Is a worn dipstick o-ring like a vacuum leak?
 

Last time I checked the oil I noticed the dipstick in this '95 E320 didn't fit snug in the tube. Would that feel the same as a vacuum leak? i.e. not as smooth idle as I'd expect some times.

Nice Try ! [Gloming onto that Thought process,It wopuld be the exact opposite.]
 

(DISCLAIMER: I know [And want to know even less] NOTHING about Gasoline/Petrol/Benzine Mercedes.)

The Engine Oil (Sump) Dipstick has a nice little rubber "O" ring to seal the Tube
AGAINST acquiring and Dust, DIRT, or other Contamination.
If the "O" ring is Old,Dry and Brittle and has Shrunk from it's original Thickness;
it MAY allow SOME Crankcase Gasses and Pressure to vent through the no longer sealed "DipStick" tube.

[REMEMBER the DISCLAIMER ? Mercedes COULD have some Extreme Walter Mitty
device that senses loss of "Blowby" and corrects for it through Electronic Wizardry (?)]
[Although, WHY they would do such a thing would not be able to be explainable in the Physical Universe we inhabit!]

I know on some BMW's if you remove the oil cap the engine runs rough.

Yeah,So... (Application, Here?)
 

BMW Makes wunnerful:
Marine Engines
Aero Engines
Motorcycles

The 4 wheel conveyances they claim are automobiles are Excrement!

[Except the Mini , of course]

How Much can the "O" RIng cost @ a Stealership?
 

YOU have just volunteered as an Official Testbed Mercedes Owner!

'Run ovah Thear and pick up a New "o" ring and see if your idle smooths out.

Yes Sir. Immediatly Sir.

won't make a difference other than making the dipstick a little harder to get out.

No vac in underside of engine.Theres wind from crankshaft and blow by if pistons are worn.I replaced my dipstick o ring as full pedal would blow oil over motor.

No, it's for sure a vacuum leak and you need to fix it.

I've seen these motors simply stop running when the dipstick is pulled.

Well now, that clears it up.

lol :rolleyes:

:no:

no blowby? Leave it alone. Check elsewhere.