The 98-99 E300 turbo cars, in my opinion, are the worst of the W210 series. Much to my dismay, we sold our 1998 E300 thanks to it's status as a shop-seeking princess.
We had many problems, and many of them were unique to the Diesel driveline. Yes, we had glow plugs go bad and both crank seals. We had the MAS go south, and the final drive seals too. The ACC evaporator temp (one) went bad. And the list went on and on.
I have talked via internet to many other 98-99 E300 owners that curse their cars.
The upside is when the car was actually running that it was a hoot to drive. Terrific mileage and incredible range. We could easily make over 1000km's on a tank. The car handled better than any other diesel car EVER made, and had enough oomph (torque, baby!) to run with the E320 gas car and smoke more than a few unsuspecting folks.
Our smoke-silver/parchment car was handsome and attracted a few oohs-and-ahhs.
1998 C230 "Black Betty"