Smoke on deceleration; why?

**Sam-SS** · 10-07-2007, 06:55 AM

I have had my Camaro SS with engine mods on the dyno for going on to four different sessions. The engine is now taken to blowing a bunch of white smoke after running it up to about 6300 RPM and the smoke occurs when shutting down. It does not seem to do it much under power. Also, does not do it on the street, unless it is really turned up. It seems to be using a bit more oil.

Anyone have any thoughts on the likely cause?

...>>Sam

**sreve** · 10-07-2007, 07:17 AM

valve seals

**98ls1blackbird** · 10-07-2007, 07:48 AM

I agree.

**Sam-SS** · 10-07-2007, 08:10 AM

Originally Posted by sreve

valve seals

Would valve seals not belch out smoke on a cold start?
My dated information from yesteryear is remembering
that when sitting, the oil would leak past bad seals and
into the chamber causing smoke on a cold start. Am I
wrong in this?

Thanks for the help.

...>>Sam

**bigrondownhiller** · 10-07-2007, 08:32 AM

will it do this if you rev it in the driveway? could be some condensation burning off.

**Sam-SS** · 10-07-2007, 08:38 AM

Originally Posted by bigrondownhiller

will it do this if you rev it in the driveway? could be some condensation burning off.

Not really, it is when the engine has been revved to the
limiter and then decelerate.

**Rivi** · 10-07-2007, 08:47 AM

rings

**Sarge** · 10-07-2007, 08:55 AM

Your getting oil in your combustion chamber when decelerating due the vacuum. This can be either valve seals or rings. AutoRX that bad boy. Now.
http://www.auto-rx.com/
Replace your PCV valve. Do you have a catch can?

**Sam-SS** · 10-07-2007, 09:36 AM

Originally Posted by Sarge

Your getting oil in your combustion chamber when decelerating due the vacuum. This can be either valve seals or rings. AutoRX that bad boy. Now. http://www.auto-rx.com/
Replace your PCV valve. Do you have a catch can?

I have a bottle of AutoRX that I bought for my other car and I could use that. However, the car has had Mobile 1 and Royal Purple synthetic in it for all of its 72k miles, changed faithfully on a 5k miles schedule. The problem only developed after a series of dyno runs over the last two months. Should it still need the AutoRX treatment?

How would one isolate for sure whether it is rings or seals?

As for the PCV I believe that one of the tuners that worked on it removed the PCV. No catch can.

...>>Sam

**Rivi** · 10-07-2007, 09:45 AM

right there is the trouble...you can't remove the pcv system.

**Sarge** · 10-07-2007, 02:23 PM

Oh shit. Kick that guys ass. How is your vaccum configured then?

**fatjet00** · 10-07-2007, 05:55 PM

I would pull out all your spark plugs and screw a compression gauge in each cylinder. Record each PSI on each cylinder. If you come across one or more that are considerably lower than the others, squirt some motor oil in the spark plug hole, re-check your compression. If it increases, you have issues with your piston rings. If the reading stays the same, you got either worn, loose valve guides, or worn valve seats. This procedure will tell you if it's rings or valves. Good luck. You can purchase a compression tester, gauge from any auto parts store.

**LETHALxLS1** · 10-07-2007, 06:17 PM

In any car I have seen with bad valve seals if you let the car idle for 3-4 minutes and then take off it will puff smoke out the pipes and that smaoke usually isnt white. I would hook the pcv back up and put a catch can on her.

**Sam-SS** · 10-10-2007, 01:09 AM

Originally Posted by Sarge

Oh shit. Kick that guys ass. How is your vaccum configured then?

After the nice feedback that I got here, I am in the process of hooking the PCV back up. Once I do that I will see how it goes and move on to the other steps that have been suggested. Thanks much folks.

...>>Sam