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L32 Oil Consumption


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The L32 in my 04 Comp G is starting to consume oil at a somewhat alarming rate for only having 155k... It's burning one quart of oil every 2500 miles. I'm thinking that this may be due to the rings being coked up. Is there any way to remedy this, short of rebuilding it?

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No. The valve cover gaskets and intake gaskets have already been replaced. It doesn't leave any oil puddles under it while parked and my exhaust tips consistently turn black after cleaning them.

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Does that still have the manifold mounted PCV like the plastic intakes? If so, I'd check it for proper operation and sealing. If it's bad, not there, or the seal is broken, it will suck oil from the crankcase.

I generally don't see stuck rings on these engines.

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I'll have to check that out. In all honesty, this car was ragged on pretty hard and not maintained at all before Buck or I had it, so I wouldn't at all be surprised if it has internal issues of some kind. I just thought coked rings would make sense if it wasn't maintained.

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I wanna say I replaced the PCV valve when I went through and regasketed the whole top end, can't remember for sure though

 

ive bad luck with many aftermarket PCV valves id highly suggest the acdelco valve or reinstall the original

 

sure wouldnt hurt to pop the valvecovers to inspect the seals but ive had plenty of aftermarket pcv valves cause issues on tons of cars

 

the SIII and SII use the same style of valve seals. i believe umbrella seals went out with the old sbc's and lc2's back in the 80's

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I've seen several SII upper intakes replaced and the PCV sealing oring, the spring or the PCV valve missing

because it wasn't transferred to the new intake. The odd thing was that the cars would idle close to normal even having the

vacuum leak, but suck oil. Obviously the valve itself could be shit.

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Now that you remind me of the whole spring thing setup, I'm 99% sure I replaced it, and I would've used AC Delco unless it was like twice as much or more than the competition. Wouldn't hurt anything to replace it again though

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  • 4 months later...

Bump to revisit this issue. I did an engine flush on it and it seems to have helped oil consumption a bit. It now uses half a quart every 3000 miles.

I was driving in front of my friend the other night and rolled into WOT on an onramp and I left a nice big smoky cloud behind me in the process... Not good. So I'm using oil, getting poor fuel economy (about 24 mpg mostly highway) and the car has gotten noticeably slower... What could be going on here? PCV valve is good and clean, I just replaced the plugs and wires with oem stuff, there is no check engine light... the only strange thing I noticed was on the (#5?) cylinder in the rear bank on the drivers side was really white compared to the others. Compression test on all cylinders reveals a range of 149-165 psi... Which from searching online seems normal for the boosted 3800s... I'm at my wits end with this car now... no idea what could be wrong with it and causing all these issues.

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I was driving in front of my friend the other night and rolled into WOT on an onramp and I left a nice big smoky cloud behind me in the process...

 

A half quart every 3000 is not excessive, but the condition I quoted is obviously not normal. Rings are very unlikely to be the culprit, they just don't fail these days. You have to have either a valve stem seal or valve guide problem. This is common on LQ1's (including mine) and may very well happen on L32's as well. I'd pull off the valve covers and take a look.

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Would that cause it to lose a noticeable amount of power and fuel economy too though? Something is definitely wrong with it.

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odd question, but how much pressure or vaccum builds up in your crankcase?

 

i realize this will be difficult to measure while driving, but it may give some clues.

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If it were in my driveway, it'd get a leakdown test, and a cylinder balance test. Heavy leakage past the rings indicates poor ring seal, can contribute to oil pumping. Heavy leakage past the rings can also overwhelm the PCV system. If all the cylinders aren't running properly, oil dilution will increase oil consumption and increase fuel consumption.

 

GM Top Engine Cleaner will free-up stuck rings if that turns out to be a problem. Remove spark plugs on cold engine. Reinstall with anti-seize. Warm up engine, yank plugs, squirt about four ounces of TEC into each cylinder. Install plugs VERY loosely--three-four threads is enough--keeps debris from falling into cylinder.. Wait a half-hour, turn crankshaft slowly by hand 1/3 revolution. Wait another half-hour, turn crankshaft slowly by hand 1/3 revolution. Wait until next morning. Install plugs for real, connect plug wires, start engine. Rings are probably free. I will sometimes repeat procedure with another 4 ounces of TEC in each cylinder. Have never had to do it a third time.

 

Would be nice to change oil directly after the TEC treatment (second treatment, if you do two) and warming the engine again.

 

Valve stem seals are certainly worth a look. I've seen wiped-out exhaust valve guides so bad that they puffed exhaust into the valve cover area. Again, overwhelms PCV and causes an oil leak into the exhaust stream.

Edited by Schurkey
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