Thanks for the replies. I have been going through the service records (fortunately, they were saved; of course, there could be a few "key" records missing) but
1) there are a LOT of service records, and
2) I am not a mechanic.
But, Michael, as far as I can tell, the head has never been off.
Here is what I HAVE found:
1) Techs have been noting an oil leak at oil level sensor and at rear main seal since early '98, about 50,000 miles ago.
2) Oil has been changed often.
3) Spark plugs seem to be replaced about every 3 months.
4) In '98, car came in with fluid leak R/F. Tech comments: "Due to over-heat condition". Oil leaks already present. R/F leak exists to this day, as my driveway will attest.
5) Splash guard under engine is missing.
Mike, please tell me more about the modulator valve.
Michael, I wonder why the MB tech didn't do the compression test? He did a cooling system pressure test, and R/R spark plugs to see if coolant was leaking into combustion chamber, and that's all. I know from driving it to the shop that there is a big gap between pressing the accelerator and the car actually moving, but I assumed it was mainly because of the 4000lb weight. (Remember, this is my first MB-- I really don't know how this wagon is supposed to take off).
The last service record I have is from 9-14-01. Think I'll call the tech, and see if he remembers anything.
Lastly, what about just replacing the engine? Any thoughts on that?
Thanks again guys,