Losing oil - how to tell if valve stems or rings?

[rbutton]

1986.5 NA Supra with 143,000 miles.

Just replaced head gasket about 5,000 miles ago and used a rebuilt head from http://cylinder-heads.com/

After a few minor hiccups, running without any problems this year, except that I have to put about 1 qt. of oil in every 500-1000 miles.

No drips on the garage floor (replaced oil pan gasket about 2 years ago), looks like excess carbon at exhaust pipes, but no noticeable smoke when idling.

I'm guessing either valve stem seals or piston rings are leaking. No bottom end work ever done on this engine.

Is there a test that can tell me where the oil is leaking?

 

[toyotanos]

I installed new valve stem seals on a 2JZ that had ~1/2 of the seals not installed and it didn't use almost any oil...
I'd be looking at the rings closely- likely oil control rings carbon'd up and seized into the ring grooves.

 

[rbutton]

Is there a quick test (ie - not involving engine tear down) to confirm worn rings?

Just changed the oil. Got about 3 quarts out and it seemed "dirtier" than usual.

What is strange is that cylinder pressures were measured pretty high (180-195psi) just after head gasket repair. I would have thought leaky rings would have lowered the measured cylinder pressures.

 

[veedubin]

Is there a quick test (ie - not involving engine tear down) to confirm worn rings?

Just changed the oil. Got about 3 quarts out and it seemed "dirtier" than usual.

What is strange is that cylinder pressures were measured pretty high (180-195psi) just after head gasket repair. I would have thought leaky rings would have lowered the measured cylinder pressures.

Quick test is a leak down test. Google it.harbor freight has the leak down tester for about $30 or so. Do the test dry first then again with oil in the cylinders.

Also have someone follow you while driving. Have them look for smoke: under acceleration is rings, on decel is valve seals.

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