General Question

This applies to all petrol engines as well as VW,s I think. A small ( or larger) cloud of smoke on start up which clears immediately and then doesnt repeat for months or longer.Engine uses minimal amounts of oil between changes. I,m told its leaking valve stem seals. Any one verify that or suggest something else? Many thanks John

Reply to
John
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Typically on an in-line overhead valve engine that would be the case yes. On a boxer engine where the valves are horizontal the chance of this happening are slim.

J.

Reply to
P.J.Berg

What color is the smoke?

Reply to
John Stafford

VW aircooled boxers don't have valve stem seals, no need for them because of the horizontal orientation.

Then again, Porsche 911 has the same basic layout, AND valve stem seals, AND they often smoke at startup after sitting a while. Oil somehow collects in the cylinder, and since the cylinder is horizontal, the oil has no way out, gravity won't help.

Go figure.

On inline 4 cyl engines, smoking at startup could very well be intake valve stem seals. It would probably smoke under deceleration too, when the vacuum is highest in the intake manifold, pulling oil through the seals.

Reply to
Jan Andersson

Colur bluish, not the black smoke of being a bit rich. From the replies I dont think I,ll worry to much about it. It was actuallyon my T3 . Ta John

Reply to
John

Probably the rings, based on my admittedly limited experience. My

1600DP was doing that for a little while right after a top-end overhaul. Start it up..nice big blue cloud. Then it would clear right up and didn't smoke a bit while I was driving. It didn't do it every time, either.

When I tore it back down a few years later to fix an oil leak I found my mistake..the ring gaps were set too close together, and I guess sometimes the oil behind the scraper rings was able to pool at the bottom of the cylinder, resulting in that nice blue cloud on start-up. Once I followed the directions on the ring gap placement the problem went away....along with the oil leak :-)

My 88 Mitsu with the 2.6l engine had a problem with the valve stem seals, which was a common problem on that engine....I'm sure you've seen at least a few dodge caravans with the 2.6 blowing a blue trail around town. Anyway on that engine with that particular issue, it would not smoke on start-up, but leave it idling and it would start smoking. I guess the high manifold vacuum at idle was pulling the oil down the guides and into the combustion chamber.

Best,

Chris

Reply to
halatos

Thanks for that. Could well be the rings as engine is an untouched 1970, Wouldnt like to guess how many miles on her. Just seems to time it for maximum embarassment. Family waving you off get enveloped in a cloud of smoke, at registration check, that sort of thing. Your,re right, funny how reading the instructions helps!!. Interesting your comments on Mitsubishi,s. I,ve noticed that if ever I see a car blowing a bit of smoke it will almost always be a small capacity Mitsubishi. I,ve just got myself a spare T3 engine. May be about time to start rebuilding. Thanks for suggestions Gents John

Reply to
John

This can happen if you're parked on a left/right slope (one side of the quite a bit higher than the other). A little oil pooled in the 2 cylinders on the side with the head lower, and on the crankshaft side of the piston, has nowhere to drain except past the rings into the combustion chamber.

John

Reply to
John Henderson

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