Smoke From One Side
Thread Starter
Instructor
Joined: Jan 2007
Posts: 191
Likes: 1
From: MONTREAL QUEBEC
Smoke From One Side
My 71 350/270 is smoking blueish white from the drivers side when first started when not used for about a week. It clears up after driving 5 minutes.
I changed the valve seals and put original and umbrella seals and there is no change.
Car runs smooth and strong aside from the smoke. Engine was rebuilt 10 years ago, compression is good.
Any thoughts?
I changed the valve seals and put original and umbrella seals and there is no change.
Car runs smooth and strong aside from the smoke. Engine was rebuilt 10 years ago, compression is good.
Any thoughts?
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Do a leakdown test on it - the leakdown test will show things that a compression test won't reveal. If the top end is tight, you have a broken oil control ring or a ring sealing problem.
Intermediate
Joined: Nov 2005
Posts: 27
Likes: 0
From: Cincinnati Ohio
When your engine is cool, the heat riser valve on the passenger side exhaust manifold is closed and sends it's exhaust up through the intake manifold to heat the carb. Once the manifold heats up, the valve opens.
Smoke just at start up means the valve stem seals are worn out and wear on the value stem guides. I replaced my valve stem seals and greatly reduced smoke at start up.
Smoke just at start up means the valve stem seals are worn out and wear on the value stem guides. I replaced my valve stem seals and greatly reduced smoke at start up.
Drifting
Joined: Feb 2000
Posts: 1,591
Likes: 53
From: Central MN
vette blue.............I'm having the same problem as you ('70 350/350.) In addition to the excessive smoke at start-up, I'm also experiencing hard cold starts and dieseling (run-on.) I am not a mechanic, but here is my diagnosis:
Assuming the valve seals are worn, oil is leaking into the cylinders. Upon cold start, the oil is burning, hence the smoke. Additionally, the oil in the combustion chambers is making the cold engine start hard. I think the dieseling is caused by the carbon build up in the combustion chambers as a result of the oil "burning off."
I'm going to replace the valve seals and run some GM engine top cleaner through the engine. Hopefully, all the problems will clear up. I'll keep you all posted.
Assuming the valve seals are worn, oil is leaking into the cylinders. Upon cold start, the oil is burning, hence the smoke. Additionally, the oil in the combustion chambers is making the cold engine start hard. I think the dieseling is caused by the carbon build up in the combustion chambers as a result of the oil "burning off."
I'm going to replace the valve seals and run some GM engine top cleaner through the engine. Hopefully, all the problems will clear up. I'll keep you all posted.
Thread Starter
Instructor
Joined: Jan 2007
Posts: 191
Likes: 1
From: MONTREAL QUEBEC
vette blue.............I'm having the same problem as you ('70 350/350.) In addition to the excessive smoke at start-up, I'm also experiencing hard cold starts and dieseling (run-on.) I am not a mechanic, but here is my diagnosis:
Assuming the valve seals are worn, oil is leaking into the cylinders. Upon cold start, the oil is burning, hence the smoke. Additionally, the oil in the combustion chambers is making the cold engine start hard. I think the dieseling is caused by the carbon build up in the combustion chambers as a result of the oil "burning off."
I'm going to replace the valve seals and run some GM engine top cleaner through the engine. Hopefully, all the problems will clear up. I'll keep you all posted.
Assuming the valve seals are worn, oil is leaking into the cylinders. Upon cold start, the oil is burning, hence the smoke. Additionally, the oil in the combustion chambers is making the cold engine start hard. I think the dieseling is caused by the carbon build up in the combustion chambers as a result of the oil "burning off."
I'm going to replace the valve seals and run some GM engine top cleaner through the engine. Hopefully, all the problems will clear up. I'll keep you all posted.
Drifting
Joined: Feb 2000
Posts: 1,591
Likes: 53
From: Central MN
vette blue............As you suggested, I had a leakdown test done before I replaced the valve seals. Well, to make a long story short, it's time for a rebuild.
This car, unfortunately, is turning into money pit.
This car, unfortunately, is turning into money pit.
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Thread Starter
Instructor
Joined: Jan 2007
Posts: 191
Likes: 1
From: MONTREAL QUEBEC
Very possible its the heads too but I'd hate to change them and then find out it still smokes and then have to do rings. Leakdown test steer me in the right direction. I hope it's only just the heads too!
