I have a 1991 300D 2.5 with 142k mi.
Maintenance and repairs have been
minimal considering the miles.
The 2.5 turbo is quick for a diesel,
and it gets 30+ mpg. The turbo kicks
in at about 2200 rpm. I am pleased
with the performance.
In 80k mi., I have replaced:
flex discs, fuel return lines, plastic
lines to overboost protection, motor mounts,
coolant level sensor, shocks & struts, glow
plugs, and v-belt, plus maintenance items
such as brakes, tires, & filters.
Check the following link to another
300D 2.5 owner's maintenance and repair
Have the climate control system checked.
Some w124s have problems in this area.
This engine has an aluminum head.
I have never heard of any head or
head gasket problems with the
602.962 engine. Above, MBenz
discussed head and head gasket
problems with the euro diesels.
I appreciate his experience, and
I am curious why we have not had
similar problems with the 902.962
engine in the US.
Watch for problems with the
plastic radiator neck in the w124's,
which tends to crack. Replacement
radiators have a metal reinforcement
sleeve. Overheating could cause
problems with the aluminum head.