Reinstalling auxiliary water pump - question
 

I'm reinstalling the auxiliary water pump in the 1991 560SEL. A small approx 2" coolant hose connects the auxiliary water pump to a connector on the far left side of the fire wall. I'm thinking of wrapping the hose with heat resistant tape (such as used on mufflers and exhaust systems) then attach the electrical wire using a standard cable tie. Any chance the heat resistant tape could negatively impact the coolant hose?

Certainly unlikely, the hoses seem to be made of flexible kryptonite. My '91 still has the original ones everywhere except main radiator hoses.
One comment on the pump; if the motor drags a bit and draws a bit too much current, it will make the AC system go bonkers. Seems the system checks the pump motor periodically, even when it's not needed. If it senses too much current, it will turn the motor off, and open the monovalve and heater flaps fully for about 10 seconds, trying to overcome what it sees as a faulty pump, even though it's not needed. You get really hot air, then the system reacts and switches to full cold to get back to normal. A few minutes later, it does it all again. This tip came from the 126 pro mechanic at the local dealer, when I couldn't troubleshoot the symptoms. Disconnecting the pump motor permanently (Dallas) solved the problem. Seems earlier models could blow the AC controller when the motor started to drag, and this Band-Aid was the solution. Just a bit of trivia; but if it happens, you'll know.

DG