Problem with oil consumption .....

[muleskinner]

Ok, Did a pressure check and everything checked out good. Not sure where all the oil is going. The festy is using 4 quarts of oil in a week and half time. It hardly ever shows any oil burning smoke except maybe going down a hill at the end.

It has oil in the air intake, quite a bit actually. So could there be something wrong with a vacuum line even though the car runs fine? Could that be where all the oil is going?

Thanks,
Mike

[TorqueEffect]

What you are getting is excessive blowby. Basically since the piston rings are worn, allot more combustion gasses are getting by the rings and into the crankcase, causing more pressure to build in the crankcase which somehow causing more oil to be spit up into the intake through the valve cover vacuum lines.

[muleskinner]

What you are getting is excessive blowby. Basically since the piston rings are worn, allot more combustion gasses are getting by the rings and into the crankcase, causing more pressure to build in the crankcase which somehow causing more oil to be spit up into the intake through the valve cover vacuum lines.

So what would it be, if say, the piston rings where not worn??

[WmWatt]

If it's not rings it's valve guides which are easier (cheaper) to replace. A vacuum guage is supposed to show if it's the valves. See the "sticky" thread at the top of this (repair help) forum.

My friend's car burns oil but there is no smoke because the catalytic converter takes care of most of it, but the catalytic converter doesn't last very long, and it fouls the oxygen sensors too. If you stick your finger in the tailpipe on her car and drag it out it comes out black with soot. If you take her oil filler cap off with the engine running you can feel the blowby coming out the filler hole. If you remove the spark plugs the electrodes are normal but the insulator is covered with black powder. The dry compression is good, 190 on all cyclinders, but wet is 210 and I think that's worn rings but don't know how bad that difference is. We have been trying to figure out how to get the check engine light to go out so she can get it to pass the Ontario emissions test but have not been succesful yet. We removed the upstream O2 sensor (I's a Honda Civic) and cleaned it with a propane torch which got that engine code to disappear for a few days but the 420 code came on and then the O2 sensor code came cack. Running out of ideas.

[TorqueEffect]

I don't think oil can get into the intake any other way than through excessive blowby.

[Pu241]

My friend's car burns oil but there is no smoke because the catalytic converter takes care of most of it, but the catalytic converter doesn't last very long, and it fouls the oxygen sensors too. If you stick your finger in the tailpipe on her car and drag it out it comes out black with soot.

The Cat. converter isn't designed to "burn" the carbon.
Carbon burns to CO2 at 600°C in an excess of O2, your not going to see those conditions in the exhaust.
The contact time at the required temperature is not high enough either.
Once the catalyst is coated in carbon it will become non-functional, and you will not pass CO and nitrogen oxides testing.
The carbon needs to be burned off!

If you take her oil filler cap off with the engine running you can feel the blowby coming out the filler hole. If you remove the spark plugs the electrodes are normal but the insulator is covered with black powder. The dry compression is good, 190 on all cyclinders, but wet is 210 and I think that's worn rings but don't know how bad that difference is.

Those number can't be too much higher and run on 87 octane, think her problem is elsewhere.

We have been trying to figure out how to get the check engine light to go out so she can get it to pass the Ontario emissions test but have not been succesful yet. We removed the upstream O2 sensor (I's a Honda Civic) and cleaned it with a propane torch which got that engine code to disappear for a few days but the 420 code came on and then the O2 sensor code came cack. Running out of ideas.

Wonder if you don't have a failing O2 sensor period.
How many miles on it and was it properly cared for oil change, coolant, etc.?

[Eaglefreek]

Could be stuck rings. You could always try something like Amsoil P.I. or something similar.

[muleskinner]

Well, for now I put a quart of Lucas oil in with fresh regular oil (10w30). Maybe it will slow down the oil consumption temporarily.

Looking for another engine for it with low miles or a rebuild.

[zoom zoom]

Did you ever do the piston soak? If you have good compression and the engine isn't smoking really bad then the oil rings are stuck. I tore apart a GOOD running b3 with 180k from my first aspire after it sat for 6 months and the oil rings were stuck so bad I couldn't get them loose with a harbor freight pick, so I left the rings on and made a lamp. The engine sitting for so long probably let those oil rings get gummed up, like I said when we put it in. There are other options for freeing up those rings. Have you tried adding MMO to the oil? The heat and movement is there to help while the engine is running, you need something to break down the sludge. You know what you have in that engine, adding a chemical to break down the sludge (in the ringlands keeping the oil rings seized to the piston) isn't going to cause other leaks.

There are 3 piston rings on each piston, the top one is the compression ring, its doing it's job if you have compression. The bottom ring is comprised of 3 rings in itself, but as a whole it wipes the majority of oil back down the bore while the middle ring scrapes the cylinder clean of oil on each downstroke. The bottom ring is the one that gets stuck really bad.


Your intake tract and manifold already had quite a bit of oil in it from the old engine, clean it up a little and see if this engine is actually responsible for any of that. With the engine running and the oil cap off is there enough air to blow your hand off the hole with a little force or is it just enough that it would make a piece of paper flutter?

[Chobobulous]

^^
Expanding on this, when I rebuilt my b6 the little drain holes behind the rings were all clogged with carbon. It was stuck in there pretty good.