Can the motor portion on an auxillary water pump be rebuilt? Can you just by-pass the pump? I dont have any heat in my car?

From what I have dealt with, and others I have read about, the problem is probably the monovalve and not the aux. pump if you have no heat. There is a rebuild kit for the monovalve and takes all of 15 min. to repair.

The aux pump usually shows up as weak heat especially at idle. (I believe Carrameow had a write up with pics on rebuild.) I don't think the motor is available separately though. An advanced search will turn up more.

Also, note that these are both controlled by the ACC controller. Bad solder joints in the controller can give you the same problem. (It is hard to believe that folks are complaining about no heat. )

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Sam

84 300SD 350K+ miles ( Blue Belle )

Mike,

Connect 12 volts to the aux. motor and see if it runs. That will tell U wether it is the motor or something else not working.

P E H

I agree, no heat is usually due to the monovalve or the CCU. I had a semi-broken CCU for a while and the aux. pump didn't work, I still had plenty of heat while driving. When I replaced the CCU, the aux. pump started working again. The aux. pump only makes a real difference at idle.

How do you determine if it's broke? Can they be rebuilt? Where do you get one at a reasonble price?

If you remove the connector from the motor (the connector pulls apart -- carefully!) and wire the motor directly to the battery, you should be able to hear the motor running (polarity doesn't matter for this test only). If you get sparks but no sound, the motor is frozen. If you get no sparks and no sound, the internal wiring is open.

If the motor runs, the problem is likely the ACC, as has been said, or the monovalve. Both are repairable or replaceable. Lots of information here, do a search for "acc" and/or "monovalve."

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

If you have full heat with the defroster but nothing with the panel switches, could the axillary pump be bad? That doesn't seem possible but a garage just charged me $280 part and installation on top of the new panel ($875 plus 180 labor). I think I was raped? Before I go in and raise hell (always pay with plastic!) I need to be sure about the aux pump; does the defroster require it working? If so, then mine WAS good after all!
Thanks, George near Seattle

Especially when people post links to that foul place (mercedes$ource) to buy junk.

Rather than blowing $75+ on a pump, replace it with a tube. The pump is a waste of money, you'll get plenty of heat without it.

Coffee hadn't yet kicked in this morning.

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1979 300D 275K

http://www.peachparts.com/shopforum/showthread.php?t=112575&highlight=pump

Was I deleted? Still learning the rules here.

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1979 300D 275K

Whenever I see a Mercedes in a junkyard I pull the pump. If the impeller turns freely with a small screwdriver or pick, it's probably good. I keep a clean spare in the shop.

Lots of cars use these, VR6s used them, Audis used them, look for the correct hose size and you'll have to graft the M-B electrical connector on.

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Gone to the dark side

- Jeff

If the pump is forced to run without the heat on, will the coolant flow or will the pump be strained?

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Monovalve works this way - 12volt actuates the plunger to stop the coolant flow
0 volt retracts the plunger ( spring return ) and you have heat.
Since you have no heat then it may be the plunger is stuck and cannot retract. Measure the voltage across the monovalve when you call for heat. It should be 0v. If you see 12v than the climate control is faulty. If you call for A/C then the voltage should be 12v.

The aux pump may be faulty but I doubt it. You can check it with battery to see whether it spins as suggested by other member. You can wire the aux pump to be on all the time whenever ignition is on. It probably will not burn out the pump but it would be a last resort for me.

As for a new CCU, it is a lot of money and you can get a better deal from a junk yard as there is a lot of junk gas MBZ.

Good luck.

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Not MBZ nor A/C trained professional but a die-hard DIY and green engineer. Use the info at your own peril. Picked up 2 Infractions because of disagreements. NOW reversed.

W124 Keyless remote, PM for details. http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/334620-fs-w124-chasis-keyless-remote-%2450-shipped.html

1 X 2006 CDI
1 x 87 300SDL
1 x 87 300D
1 x 87 300TDT wagon
1 x 83 300D
1 x 84 190D ( 5 sp ) - All R134 converted + keyless entry.

I've read here somewhere that a bad pump can also fry the CCU.

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DJ


84 300D Turbodiesel 190K with 4 speed manual sold in 03/2012