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Puff of smoke on start up

Ruby Fan

Well-known member
Joined
Oct 7, 2004
Messages
189
Location
NY
Corvette
1985 Black Beauty Coupe, 93 Ruby, 96 CE vert
I have an '85 L98 that is just shy of 50K miles. When I first start it up cold, a puff of blue smoke will appear. Thereafter the rest of the day, no smoke. I know this means a little oil blow-out/burn up, but does this normally happen to many of these motors? I don't use this car every day, usually only on weekends, so there is always a long time between cold starts. Thanks & Happy Holidays :cool
 

Ruby Fan

Well-known member
Joined
Oct 7, 2004
Messages
189
Location
NY
Corvette
1985 Black Beauty Coupe, 93 Ruby, 96 CE vert
Thanks. Shame that it happens to an engine with less than 50K on it. I don't feel I would have a reason to pull off the heads, so I guess I'll live with it and keep an oil check.
 

G Winter

Well-known member
Joined
Aug 21, 2004
Messages
2,177
Location
NW Iowa
Corvette
1990 red convert 6 sp
I would say that your valve seals have dried out. If the seals are still the same as they were in the late 70s you can change them without taking the heads off. You use an adaptor such as a compresion tester has on it, on an air hose. Remove the valve covers and rockers. Attatch the air hose to each cylinder and with a special tool remove the valve springs, replace the seals and replace the valve springs. If your mechanical at all it isn't really hard to do.

Glenn
:w
 

bosshogg

Well-known member
Joined
Jul 15, 2006
Messages
56
Location
Indiana
Corvette
1988 Coupe
Glenn is right...it is a fairly simple job that I have done a couple of times. He is also right in telling you to replace the springs and keepers at the same time. Might also be a good time to redo your valve covers. No more smoke...Life is GOOD
JOHN
 

Ruby Fan

Well-known member
Joined
Oct 7, 2004
Messages
189
Location
NY
Corvette
1985 Black Beauty Coupe, 93 Ruby, 96 CE vert
That sounds like something I would like to do. Does the air pressure loosen up the seals? What are the seals made of? Soft bronze?
 

LT4man

Well-known member
Joined
Jun 25, 2003
Messages
2,217
Location
Chicago
Corvette
96 Collectors Edition LT4
Seals are made of rubber. Go to your neighborhood auto parts store and ask to see a set of them.

The rubber gets hard over time. Especially with such low miles on the engine, the rubber gets dried out and shrinks and cracks. Then the oil has a way of running down past the valve stem into the combustion chamber where when it burns you see the smoke out the tailpipe.

The air pressure keeps the valves closed while you remove the valve keeper. Otherwise the valves would fall into the cylinder and you would have to remove the cylinder head to retrieve the valves.

SAVE THE :w
 

jmrl98

Member
Joined
Oct 19, 2006
Messages
19
Location
Hazel Park MI
Corvette
85 4+3
62K on my 85, and same thing. Castrol high mileage dino oil helped quell the puff to a mild exhale, and only on initial start up of the day. It says it reconditons seals, which I didn't believe but thought I would try, and I concur with them. It reconditioned them enough for it to be barely noticeable on some days. But the seals are bad - any minute puff on start up indicates that. Castrol will give you some more time at best.
 
Joined
Jan 15, 2004
Messages
2,240
Location
Northern Indiana
Corvette
1987 Z52 Black Convertible
These cars sitting is worse then driving them. Like everybody else has stated it is normal, and wont bother anything. I have seen LS1's with low miles do the same thing, dont feel bad ;).
 

jmrl98

Member
Joined
Oct 19, 2006
Messages
19
Location
Hazel Park MI
Corvette
85 4+3
Man, no lie vettefan 87 - my buddy has a 97 saleen mustang with 11K that puffs WORSE than my vette. I told him that is gonna be his first repair when he comes to acknowledge it......he is in total denial.
 

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