Ca18det exaust smoking on deceleration

[1.8turboterror]

I have a built ca that is now smoking on Deceleration. The motor has 10k on it could it be my Ring's or just faulty Valve Seals? Are ca's known for blowing valve seals?

[meminto]

Could be.. But it sounds like a similar issue I had on a previous build..

The oil ring gap was too large, on acceleration through WOT there was a little fuel smoke, however on return throttle it belched oil smoke..

Conclusion that the oil ring was expanding fine under load, but when it was contracting on return throttle the large gap allowed oil through to bores...

Something to think about...

[s13drifter88]

Mine did that when I was running the stock turbo on it that came with the swap. It didnt smoke at WOT or jut driving normally but on decel after a hard pull it would smoke. I replaced it with a red top t25 and it stopped

[sjbsuperman1425]

i also had this problem since I had the car, but I also had a idle hunt which when it would idle down, i would get smoke. Now, not even two months ago, my turbo seized and I'm upgrading to a T28, but I have no idea if the two are related.

To add though, none of my plugs ever had traces of oil in the cylinders.

[1.8turboterror]

Thanks guys for the feed back. I have a brand new billet ball bearing precision 6262 turbo on her so I doubt its my turbo. Could be gap on piston rings which I really hope it is not. I had the motor bored only 1 one thousandth's over and put stock bore aria pistons in thinking they would expand slightly at high boost because they are forged and I had read to do this with forged pistons on high boost applications.

[sjbsuperman1425]

it could be your PCV system. I know caught alot of blow by in my intake side catch can through the summer so if that oil is making it through, it could cause the smoke possibly?

[boost_boy]

Thanks guys for the feed back. I have a brand new billet ball bearing precision 6262 turbo on her so I doubt its my turbo. Could be gap on piston rings which I really hope it is not. I had the motor bored only 1 one thousandth's over and put stock bore aria pistons in thinking they would expand slightly at high boost because they are forged and I had read to do this with forged pistons on high boost applications.

I'd be wary of that type of over-bore you speak of. If you went 1000ths over bore and didn't measure the ring gaps, then that could be your problem. If you felt a need to bore, you should have went 20 thousandths over and move to slightly bigger pistons.

[float_6969]

I'm with Dee on this one. Most competent engine builders will want your pistons in hand, with the spec sheet showing what the piston to bore clearance is supposed to be before they start boring the block out, and it's for this exact reason. Also, you should ALWAYS check your ring gap, for EVERY ring, for EVERY cylinder when you build a motor.

[Buddyworm]

How is your crankcase ventilation system routed?

[Woods Crasher]

Sorry man. It is your ring gap. On deceleration you are pulling very high vacuum and oil is getting by