I own a 6 cyl 1991 300-SEL.

The 90-91 models have a MAS controller - silver metal box a bit larger than a pack of cigarettes that plugs in near the fire wall. This unit has a fair amt. of integrated circuitry that was more segregated in the 88-89 models.

The problem is if ANY one function goes out in that box, you replace it and last time I looked it was pushing $600 @ the dealerships. You can buy a replacement from the WEB sellers for less, but those are not new units. Some claim to have opened and repaired these and if your electronic repair skills are above avg., I suppose this could be done.

There has also been a lot of discussion here about a valve guide upgrade ocurring sometime in 88/89 in the M103 motor. I'm not clear on exactly when it occurred, but it does not matter. My '91 M103 motor uses oil just as all of them seem to, irrespective of any sort of valve guide upgrade.

Your post queries a specific MB model, but there are several engine configurations within the W126 line for the 88-91 period.

I've mentioned a few things for the small motor W126; I'm sure there will be more input from others who also own my model and from the V8 crowd.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"