Blowing Smoke After Idling - Otherwise Known as ?What Do I Order From Jerry?? - ZR-1 Net Registry Forums

Erik · 10-30-2021

Again, looking for some help.

Of late, I?ve noticed a couple of times when the car is warm, and sits running for a while, it blows a puff of smoke out of the back. Looks like it?s gotten a bit worse of late, so I did a little investigated today. She did get a good Eye-talian tuneup today, with some ZR-1 appropriate highway speeds. Through all of it, no signs of any smoke. Actually, I?ve been impressed with how little oil it burns overall. So I don?t think there are any major issues inside the engine.

Poked around here a bit, and came up with some references to the fuel somethung gaskets going bad, and letting oil up into the plenum, which then burns off in the first acceleration. Sounds like what I am experiencing. Oh, and mine only does it out of the right exhaust pipe.

Anyone have any thoughts on this? What parts do I need to address it? What else is worth doing while it?s this far apart?

Thanks again, everyone.

TX '90 ZR1 · 10-31-2021

My understanding is that it is quite normal for the earlier engines to puff a bit of smoke on occasion. I think the early ones did not have valve guide seals and allow a bit of oil to enter the combustion chamber. I know my '90 will smoke a bit on occasion after idling.
A reasonable amount of oil usage is not necessarily a bad thing. When I was building engines for my race planes we always set them up to use a bit of oil for extra lubrication under extreme temperature and stress situations.
Only fly in the ointment I see with yours is that it only smokes on one side, A bit curious, but still not something to worry about if everything else checks normal.

Erik · 10-31-2021

Looks like what I was thinking of was the lower injector housing gaskets.

Erik · 10-31-2021

Quote:

Originally Posted by TX '90 ZR1

My understanding is that it is quite normal for the earlier engines to puff a bit of smoke on occasion. I think the early ones did not have valve guide seals and allow a bit of oil to enter the combustion chamber. I know my '90 will smoke a bit on occasion after idling.
A reasonable amount of oil usage is not necessarily a bad thing. When I was building engines for my race planes we always set them up to use a bit of oil for extra lubrication under extreme temperature and stress situations.
Only fly in the ointment I see with yours is that it only smokes on one side, A bit curious, but still not something to worry about if everything else checks normal.

Thanks.
Looking to get in under the plenum and have a few things addressed, so if the is something doable, I?d like to figure it out. Otherwise, it does run well.

Erik · 11-01-2021

Just bumping this up. Could use some advice from the many gurus on the site!

Erik · 11-01-2021

Oh, and if we replace the lower injector housing gaskets, is there anything else worth doing while we are in there? I don?t like to replace aging or wear parts if I don?t need to. Prefer to do a job just once.

rkreigh · 11-10-2021

until you diagnose the problem I sure wouldn't order parts. If you do a plenum pull to investigate it's worth getting new gaskets even though sometimes the old ones can be reused.

lots of sealing issues can cause oil to enter the combustion. Relatively common for the breather box screws to loosen up and hoses go bad.

Find out first if you even have a problem. check oil and coolant levels to see if they are stable.

Jerry's guide in the other post and a good service manual and keep posting here!! Good luck finding the issue.

10-30-2021	#1
Erik Join Date: Nov 2016 Location: New Brunswick Posts: 961	Blowing Smoke After Idling - Otherwise Known as ?What Do I Order From Jerry?? Again, looking for some help. Of late, I?ve noticed a couple of times when the car is warm, and sits running for a while, it blows a puff of smoke out of the back. Looks like it?s gotten a bit worse of late, so I did a little investigated today. She did get a good Eye-talian tuneup today, with some ZR-1 appropriate highway speeds. Through all of it, no signs of any smoke. Actually, I?ve been impressed with how little oil it burns overall. So I don?t think there are any major issues inside the engine. Poked around here a bit, and came up with some references to the fuel somethung gaskets going bad, and letting oil up into the plenum, which then burns off in the first acceleration. Sounds like what I am experiencing. Oh, and mine only does it out of the right exhaust pipe. Anyone have any thoughts on this? What parts do I need to address it? What else is worth doing while it?s this far apart? Thanks again, everyone. __________________ 1990 ZR-1 # 996 "All Corvettes are red. The rest are mistakes." - John Heinricy

10-31-2021	#2
TX '90 ZR1 Join Date: Oct 2017 Location: TX Posts: 2,037	Re: Blowing Smoke After Idling - Otherwise Known as ?What Do I Order From Jerry?? My understanding is that it is quite normal for the earlier engines to puff a bit of smoke on occasion. I think the early ones did not have valve guide seals and allow a bit of oil to enter the combustion chamber. I know my '90 will smoke a bit on occasion after idling. A reasonable amount of oil usage is not necessarily a bad thing. When I was building engines for my race planes we always set them up to use a bit of oil for extra lubrication under extreme temperature and stress situations. Only fly in the ointment I see with yours is that it only smokes on one side, A bit curious, but still not something to worry about if everything else checks normal. __________________ Kenny 1990 #442

10-31-2021	#3
Erik Join Date: Nov 2016 Location: New Brunswick Posts: 961	Re: Blowing Smoke After Idling - Otherwise Known as ?What Do I Order From Jerry?? Looks like what I was thinking of was the lower injector housing gaskets. __________________ 1990 ZR-1 # 996 "All Corvettes are red. The rest are mistakes." - John Heinricy

11-01-2021	#5
Erik Join Date: Nov 2016 Location: New Brunswick Posts: 961	Re: Blowing Smoke After Idling - Otherwise Known as ?What Do I Order From Jerry?? Just bumping this up. Could use some advice from the many gurus on the site! __________________ 1990 ZR-1 # 996 "All Corvettes are red. The rest are mistakes." - John Heinricy

11-01-2021	#6
Erik Join Date: Nov 2016 Location: New Brunswick Posts: 961	Re: Blowing Smoke After Idling - Otherwise Known as ?What Do I Order From Jerry?? Oh, and if we replace the lower injector housing gaskets, is there anything else worth doing while we are in there? I don?t like to replace aging or wear parts if I don?t need to. Prefer to do a job just once. __________________ 1990 ZR-1 # 996 "All Corvettes are red. The rest are mistakes." - John Heinricy

11-10-2021	#7
rkreigh Join Date: Jan 2004 Location: Alex VA Posts: 1,087	Re: Blowing Smoke After Idling - Otherwise Known as ?What Do I Order From Jerry?? until you diagnose the problem I sure wouldn't order parts. If you do a plenum pull to investigate it's worth getting new gaskets even though sometimes the old ones can be reused. lots of sealing issues can cause oil to enter the combustion. Relatively common for the breather box screws to loosen up and hoses go bad. Find out first if you even have a problem. check oil and coolant levels to see if they are stable. Jerry's guide in the other post and a good service manual and keep posting here!! Good luck finding the issue. __________________ 95 390 LPE ZR1 (505 rwhp) LSV = Lingenfelter Super Vette Twin Turbo 2003 Z06 (800 RWHP)