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White exhaust when starting 1st time.

USD03745

Member
Joined
Nov 28, 2006
Messages
8
Location
Atlanta
Corvette
1990 White Coupe
My 1990 coupe w/ L98 (aluminum heads) puffs a white cloud out of the exhaust when the car is first started. It lasts less than a minute and does not happen again after that until I start it again the next day or couple of days. It does not appear to be oil (the dipstick level has not moved). Any ideas?
 

G Winter

Well-known member
Joined
Aug 21, 2004
Messages
2,177
Location
NW Iowa
Corvette
1990 red convert 6 sp
White is usually coolant in the combustion chamber or in the exhaust ports.
I think you may have a head gasket leaking or a cracked head. Is your coolant level going down at all ? If you do have a leak it is very small at this point and you may be able to stall a costly repair with stopleak. GM has a very good product that I understand is put in all new cars. I have used it often with good results. I have had the repair last over 2 yrs.


Glenn
:w
 

bradfordsvettes

Well-known member
Joined
Mar 28, 2001
Messages
549
Location
Boston, MA area
Corvette
jewel blue 61.cranberry 69 t-top.black rose 92
my guess is valve seals it is very common on these motors it is a fairly pricey repair it could be done by a backyard guy with some experience steve
 

Toms007

Moderator
Joined
Sep 24, 2004
Messages
6,483
Location
Southwest Kansas
Corvette
2007 Atomic Orange Coupe
WHITE smoke would indicate coolant. I'm with G Winter on this one, get some Bars leak and hope that it takes care of the issue, at least for a while.
 

jrzvette

Well-known member
Joined
Feb 11, 2005
Messages
287
Location
NJ
Corvette
1969 RED SB COUPE, 1993 BLACK ZF6 COUPE
Does it smoke every day or only under certain weather conditions (cool, damp)?

Water is a byproduct of combustion and what you're seeing could be condensed water vapor. Once the exhaust heats up the water evaporates.
 

Florida Guy

Well-known member
Joined
Oct 16, 2003
Messages
166
Location
Florida
Corvette
'96 Torch Red LT4
If you have a coolant leak a pressure test of the cooling system should detect it. A full service gas station or a radiator shop will probably do it for free. They replace the cap with a pressure gage, pump it up and watch the gage. If you have a leak, the gage should drop. I wouldn't put stop leak in it until I was sure it needed it.
Does your oil dip stick have a milky looking substance on it, indicating water in the oil?
If the above does not indicate a water jacket leak I would think it is leaky valve stem seals. When the car sits for a period of time, oil will sometimes leak past the seal and down the valve stem. When the engine is started the oil burns off and appears as light gray in the exhaust for a few seconds.
Coolant would be white steam.
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,547
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
White is usually coolant in the combustion chamber or in the exhaust ports.
I think you may have a head gasket leaking or a cracked head. Is your coolant level going down at all ? If you do have a leak it is very small at this point and you may be able to stall a costly repair with stopleak. GM has a very good product that I understand is put in all new cars. I have used it often with good results. I have had the repair last over 2 yrs.


Glenn
:w
I agree!!! Could even be a Intake at head leak,I've seen this, only leaks after shut down as Cooling down!!! Check all the bolts in the Intake!!:upthumbs
 

jsinga

Well-known member
Joined
Nov 23, 2001
Messages
280
Location
Savannah, GA, USA
Corvette
87 Silver Coupe Way over 200k miles
Take a wiff of the smoke. If it's antifreeze you'll get the sweet smell.
It's just old and has hard valve seals. For the agravation just drive it! Take care of it when the engine is rebuilt.
You won't find a 80's vette that doesn't do what you are talking about if it's orginal. Even it doesn't have many miles on it.
My 215k mile 87 does it and I don't put a quart of oil in it between changes.

JS
 
L

Louis Bartay

Guest
I had a 66 GTO, back in the day..that had a auto trans that had a vacuum kick down valve that was bad and the auto trans fluid would suck up into the intake where it gets it's vacuum from and white smoke came out of the exhaust.

If not and you have a manual trans, my guess is old valve guide seals. Just a thought. Let us know.
Louis
 

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