Hello all!

I have a 1987 300d (m603 engine) that has, over the past few months, smokes a little bit at startup. The smoke is blue and does not smell like diesel, also the cooling system is 100% sealed, no leaks.

After research, it seems that the smoke is due to one of three things...1) worn piston rings, 2) worn turbo seals, 3) worn valve stem seals. I have done some investigating, and I would like your feedback. The car does not use very much oil, less than 1qt per 3000 miles (this is not a scientific estimate, and I will do a more accurate measure here shortly)

The blue smoke is only when starting the car, or after the car has sat for 45 minutes, also the smoke is not a giant cloud, not at all. When the car is at operating temps, there is no smoke (rules out piston rings?). Also, I called my Indy and he doesn't think piston rings, as the car had perfect compression when tested when I bought the car (4yrs), has had oil changed religiously, and does not suffer from any power issues (starts smooth and solid, though I hav e an afterglow mod, and does 0-60 in 10 sec). The Indy even said he did not recommended another compression test, as I have no symptoms of poor compression.

Next would be turbo. I removed the intake pipe from the compressor side of the turbo and found a little bit of oil, but not even close to a lot. I tested the compressor wheel/turbine for play and found none. No play up and down, side to side, and no play in and out. I had a hard time removing the exhaust pipe from the exhaust side of the turbo, so I did not investigate that. However, with absolutely no play in the turbine, could I rule out leaking turbo seals?

This leaves the valve stem seals, though I have no idea how to check for that. Any help or thoughts are greatly appreciates. The car runs great, I have put work into it, no would love to drive it past 300,000! (220,000 miles on the car now.). Here is a link to the video I shot on a cold, rainy morning.


Thank you for any and all help!!!! Just want to know what is exactly wrong