Burning Oil ?????
11-20-2004, 12:48 PM
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Burning Oil ?????
Hey all,
Here's the deal: 100K miles plus on motor, pulled it out to replace the heads (with rebuilt ones), did a mild port and polish on heads, intake, runners, plenum. Now after being put back together, I am burning oil in cylinders #1 and #3 verified by plugs.
Most of the oil is burning in #1 and only a small amount in #3.
Before I tear the head back off I wanted to get some opinions on where to look for this problem. Possible bent valve? Intake manifold sucking oil from the lifter valley? I say bent valve because on the first attemp to set lash I had either #1 or #3 (can't rememer which) too tight. Oh yeah car did not smoke or burn oil prior to me going in there and I didn't mess with the bottom end at all as the cross hatch was still plainly visible in the bores.
91 Z with 305 TPI and 5speed
TIA for any help
Here's the deal: 100K miles plus on motor, pulled it out to replace the heads (with rebuilt ones), did a mild port and polish on heads, intake, runners, plenum. Now after being put back together, I am burning oil in cylinders #1 and #3 verified by plugs.
Most of the oil is burning in #1 and only a small amount in #3.
Before I tear the head back off I wanted to get some opinions on where to look for this problem. Possible bent valve? Intake manifold sucking oil from the lifter valley? I say bent valve because on the first attemp to set lash I had either #1 or #3 (can't rememer which) too tight. Oh yeah car did not smoke or burn oil prior to me going in there and I didn't mess with the bottom end at all as the cross hatch was still plainly visible in the bores.
91 Z with 305 TPI and 5speed
TIA for any help
11-20-2004, 03:14 PM
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Car: 83Z28 HO
Engine: Magnacharged Dart Little M 408
Transmission: G Force 5 speed
Axle/Gears: Moser 9" w/Detroit Trutrac
Easiest thing to do first is to check the intake gasket. Just replace it, and be sure everything's cleaned up nice and install new gaskets. Be liberal with the sealer.
It's also possible that when you bent a valve, you destroyed your valve guide too. I assume your seals are OK?
And yet another possibility is that when you put good heads on a high milage engine, your cylinder pressures/vacuum goes up due to good sealing valves, and now since you have 100K on the engine, it's getting oil up past your rings. Not as likely, but not impossible.
A dry/wet compression test will tell you if the rings are an issue.
But I feel for ya man, I'm having oil burning problems myself and have a recent post on it.
I'm thinking your problem isn't as serious as mine since your problem is on two adjoining cylinders. Good luck with it!!
It's also possible that when you bent a valve, you destroyed your valve guide too. I assume your seals are OK?
And yet another possibility is that when you put good heads on a high milage engine, your cylinder pressures/vacuum goes up due to good sealing valves, and now since you have 100K on the engine, it's getting oil up past your rings. Not as likely, but not impossible.
A dry/wet compression test will tell you if the rings are an issue.
But I feel for ya man, I'm having oil burning problems myself and have a recent post on it.
I'm thinking your problem isn't as serious as mine since your problem is on two adjoining cylinders. Good luck with it!!
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