Hallo,
I own a Mercedes C220 from 93. No engine modifications. Just had a service with change of air inlet filter and spark plugs
(150' Km service)

The problem is as follows :

When the engine is hot (over 80 degrees Celsius, it seems) it will not start by using the starter motor. However if i roll it down a hill, it will start fairly easy (sometimes it takes 5 revs or so). The normal runnig temp for the engine is about 85-90 Degrees Celsius.

The start motor runs the engine sufficient fast to start it when cold (starts actually very easy, maybe after 1 or 2 revs) and dosn't seem slow, compared to other cars.

If I let the the engine cool down a little (about 20 mins), it starts immediately by using the start motor.

I would appreciate help from anyone who has an idea what causes the problem !

Thanks in advance !