blue/white smoke on cold start-up '90 560SEL
 

Hey guys:

Question: when my 560SEL is cold, it requires a few cranks before it kicks over, and has a resulting cloud of blue/white smoke that quickly dissipates after ignition. The car runs a little rough for five or ten minutes until it warms up, typically with a little rough and lowish idle. The car then runs pretty smooth and nice, and when it's warmed up, it doesn't have the smoke/hard start issue at all.

I am certain y'all will have a good idea what is causing this; thanks in advance for ideas I can troubleshoot.

could be valve seals wore

Valve stem seals.

Are you SURE that it's not blue smoke? If it is blue smoke then it almost has to be valve guides/seals. If it really is white smoke, smell of it to make sure it doesn't smell like antifreeze.

thanks guys. the smell reminds me a lot of the smell of the exhaust from an outboard boat engine. I assumed at first that that meant the engine was flooded with fuel, as that always seemed to be the problem with our outboard. The smoke looks similar to that as well, come to think of it.

I don't think it smells like coolant, though.

hmmmm. what kind of cost are we talking about for a valve stem seal repair?

anything else that should be done at the same time?

My first thought was a bad cold start injector. But I do not know at what temps that kicks in, unless its always used to start. I really dont know.

It would be a lot cheaper to have them done without the head being removed.

This would mean finding a shop willing to do "the air compressor trick" where you hook up a a air compressor hose (with a home made adapter) to the spark plug hole to keep the cyl pressurized and the valve in place while the spring is removed and the seal is changed out.

thanks for the responses guys. BTW, where's the cold start injector so I can troubleshoot that?

It probably smells like outboard gas because of the oil. Outboards used to be two strokes requiring oil mixed with the gas.

If it does turn out to be valve seals and it's not consuming an extremely excessive amount of oil, it won't hurt anything to run it for awhile before doing a thorough valve job.

good point. I'm glad to hear it won't hurt anything to wait (the oil consumption does not appear to be excessive); it's getting a little cold here (this is where the folks in the great white north can roll their eyes:). I wasn't looking forward to working on this in the cold!