Hey guys!

I have a 1987 300SDL with the dreaded #14 cylinder head. The car ran great until this winter. I switched it over to synthetic oil and it slowly began smoking on cold starts. I wasn't too concerned because it would go away after a while.

Well, now it is spring and it has worsened over the winter. Now when I start her up it idles roughly for a little while, then after revving it up and driving for a few blocks she starts to calm down a bit, with the occasional misfire (from cylinder #6)

Further more, whenever I am driving it sounds like the engine is "knocking". Disconnecting the #6 injector seemed to quiet that down considerably...

Any ideas as to what could be causing the blue smoke on startup and the misfiring at idle? Once the car has been running for about 15 minutes she purrs like a kitten and runs real nice.

My theories are:
Valve stem seals need replacing
Turbo needs to be rebuild
Blown head gasket
Cracked head


I am really hoping it is the turbo or valve stem seals as those aren't TOO involved...and a blown head gasket wouldn't be completely terrible since I have a lift...just tedious...

Any ideas?