Auxilary Water Pump Not Spinning! - PeachParts Mercedes-Benz Forum

slimak9 · #1 03-14-2006, 11:16 PM

I get very low heat when I'm idling, and its gets better as I begin driving faster than 10mph. (I figured it must be the Aux Water Pump).

Today I was flushin my Rad and decided to install my new Aux. Water Pump, I did so, and no difference was achieved. I then noticed that the pump is not spinning. Neither the new or old pump spin, which concludes that there is no power going to my Aux Water Pump.

I have the car runnning at approx. 85 degrees C, and have the Climate Control set to Max Fan W/ Heat on Defrost.

Anyone have an idea where to check the electrical connections or wires? I also recently installed a rebuilt Climate Control Pushbutton, and the heat has been the same with both the new and the old. (So it may be safe to eliminate the pushbutton unit as the problem for not giving the power to the Aux Water Pump)

Thanks for the help.

slimak9 · #2 03-14-2006, 11:18 PM

Its a 1987 w124 300D Turbo.

Thanks.

whunter · #3 03-15-2006, 02:15 AM

Test for voltage at the pump and mono valve, report results please.

You may want to try flow testing (with a garden hose) through the heater core only, if the output is low = plugged a plugged core.

joel · #4 03-15-2006, 02:19 AM

also check fuse, if you have not done so.

Richard Wooldridge · #5 03-15-2006, 02:46 AM

I'm not sure on your car, but the climate control on the 107 chassis has three separate fuses, so it's possible that the aux water pump fuse could be blown and the blower fan still operate. On the 107 chassis, fuse 7 is the one for the aux water pump. Sorry, only have the 107 factory manual.

slimak9 · #6 03-15-2006, 02:25 PM

whunter:
I found 0V at the Aux Water Pump at Def.

But then

I found a cut in one of the wires. Soldered it, and now get 12.45V. Thanks for the advise.

Funny that I connected the old Aux Water Pump and it wouldn't spin. Is it possible that the old pump siezed and fried the wire??? (If so, good thing it did so in a visible spot, not in the joy of the fuse box.)

The voltage at the Mono Valve is 11.87V in Off & 1.23V in Def.
The resistance is 13.7 Ohms. (Which as per Mercedes Manual should be between 11 - 19 Ohms.)

THANKS AGAIN!