Brian McL

I have a friends 1990 500SL for repair with a bad vacuum pump.

I removed the pump assembly and the smell of "burnt motor" was very strong.

I removed the motor and opened it to discover the motor pretty much melted down.

The windings were as black as could be.

Obviously the motor over heated to destruction but the question is why would it keep running to the point it self destruction.

I've look at a schematic and cannot see an accumulator tank that stores vacuum for the system.

I thought there could be a leak in the stored vacuum tank that the motor keeps turning on to top up......but I don't see a tank.

Is there one ?

If not why else would that motor stay on to the point of melting down?

Thanks for the help.