Hi, I've noticed that the washer bottle is always really hot, even on a hot day. It seems there is an electric control valve/servo for it, on the passenger side next to the firewall, presumably this valve is always open. The line coming off of this valve also seems to go to the heater valve on the inside side of the firewall.

I'm concerned because I've already broke one of my washer pumps (for the headlights), I'm thinking now that because the bottle was always hot it caused the plastics to get brittle over time and crack.

I haven't been able (yet) to locate any information on these parts yet and what determines when this valve is open or closed. Does anyone know how this part of the heating system is supposed to work?

'91 300E 205000 mi.
Purchased, 9/2002, 178000mi. DIY repairs: brakes (caliper ceased), water pump (leaking), EHA (leaking), brakes (pads gone), mufflers (broke off), radio (draining battery), warning buzzer (fried circuit), steering linkage (ball joints gone).

Thanks for the tip, I see what you are talking about. Looks like I'd have to replace the whole assembly ($137) or maybe there is a chance I could fix it myself, if its possible to disassemble and clean.

Wally - before you disconnect, discard, etc. I suggest you search this forum for postings by others who have experienced your problem. I can remember at least three threads. Bottom line is that part #126 830 07 84 or similar is certainly available from dealer (I paid under $35) or cheaper from Phil at Fast Lane. That part attaches to the end of the stainless coil and acts like a thermostat admitting or blocking the flow of bypassed coolant.