1980 Smoking when decelerating
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Instructor
Joined: Aug 2002
Posts: 240
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From: In the drivers seat of a Corvette In Ks
1980 Smoking when decelerating
Any Ideas?
I have a 1980 that runs great, but is smonking when I decelerate or take my foot off the gas. This is what I have checked or done.
1. I changed the valve stem seals.
2. Checked the intake, carb, & distributor by spraying starter fluid around all the gaskets at idol. No increase inceleration.
3. Put in a new pcv valve and checked all vacuume line for oil, all clean and dry.
4. Pulled spark plugs to see if they were foul-up no signs of oil all look good. Thought it might be a oil seal or piston ring.
Any other idsas? I'm thinking leak down test just to know.
I would appreciate any help or ideas you might have.
Thanks
I have a 1980 that runs great, but is smonking when I decelerate or take my foot off the gas. This is what I have checked or done.
1. I changed the valve stem seals.
2. Checked the intake, carb, & distributor by spraying starter fluid around all the gaskets at idol. No increase inceleration.
3. Put in a new pcv valve and checked all vacuume line for oil, all clean and dry.
4. Pulled spark plugs to see if they were foul-up no signs of oil all look good. Thought it might be a oil seal or piston ring.
Any other idsas? I'm thinking leak down test just to know.
I would appreciate any help or ideas you might have.
Thanks
Heel & Toe
Joined: Apr 2009
Posts: 21
Likes: 0
From: Selma Alabama
When an engine smokes during decel only it is usally valve guide seals. Did u replace the exhaust seals as well. And are they properly seated. The excess vacume created during decel is what sucks in the oil.
1 check the oil return ports inside the heads. make sure oil isn't pooling up on top of the heads
2 while in there make sure valve seals are properly seated intake and exhaust.
3 clan the pvc valve and hose and port at intake, make sure there are no restrictions
4 clean the fresh air port on the other valve cover, make sure no restriction.
5 test, check for smoke during decel, if engine still smokes, broken ring most problebly.
MIKE
1 check the oil return ports inside the heads. make sure oil isn't pooling up on top of the heads
2 while in there make sure valve seals are properly seated intake and exhaust.
3 clan the pvc valve and hose and port at intake, make sure there are no restrictions
4 clean the fresh air port on the other valve cover, make sure no restriction.
5 test, check for smoke during decel, if engine still smokes, broken ring most problebly.
MIKE
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Joined: Aug 2002
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From: In the drivers seat of a Corvette In Ks
Thread Starter
Instructor
Joined: Aug 2002
Posts: 240
Likes: 1
From: In the drivers seat of a Corvette In Ks
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Burning Brakes
Joined: Aug 2006
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From: Eastern North Carolina
Do the valve seals fit tight on the guide boss. If they don't then they could act like a pump when the engine is running and pump oil into the guide. I'm assuming your heads are 624's with no mods. Can you tell us what color the smoke is?
Tim
Tim
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From: In the drivers seat of a Corvette In Ks
Tim the smoke is white and valve stim seals pushed down on the stims very tight. I have not lost any antifreeze so I can't be burnning it up, it's got to be oil.
Burning Brakes
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From: Eastern North Carolina
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From: Dayton, Ohio
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From: In the drivers seat of a Corvette In Ks