Dharn55

The AOS can be changed with the engine in the car, but what a PITA. I think the estimated time is 10-12 hours. You have to remove most of the intake to get at it, and thien it is still difficult . Almost easier to drop the engine. A good mech can drop the engine and reinstall in in about 8 hrs. Once the engine is down the AOS is a 15 minute job.

rxjohn

Thanks Dharn,

rxjohn

btw, some pictures.

rxjohn

Oh.. and no white smoke from my exhaust... could it still be AOS? And when I open the oil cap while idling, the idle does drop and roughens... then smoothes out again. But the idle does not die. When I put my hand over it, I can feel the vacuum. I am going to take the air intake off to get a better view of the oil leaks.

SH || NC

Nice pictures!

Macster

Not all AOS failure modes produce oil smoke at start up, at least not at first. Also, not all AOS failure modes generate exceptional engine vacuum.

The engine's behavior when you remove the cap is normal.

I would advise *not* removing the intake manifold unless you absolutely have to. If the intake manifold is not leaking or otherwise a problem, best to let sleeping dogs, and an air tight intake manifold alone.

You can remove enough of the intake system up to the manifold to then remove the throttle body and check it for signs of oil or dirt contamination. This I found during the first AOS failure. The TB was oily and the butterfly valve had a drop of oil ready to fall off its bottom edge. A cleaning and reinstall fixed the engine stumble and mild idle hunting, for a while, but the symptoms came back as (unknown to me at the time) the failing AOS supplied copious amount of engine oil vapor from the crankcase to the hose connection just behind the TB. There was a lot of oil at this connection too.

The AOS proper could be ok, but its housing may have developed a crack, or the pleated rubber hose could have split, or the hose from the AOS to the manifold could be cracked. Any one of these could be the source of the oil leak and yet not be bad enough to generate any engine symptoms. Whether one of these possibilities is the cause is a job for you to eliminate each and every one.

The oil leak could be coming from somewhere else. Oil leaks are hard to trace cause these engines are in a quite confined and hard to work in space. Air flow around and through the engine compartment can blow oil up and even forward from its leak point.

Some places will wash/degrease the engine and then put a harmless dye in the engine oil. The engine is run and a black light is shined onto the engine and the oil leak area will glow when the black light hits the oil with the dye in it. Sometimes the oil leak is a tiny crack or pinhole in a hose. Other times it will show up as a bright but short thin line along a gasket or around a seal or plug.

Based on what you've posted I do not think you have enough to justify replacing the AOS. It may be going bad, but if so it has not gone bad enough to make it clear it is going bad.

I'm not in favor of washing these engines but sometimes one has to do what he has to do.

Thus you could consider washing the engine -- I use Gunk and spray it on a warm (not hot!) engine, let it sit, then rinse with if I can get it warm to hot water. I carry buckets of it out to the car or if I can run a hose to a convenient hot water faucet I do that.

Then after a good rinse start the engine -- serpentine belt will likely squeal -- and let it idle and warm up. Leave engine cover open. Let engine get up to operating temperature or close to it. Shut it off and let it cool enough you can work around it without getting burnt.

Then with a good light and a small mirror on a swivel stick look at engine and all the various external parts, hoses, lines, seals, plugs, gaskets, etc, very carefully for any signs of fresh oil seeage or leakage.

If you see none, take car for a drive. Just a normal drive but run engine up and down rpm range and again get it fully up to operating temperature.

Bring car back home and again let the engine cool. Perform the same inspection again and again look for the first traces/signs of an oil leak.

If you spot it chances are good where you spot it will provide you with a good clue as to just what is the source of the leak.

Caution: If at any time -- except immediately after engine start after washing -- the engine begins to run rough, emit smoke, exhibit any untoward behavior at all, shut off the engine immediately and arrange to have to have it flat bedded to a qualified shop for diagnosis of the rough running or other severe symptoms.

Sincerely,

Macster.