. I did some homework on the oil pump and learned it's actually in the engine front cover, which was on and off several times during the whole cylinder head repair saga. I suppose it's possible something happened during those repairs because the pump exit port was exposed.

Does anyone know about the oil routes from the pump to the filter? is the C-shaped path separate from the round hole path? If that's the case I could try modifying a filter by removing that tip - it would still stay relatively centered and might work better than nothing. Thanks for any information.