Question about smoke on start up

[artpeck]

This is really just a question of curiosity more than anything else.

When I start the engine after the truck has sat for awhile, usually a week or more, I get whitish blue smoke that then goes away quickly. I am not burning any oil of significant as the level is dead solid. Compression and oil pressure are at spec etc so I am assuming that this is the result of a small amount of oil getting into the cylinders. Would this be via the valve stems? There is probably a simple answer I am missing and again there doesn't seem to be any issue associated with it but also curious if I should be concerned about something I am missing.

Thanks for the help.

[ybt502r]

White smoke ~ antifreeze
Blue/gray smoke ~ oil
Black smoke ~ fuel

This was taught to me, and it's seemed to hold up. Have you checked your radiator level?

[SafeAirOne]

I am assuming that this is the result of a small amount of oil getting into the cylinders. Would this be via the valve stems?

That'd be my guess.

[TeriAnn]

White smoke ~ antifreeze

If it goes away in about 15 minutes or less it is usually condensation within your exhaust system. If the air is moist water tends to condense inside your exhaust system. It gets ejected as steam as your exhaust system heats up next time. Especially visible on colder mornings.

If the white smoke doesn't go away it is likely coolant from a bad head gasket or cracked head.

Blue/gray smoke ~ oil

If your valve guides are worn a bit or if you have valve seals that are worn, oil from lubricating the valve train can flow down to the top of the valves. This is usually seen as a few seconds of gray smoke at start up then goes away. It is nothing to worry about and does not require immediate action. Just address the valve guide clearance during your next valve job and hope no green peace folks are looking at your truck at start up.

If you have blue/gray smoke all the time you likely have worn and or broken piston rings and a ring job & possibly larger size pistons are called for. This is a real polluter situation and should be addressed as soon as possible.

Black smoke ~ fuel

Sometimes seen if you over choke and engine at start up or forget to pull the choke in. Often times means you may be due for carb work. Check the float valve and float level after checking to make sure the choke is OK.

[artpeck]

Thanks all. Appreciate the advice and knowledge. My radiator is fine and level hasnt changed. Appreciate the advice in the choke and carb. I have to choke the engine on every start up until it warms and have been meaning to work on the carb but haven't had the time to get on it. Sounds like it has risen to the top of the list.

[singingcamel]

Valve seals is my guess

[TedW]

Valve seals is my guess

Yup. X2

[Billy5]

Mine does the same thing. Stranger still is that it will only do it once in a while, after a short trip but only once. I can smell it, and it is oil. Does the exhaust smell " sweet"? If it does then its antifreeze.

[artpeck]

It is definitely oil. And only happens after the truck has been sitting for several days. And never burns oil after the first minute or so of running at the most which makes me pretty sure that it is seeping in while at rest.

It is also a very low mileage engine in the scheme of things as i bought it from the original owner who bought it new in 1972. His teenaged son drove it to school and back and as soon as he left for college it was stored and never driven since. Less than 30k on the clock.

[Billy5]

I would say valve stem seals. Mine is lower milage too. Letting them sit isnt good I dont think. I use mine as a dd so for a truck thats been sitting/hardly used, I would imagine seals would not stand up. From what I understand, the seals are not the bad to replace.