exhaust smokes and low compression in one cylinder

[JayB98GST]

For the past couple of weeks my exhaust has been blowing smoke and getting worse every day. I don't notice any smoke while driving or at full boost, but its possible that it might be smoking a little bit. The only time I notice it is when I come to a complete stop and idle. It will let out a pretty big puff of smoke a couple of seconds after i put in the clutch. Then it will just lightly smoke. I can't really tell what color it is... but it looks more like white to me and it smells awful. Also, the past week, I got a cel a couple times: P0420 Catalyst System Efficiency Below Threshold (Bank 1). And I'm not running a cat and haven't been since I got the car. I looked it up and it says that one of the causes for this CEL is a bad oxygen sensor. So at first I thought maybe I was just running rich. But then I did a compression test and got 180 in cylinders 1,2, and 4 and got 130 in cylinder 3. Then I did a wet test in 3 and got about 210. I just got my engine rebuilt about 1500 miles ago. So I'm praying that it could be caused by something else besides a ring. But I don't know if thats related or not. Could it be caused by a bad valve maybe?

 

[diablos991]

Check your turbo for shaftplay and your LICP for oil.

Have you been losing coolant?

It is possible that your ring didn't seat right. You should have a leakdown test performed to pinpoint where you are losing compression on cylinder 3.

 

[JayB98GST]

No, the coolant is still full.

I will try to get it to a shop sometime this week and have a leakdown test done and i'll check the turbo and LICP tomorrow.

But if it is the ring thats causing this, can it be fixed by just dropping the oil pan, and not removing the whole engine?

 

[DarkSwatCobra]

its possible it could be your valve seals....i had 6 of mine bad and my car smoked like a mother...

 

[JayB98GST]

I checked for shaft play, and there is very little play and no oil in the LICP.

If it were a bad valve seal, I would imagine that the car would blow a big puff of smoke out when starting it cold. Thats what happened to me last time I had a bad valve seal.

 

[BOBS90TURBO]

It is not a worn valve stem seal, I would say you have a bad ring, it must have not seated properly, any real engine builder should fix it under warranty, I am going through the same problem as you right now, I just bought a used engine with good compression off ebay for $350 plus shipping.