Oil burning, only downhill with closed throttle

[Shannow]

It's not "compression braking", as you would get back at least the same effort, and on a hot engine some more as well.

You are effectively wasting energy by losing it across a closed butterfly, and then compressing it back to atmospheric...energy is lost, car decelerates.

My E-30 is a classic.

Slight whisp on full acceleration, slight blue puff on gear change, then full "throttle" over-run is a bit blue, followed by a great big blue billow on re-applying the accelerator...JamesBond would be proud on the getaway move.

It manages to drip oil out the air filter, even 'though the air is (always) flowing into the engine.

 

[Dan55]

+1 Sounds like bad valve guides/seals.

 

[SteveSRT8]

C'mon guys, it's the valve seals. It's not rings, as they will smoke under heavy throttle/max combustion pressures. Oil in the intake is unrelated to this issue, common on a ton of cars these days, this causes the puff on start up, too.

The high vacuum smoking is one [censored] of a smoking gun! Get some seals.

 

[rslifkin]

If it's only on decel, my guess would be either coming through PCV or bad valve stem seals.

 

[Trav]

Didn't he say it smoke after he mashes the throttle after decel down hill? Or am i not getting this right?

 

[440Magnum]

Originally Posted By: Hyrde
I'd like to get some insight into this problem..

My Corolla 4wd 1.8 7afe burns oil whenever i go downhill in gear with my foot off the gas (engine deceleration), huge amounts of blue smoke. It takes a few seconds with WOT after downhill run to clear all the smoke.


That's THE number one sign of shot rings. The high vacuum during deceleration pulls oil past the rings, the low volume of air flowing through the cylinders doesn't flush the oil out quickly, so as it sputters into the hot exhaust system it makes a lot of smoke. It will persist for a few seconds after you get back on the throttle, too. And this may not show up on a compression test either, since the oil control rings may be worn and the compression rings can still be OK.


It might be a PCV problem, but I doubt it. PCV oil consumption is usually highest at moderate throttle- coasting downhill makes the PCV valve go to high restriction mode, even though the manifold vacuum is high (it COULD be a bad PCV valve, but that would likely cause other issues).

Its not valve guides or stem seals- bad valve stem seals cause a burst of smoke after prolonged idling, say at a stop light.

All the signs point to shot rings. Sorry.