I'm tuning up the old and she's been sitting for a while ('75 450SL).

When she gets up to operating temp the idle drops to about 500rpms & she starts to smoke. I didn't have her running that long hot, so I don't know if it was oil or fuel smoke, but it was definitely darker & not H2O smoke.

Any idea what would be the root ot of such a system after warm up? My old 380SL used to smoke UNTIL it warmed up due to bad valve guide seals, but AFTER warm up?

Thanks!

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Currently:
1972 350SL Euro 4spd
1973 BMW R75/5
1981 BMW R80GS
1995 FZJ80 with OM606 Conversion In Progress