A170 won't crank when warm

[Clive]

My A170 diesel starts on the button when cold but is dead as a doornail when warm. Sometimes you hear a click when you turn the key

[Hymie]

It could be many things causing the fault � clearly something does not function as it should, once warm.

My bet would be on the starter motor solenoid becoming jammed and not making contact from the battery + to the starter motor.
Other possibilities include a poor electrical contact or the electronics/computer unit controlling starting the car.

Unfortunately it could turn into an expensive repair, as the garage changes parts randomly, in an attempt to fix the problem.

[gonzo00]

i have had this prob with a merc vito van...turned out to be a relay somewhere but don't know which one as it was the dealership that fixed it under warranty.