Ldorris

Looking for what manifold vacuum should read on 2001 S600. Getting 15.5" hg... seems low

ItalianJoe1

That's low in general for a healthy engine but what issue are you having? Idle vacuum can be greatly affected by RPM.

Ldorris

It's idling at around 670 RPM. Issues are down on power, occasional misfires, and smoke from the tailpipe after 15 minutes or so (and lots of it under load... no smoke until it's warm). The PCV system was clogged, so i cleaned the passage in the cylinder head cover and ran all new breather hoses. Greatly improved things, but it's still not running right.

ItalianJoe1

Sounds mechanical, have you done a compression test? How do the plugs look, any saturated with oil? I'm not familiar with the M137 though so I'm afraid I won't be much help.

Ldorris

New plugs, coil packs seem good (thus only misfires sometimes, not consistently), new plug insulators, checked for head gasket leak with bubble gas test from radiator, new intake manifold gasket. Have not done a compression test, but not getting inconsistent or unusual puffing when i remove the oil filler cap.

kraut56

Look here:

https://mbworld.org/forums/s-class-w...ml#post7605154