Aux water pump leaking---W123 - PeachParts Mercedes-Benz Forum

Flyin4now · #1 03-11-2008, 01:17 PM

OK, I've tried to seach the archives. I cannot find much info on this aux water pump. Mine is leaking coolant (not much, but enough to leave a small puddle after shut down). I would like to disable/bypass it. Do I need to use a metal tube? Also, will disconnecting the electrical wires disrupt any functions of the CCU?
Thanks

#2 03-11-2008, 01:34 PM

You can unplug and bypass it without affecting anything, but they a re pretty easy/cheap to replace.

MB-Owner-in-ind · #3 03-11-2008, 03:19 PM

You can bypass it and use metal because it can withstand the heat, don't ask me how I know.

mobetta · #4 03-11-2008, 10:00 PM

I have a good spare available..........PM me.

or just bypass it.

3/4 PEX fittings fit 5/8 heater hose really well...

Flyin4now · #5 03-12-2008, 03:00 AM

Pretty cheap, as in how much? I found the pumps to be pretty pricey, so far

#6 03-12-2008, 03:34 AM

Bypass it. It was useful back in the EVIL servo days but its pretty useless with the ACC, there is plenty of natural flow through the system.

#7 03-12-2008, 08:36 AM

Quote:

Originally Posted by Flyin4now

Pretty cheap, as in how much? I found the pumps to be pretty pricey, so far

I replaced one a few weeks ago (it was starting to make noise), I think it was a couple $100 (I had bought it on-line a while ago). In my car it made a difference at idle. When mine didn't work previously (due to a CCU issue), I could feel the difference in the temperature when I stopped at a red light. It didn't get cold, but I could feel the change and it was annoying.

Edit: Here it is for $164, it's a little cheaper than I remembered:

http://catalog.worldpac.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1CQ0J3JZ42BK0IHE4W&year=1985&make=MB&model=300-DT-001&category=All&part=Auxiliary+Water+Pump

Dee8go · #8 03-12-2008, 08:47 AM

123's have an auxillary water pump? Do all of them have this? Where is it?

#9 03-12-2008, 08:50 AM

The turbos (with climate control) have them AFAIK, my 240D does not. On the 300D it's located in the heater hose on the right front of the engine (above the alternator).

vstech · #10 03-12-2008, 09:49 AM

Quote:

Originally Posted by Dee8go

123's have an auxillary water pump? Do all of them have this? Where is it?

my 78 parts car, 79 wagon, and 80 wagon all have the pump just behind the right headlight on the fender. the evil servo is just in front of it.

tobybul · #11 03-12-2008, 11:23 AM

Only thing is if you bypass it you will get heat all the time. I have an old thread with a picture showing how I bypassed it with copper pipe. I'll try to look for it and post it here. Otherwise, you can search for it.

I too have a spare but I don't know if I want to part with it.

I found it.....

Jadavis · #12 03-12-2008, 11:29 AM

Quote:

Originally Posted by tobybul

Only thing is if you bypass it you will get heat all the time.

Last time I checked the Mono valve controls WHEN you have heat. The pump just provides the flow. It is only needed at low engine RPM. At just about anything above idle the main water pump provides plenty of pressure.

-Jim

mobetta · #13 03-12-2008, 11:43 AM

Quote:

Originally Posted by tobybul

Only thing is if you bypass it you will get heat all the time. I have an old thread with a picture showing how I bypassed it with copper pipe. I'll try to look for it and post it here. Otherwise, you can search for it.

I too have a spare but I don't know if I want to part with it.

I found it.....

That' s the mono valve..........

#14 03-12-2008, 11:56 AM

Quote:

Originally Posted by Jadavis

Last time I checked the Mono valve controls WHEN you have heat. The pump just provides the flow. It is only needed at low engine RPM. At just about anything above idle the main water pump provides plenty of pressure.

-Jim

That's correct, and you don't want to by-pass the monovalve unless you live in Antarctica.

aaronkobi · #15 03-12-2008, 04:13 PM

Quote:

Originally Posted by Flyin4now

Pretty cheap, as in how much? I found the pumps to be pretty pricey, so far

I just picked one up for $80 from www.***************. Unplugged the old one, clamped the hoses, and replaced it with the new one. Took an hour and didn't lose much coolant (put a rag under where you're working to soak up some of the antifreeze that spills). The thing that holds the pump is just rubber. Wiggle the old pump forward (toward the back of the car) and it will just slide out.