You should do a search on the subject. You'll find more info if you look under 124 chasis.

These are very stout/ reliable cars. Weak points are: the A/C has problems with the actuators that control the flow of air through the vents. You can tell there's a problem if little or no air is coming out the center vent but the defroster vent instead with the A/C on. They are also known to have a problem with the evaperator. Both are expensive to repair because you have to remove the entire dash.

Other weak points are the valve guides, not too expensive. I'm not sure is the years you mentioned have problems with the wiring harness. You can expect the radiator and water pump to need replacing around 110-120K (miles).

The most important thing is to be able to see the records from the cars history. If the things I mentioned have been done, you should be good to go for another 100K.

Good luck.

__________________
Mr. BILL

91 300E 120K
90 300SE 275K (sold)
92 BMW 525iM 120K
90 BMW 525iA 175K
85 300D 175K (sold)
84 300SD 245K (sold)