Gentleman I need some ideas. My 81 380SEL has had both heads redone to include valve guide seals and new oil tubes, but I'm still getting blue smoke out the exhaust when I coast down hill and imediately after I accelerate. Whats' puzzeling is that from a stop no smoke appears. Oil consumption has improved but its' still using. Any suggestions? Head bolts were a cause of lost compression but have been retourqed. The car runs great but the smoke is driving me crazy.

Blue smoke = oil burning. How old are the rings?

Blue smoke
 

Glad someone is interested. I don't know about the rings as far as age is concerned, but have checked the plugs for oil residue and have found none. If the rings were the problem wouldn't the somke be vsible all the time instead of at deceleration?

Not necessarily. Engine vacuum is strongest during deceleration. Valve seals would show up as blue smoke upon startup. Worn oil-control rings cause what you are seeing.

I would try a compression test and leak-down test. See if compression is holding up, or maybe the culprit is just one slug out of the bunch.

In any event, I would plan on a ring job and while you're doin the bottom end, all the crank & rod bearings and motor seals.

Anyone agree?

I would say that unless it is pretty bad and you were using a terrible amount of oil, keep putting oil in it. Oil is way cheaper than tearing down an MB engine.

Isn't it possible that an oil control ring could be bad, but the compression rings still good? I mean a compression test may not show oil control ring failure, or would it? Just guessing here. Any opinions on that topic?

Thats as good point Q. Do ya think that some ape over-torqued the head studs and maybe pulled up some metal and warped the block deck, so that maybe one of the oil galleys is leaking?

Blue Smoke
 

Q and John, thanks for your input. I will be unavailable for a few days but will take your advice into consideration and explore my options. In the meantime any more suggestions are greatly appreciated.