So i replaced my ailing starter on the 240d with one from my parts car.
The starter works fine. The only problem is, immediately after the car fires up i hear a little groaning sound coming from the starter.
any ideas?

sounds like a bad bendix.

the gear is probably staying engaged after the engine fires.

i think you may be able to find a kit to rebuild it.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Might be able to swap the drive from your old starter over to it. Could be just no lubrication present or hanging up a little on rust. At least the starter mount bolts are removable right now without too much effort. You also might drive it for a few days to see if the current use after sitting clears the problem. As long as it is not staying engaged too long.