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Smoke on Deceleration

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Old 03-16-2017, 08:08 AM   #1
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Default Smoke on Deceleration

Hey Guys -

I am having trouble with my 2000 SS LS1 with smoking (I believe burning oil) on deceleration. It's a mostly stock vehicle with 74k miles on it.

I noticed no issue on it when completely stock (up until 72k miles or so) nor when I swapped an LS6 intake onto it. Late last summer, I ended up upgrading to the Hooker TD system, and this is when I noticed the issue. I assume the stock cats were mitigating the problem.

I notice anytime I get on it relatively heavily, a few seconds after letting off I get a puff of smoke, and it smells like oil really strongly. I've added a homebrew catch can (with media in it, I really tried to mimic the good aftermarket cans) and notice no difference with it connected or not.

It also does this when on the dyno - so it's not like oil is sloshing around somewhere. I did have some light oil buildup in the stock LS1 intake, but nothing alarming at all after 72kish miles of driving - it really looked decent to me. I also don't notice it consuming oil drastically or anything. When I hooked up the catch can, I also put in a glass fuel filter. I see a little oil vapor coming through, but I don't see anything that would cause something like this. I am not ruling out the possibility of it being PCV driven, but I don't think it is.

The video below is a good representation of what's happening. The car was on the dyno, and right before the 40 second mark when the operator lets off, watch the driver's side exhaust tip. A few seconds later, watch the passenger.



Any thoughts or experience with something like this?

Last edited by Atrus_SS; 03-16-2017 at 08:32 AM.
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Old 03-16-2017, 08:52 AM   #2
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That does not look too bad all . Didn't see much smoke under load . Is it worse on the street?
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Old 03-16-2017, 08:55 AM   #3
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It's not godawful, but it's DEFINITELY noticeable. Smells pretty bad, very noticeable in the cabin.
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Old 03-16-2017, 09:03 AM   #4
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im no expert mechanic however when that happened in the old days it was oil coming down the valves past the value seats (i think) so my first thought is time for a valve job or new ls6 heads!
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Old 03-16-2017, 09:44 AM   #5
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That was one of my thoughts - I am hoping it's valve seals rather than something internal. I thought seals could be replaced on the car, so sounds like a cam swap would be a perfect time to fix this issue
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Old 03-17-2017, 10:56 AM   #6
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My vote is valve stem seals.
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Old 03-17-2017, 01:03 PM   #7
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From what I understand, it is the stock PCV system letting oil vapors in to the throttle body. Your catch can should have resolved this issue, have you checked you routed your hoses correctly?
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Old 03-17-2017, 03:25 PM   #8
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Quote:
Originally Posted by Powers00SS View Post
From what I understand, it is the stock PCV system letting oil vapors in to the throttle body. Your catch can should have resolved this issue, have you checked you routed your hoses correctly?
I have, and I actually completely bypassed the PCV (temporarily disconnected the line and plugged the port to avoid a vacuum leak) and I still got the same result.
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Old 03-17-2017, 09:03 PM   #9
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Another vote for valve seals.
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Old 03-18-2017, 08:00 AM   #10
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textbook valve seal problem. High vacuum during deceleration is sucking oil past the seals.
I knew you would find a reason to put a cam in it.
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Old 03-19-2017, 07:22 AM   #11
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I have this same issue with mine (2001 camaro SS 73k miles) is on hard acceleration and deceleration . It blows out smoke. Buddies told me blue smoke as well. Few people told me it's my valve seals. I to believe this is your problem.
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Old 03-19-2017, 11:00 AM   #12
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Quote:
Originally Posted by lildemars09 View Post
I have this same issue with mine (2001 camaro SS 73k miles) is on hard acceleration and deceleration . It blows out smoke. Buddies told me blue smoke as well. Few people told me it's my valve seals. I to believe this is your problem.
Smoke upon acceleration usually means rings.
Smoke upon deceleration or cold start up is usually valve seals.
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Old 03-19-2017, 03:08 PM   #13
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Well that's new news to me. Hopefully that's not the case for me. I'll have to go back out and check again. Maybe it's deceleration on my car. Thanks for the clarification.
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Old 03-20-2017, 07:08 AM   #14
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Quote:
Originally Posted by farmington View Post
textbook valve seal problem. High vacuum during deceleration is sucking oil past the seals.
I knew you would find a reason to put a cam in it.
Yeah - just not in the budget this year. Sounds like a good project for next year. For this year, I'll just end up adding insult to injury to everyone I gap - I blow past 'em and then blow burning oil in their faces ;-)


Thanks for the replies, everyone - I feel much better now at least knowing it's nothing too critical and I can enjoy the car this summer.
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