Part question. - PeachParts Mercedes-Benz Forum

hightide · #1 03-29-2003, 01:21 PM

I own a 98 ml320 and have a question about a part.
I don't know what this part is called, I guess it could be described as a circulator pump for the heater. It's located near the battery, attached to the wall in the engine compartment. It has a couple of hoses attached to it, one runs thru the firewall into the cabin.
The thing is squealing like a wounded animal and it's driving me nuts. It's easy to get to, looks like something I could do.
My question is: "What is this part called?",
"How much does it cost?" and
"What's a fair price for parts and labor?"
Thanks.

tabo · #2 03-29-2003, 03:44 PM

is it the water pump?

hightide · #3 03-29-2003, 04:15 PM

No... it's this little "do-jigger" that's attached to the firewall, just under and a little forward of the battery. I know where a water pump is and this is not one.
It has a few narrow hoses running into, and out of it. One of the hoses runs into the passenger compartment. I am assuming it's some sort of water circulator. Just trying to figure out the name of it so I could find the cost for repair.

tabo · #4 03-29-2003, 04:47 PM

is that for the airconditioning?

hightide · #5 03-29-2003, 04:52 PM

I believe it circulates the engine coolant into the cabin heater.
It continues to run for a few minutes when the car is turned off.

Bayer · #6 03-30-2003, 02:34 AM

Is it attached to the body, or hanging next to the battery?

The only two things that I know of that continue to run after the engine is off is the aux water pump and the e-box fan.

The aux water pump is by the battery and continues to pump some coolant around after the engine stops.

That may be what you are hearing.

The E-box fan is in the bottom of the electrical box on the drivers’ side of the engine compartment. It is in the very bottom of the box.

Both the aux water pump and the e-box fan are on the same circuit and run for up to 5 minutes after the engine stops.

Hope this helps.

Gilly · #7 03-30-2003, 08:36 AM

It's called the auxillary water pump. The pumps purpose is to 1. provide coolant flow through the heater core (all modern Mercedes have this pump for this reason) and 2. to give coolant flow through the cooling system for 5 minutes after engine shutdown to prevent what engineers refer to as "hot-spotting" of the engine block.

We have replaced a few of these pumps for the noise concern.

Gilly