fredweet

2003 ML350. The auxillary water pump is not working anymore. Today I had the hood open and checked it. I tapped the motor and it seemed to rotate a bit and then stop again and start and slowly stop (feeling by the vibrations). I think it is dead. Is there anywere I should look for a new one? any suggestions? Maybe I should take it off first and check it out to see what the prob is?
Thanks

wildzeus

My pump went out "again" today. Again as in I have installed 3 used pumps from a salvage yard. The 3 pumps averaged only about 3 days of life. I have given up using the used pumps - buy a new one from MB!

fredweet

I looked online and I found the auxilary pyump for $366 canadian$ - crazy. Then I looked further and found one for a 1993 190E which looks the same except for the connector. Do you think either part would be run by 12volts so they may be interchangable except for the connector. I have to call my local suppiers around for the part though to see if they have it.

sosh

Any dealer would have the correct pump. I would not use one that is not specifically for your ML. Also you should note that junk yards are not a credible Mercedes parts source.

fredweet

Well I got a new auxillary water pump in the ML.
What I did was a lot of researching. Found out that the VW Jetta 1.8T uses a pump just like it made also by Bosch to cool the turbo - it looks identical. The connector is the same bosch style, and the wiring the same thickness, The in and outlet on the Jetta version is slightly bigger but only by like a mm. So considering the MB dealer wanted $423 CAD and I ended up paying $107 for the VW I saved a lot of money. It takes litteraly 4 minutes to install.
So I am happy
Fred

tonyML

Hi Fred,

Do you have the part number for the pump from VW?

My was out also.

TIA

Tony

Darkmann

That's about the same cost in the US. Mine was done for near $US 400, but that also included a complete coolant flush.

vonzipper

Try Looking at 078-965-561 dont know if it fits, I'll fill you in tomorrow

jack shiny321

its so nice to visit here a nice thread. Am so impressed with your such a good hard work, its definitely a good and diferent idea for others, you guys are doing good work good luck, keep it up..

gregvolt

ok so I'm a year late responding to this thread but i took fredweet's advice and went for the volkswagon pump. drained my antifreeze and changed the motor. works perfectly. had to push the hoses on pretty good since the hose inlets are slightly larger than the original MB pump. after i changed it i wanted to see what the problem was on the original pump so i disassembled it and found that the brushes inside shifted and burned but that is not what i found the most interesting. when i was disassembling it i first unscrewed the top 4 screws and took the pump section off.
that top plastic piece is a sealed pump unit and it works magnetically when the motor moves the magnet around it. so what i did was take the pump part outside to the car and compare the configuration of screw holes.. they are the same. so although i didnt try it because it was already installed and i refilled the antifreeze. i believe you can save yourself some work .. just unscrew the upper black plastic pump part from both the old and new motor without disconnecting the hoses and change the motor underneath the existing pump in the car and put the 4 screws back. the pump part itself is sealed so theres nothing electrical to wear out or burn out so i cant see it being a big deal if you use your old one.

Roderic B

Quote From Gregvolt.

That top plastic piece is a sealed pump unit and it works magnetically when the motor moves the magnet around it. so what i did was take the pump part outside to the car and compare the configuration of screw holes.. they are the same. End of Quote.

i bought the vw pump took the 4 screws out and guess what, there is actually
a reason why the MB pump is more expensive. As Gregvolt noted the original
pump is sealed and works magnetically. The vw isn t
when you look inside, you just have the impeller and a rubber seal, which means if the seal goes bad you will have an antifreeze leak.
I just installed the vw pump and it is working fine. I am happy it did cost a lot
less, but i am also happy to confirm we are not just paying the brand on parts,
when and if we buy the original, we are getting a better technology.

I want to thank everyone for their contributions on this and all other topics.
you have been very helpful in helping me deal with the maintenance of my ML350

Roderic B

after i saw a photo of an original Mb pump taken apart , i open d up mine again and realized that you can indeed separate the housing of the impeller from the top part of the pump were the connectors for the hoses are. my mistake, it seemed as it was sealed, which is what people are expecting i guess, when they only want to remove the 4 screws and change the bottom part of the pump while leaving the upper part connected to the hoses. If the impeller housing separates during the procedure there will be coolant leak...
Unfortunately the VW pump is already installed on the ML so i cannot open it again to check whether in that case when i removed the 4 screws the impeller stayed on the bottom part of the pump making me think it was a different technology.
Somebody in another forum states Bosch Vw and Mb original do have the same technology.
Should have double checked before making a commentary. i will in the future.