Good Compression, No Leaks, No Blue Smoke, Using 1 qt per Tank of Fuel

[Fleetw00d]

My 90 LX (F22A1), after having sat for long periods of time while replacing the quarter panels is now using a quart of oil every tank of gas (~350 miles). 310,000 miles, never had the head off. How much oil can an engine burn without smoking? Compression is 190+ in all cylinders (checked after pulling plugs and the oil in the holes draining into the cylinders). There was some oil in the spark plug holes, but no leaks that leave anything on the ground or on the underside of the car. Plugs are not fouled. No oil in the coolant. No other place for it to go other than through the combustion chambers.

If the compression is good, does that mean that most of the oil is probably going through the valve seals? I have an F22A1 with about 161,000 out of another car, but I'd rather not swap the entire engine (and I may have a buyer for the bottom end). I'm thinking along the lines of refurbishing the lower mileage head and installing it.

[oyajicool]

If that much oil is leaking, for sure, you will see a pool of oil on the ground after you park it. Since you are not seeing that, it must be burning.

General rule of thumb is that if you see smoke when accelerating, it's the cylinders as suspect; if you see smoke when decelerating, it's the valve seals as suspect.

Have a chase car and observe the tail pipe.

[Joey GT-R]

I like his logic. My vote is that your rings are just really bad. If that is the case, I would let that prospective buyer know ahead of time to avoid any unpleasantries.

[Fleetw00d]

I like his logic. My vote is that your rings are just really bad. If that is the case, I would let that prospective buyer know ahead of time to avoid any unpleasantries.

I have a buyer who wants the block on the loose motor (161,000 miles), not the block in the car (310,000). If the rings were really bad, wouldn't the compression be low?

[oyajicool]

You had oil poured into the barrels due to leaky oil seal. That oil works as sealant for the rings, bringing readings up.
The gauge may be reading in your favor, too.

[93redcb7]

Also check your pcv valve, that could be creating blow-by... always check the cheap easy parts first

[reklipz]

You had oil poured into the barrels due to leaky oil seal. That oil works as sealant for the rings, bringing readings up.
The gauge may be reading in your favor, too.

I agree with this. Replacing those plug well seals and gaskets is a fairly simple process, and is easily done in coordination with a valve-lash adjustment if you're due for that.
I've had two compression testers give readings varying by 30+ psi; one being a parts store rental, and the other being owned by a friend.

Also check your pcv valve, that could be creating blow-by... always check the cheap easy parts first

Wouldn't this be burned in the cylinders, leading to smoke at the tailpipe?

[SOHC-FTW]

Compression has little to do with worn or gunked up/stuck oil rings. This is what im dealing with on my dd 94 celica great compression on all 4, 10-20% leak down, smokes like a train an then some it burnt a little over a quart of 15w40 in 30 minutes.

Usually valve stem seals or guide issues only smoke at start up, but i have seen completely trashed heads smoke throughout the band, more so on decel.

[wed3k]

yea it could be clogged up oil control rings. thats what im fighting right now on my dad's is300. since hes had the car, it has probably already went through 20 quarts lol. can't be good for the catalytic converters.

[Fleetw00d]

I agree with this. Replacing those plug well seals and gaskets is a fairly simple process, and is easily done in coordination with a valve-lash adjustment if you're due for that.
I've had two compression testers give readings varying by 30+ psi; one being a parts store rental, and the other being owned by a friend.

Wouldn't this be burned in the cylinders, leading to smoke at the tailpipe?

I know the plug well seals are fairly easy (last time I pulled the plug wires they were clean), but if it needs valve seals, I might as well have the one head redone with new valve seals, plug well seals, etc. and ready to swap on. The amount in the plug wells doesn't account for anywhere near what I'm putting in it. Maybe I'll recheck compression after a little driving to clear the cylinders of oil.

PCV can't create blowby, it just allows blowby to be introduced into the intake, which should result in smoke at the tailpipe.

[oyajicool]

The amount in the plug wells doesn't account for anywhere near what I'm putting in it.

I hope you know that the oil that collected in plug wells are not getting into the combustion chambers until you remove the spark plugs. Thus, it has nothing to do with oil consumption (burning).
If you blow it out prior to removal of spark plugs, it will not affect reading of compression.
If your oil control rings are allowing excess oil in combustion chamber, you'll see good compression test result and high oil consumption.

http://freeasestudyguides.com/pcv-system.html

[reklipz]

Thanks oyajicool for that link. Some good info (and clarification) in this thread.

I hope you know that the oil that collected in plug wells are not getting into the combustion chambers until you remove the spark plugs. Thus, it has nothing to do with oil consumption (burning).
If you blow it out prior to removal of spark plugs, it will not affect reading of compression.

I imagine he does know this and was simply speaking about it because I brought up fixing that issue. Always good to clarify though, .

--
edited for clarity

[SOHC-FTW]

yea it could be clogged up oil control rings. thats what im fighting right now on my dad's is300. since hes had the car, it has probably already went through 20 quarts lol. can't be good for the catalytic converters.

Read somewhere that toyota said it was normal/acceptable to burn upto 1.5 quarts every oil change. Now this was for most 90's engines not sure about the newer 2j.

[wed3k]

Read somewhere that toyota said it was normal/acceptable to burn upto 1.5 quarts every oil change. Now this was for most 90's engines not sure about the newer 2j.

the bottom end should be the same as the supra. the top end has vvti.

you can run a head without valve seals and it still won't burn a quart....bad exhaust guides on the other hand will caue it to smoke pretty bad.

[HondaFan81]

Reference thread below....you could have similar concern.

http://www.cb7tuner.com/vbb/showthread.php?t=148485