Our '91 300E just turned 200k and no valve job. I did recently discover the front cover seal is leaking.
I can't tell you why it doesn't need a valve job except that I bought it used a couple of years ago and it was very clear it was well maintained. A previous owner maintained through 124k miles at a dealership. It is without a doubt one the best cars I have ever owned. It looks great and really runs well.
I think the keys to avoiding the valve job are the following:
-Frequent oil and MBZ filter changes appropriate to kind of driving.
-Use quality oil of the right viscosity.
-Driving off conservatively until the engine warms, especially after sitting a while.
-Avoiding over heating at all costs.
-Drive it very hard occasionally, going into high RPMs until close to redline, only after warmed up)
I would pull my car off the road if I saw smoke coming out the tail pipe. Often it seems it is oil consumption not smoking that makes people do a valve job, and typically coming first from valve guide seals, then worn valve guides and then and a distant last, bad or worn valves.
I believe I read on this forum that in the year 1990 MBZ changed the valve guides and the valve guide seals, which are longer lasting.
Do you think your engine is due?
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)