blue smoke on start up

Anonymous-0 · Jan 21, 2011

Hi guys,
I have a gas tractor that only seems to blow blue smoke at start up. It doesn't seem to burn oil by watching the dipstick while working. Is there anything in particular that would cause this other than the rings are going bad. It runs and starts great.

bg/mo · Jan 21, 2011

valve guides are leaking a bit, i wouldn"t worry bout it.

Allan in NE · Jan 21, 2011

Doggone it,

I sure wouldn't even worry about that. These old tractors were built with a lot of clearance in the guides and most didn't even incorporate stem seals.

What you are describing is pretty much normal to my way of thinkin'.

Allan

Mike M · Jan 21, 2011

You didn't just happen to switch to snythetic oil did you ? It will make this worse.

old · Jan 21, 2011

Valve guides/seas are leaking a little bit. What happens is when you shut it down the oil that is on the rocker arms etc. slowly runs down and into the cylinders. Only takes a couple drops to cause an engine to smoke on start up. Just think of it this way you never start your engine with dry cylinders and in the long run could well be good for it. My 1980 Chev pick up has done that since the day I got it and to me that is just fine and I'll leave it alone one of those if it isn't broke don't fix it things

JDemaris · Jan 21, 2011

If it's overhead valves, and it bugs you . . . you can put valve-seals in with a few hours work. No need to pull the engine all part. Put compressed air in the spark plugs holes, one by one, removed valve springs and stick in seals.

I've done too many to count, tractors, cars and trucks. SB Chevys had a big problem with valve-guide leakage 60s- 70s.

Jerry/MT · Jan 21, 2011

Valve seals and guides are worn. the oil drips down rom the rocker area after shutdown and burns on start up. If it"s a gasser, it may smoke at idle as the high vacuum sucks oil past the guides.

RandyB(MI) · Jan 21, 2011

Good accurate info from all below. Might add though , If it gets worse or starts smoking even when working , take off valve cover ( if ohv and not flathead , you didn't mention which it was) and check to make sure oil drain back holes are not clogged with sludge or broken up old valve seals. Happens a lot. Oil will fill up cover and when gets deep enough will suck down valve guides. This was a common problem with small block Chevys that never got warmed up or run with stuck open thermostats and also when the cheap "umbrella" seals would crumble and plug the holes.

blue smoke on start up

Anonymous-0

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bg/mo

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Allan in NE

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Mike M

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old

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JDemaris

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Jerry/MT

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RandyB(MI)

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