Could someone please confirm the function of the aux water pump. Is it actually a closed loop transfer pump i.e. just moving water around or is it a lift pump i.e. can pump water out of a glass into the sink. looking to repair one and would like to know how it's supposed to work. Thanks
Auxiliary Water Pump Funcitionality
1 - 20 of 167 Posts
The top of the pump is like an impeller. What is wrong with your pump, if it does not work it is most likely worn out brushes. These can be replaced by removeing base, drill hole in bottom and use fine wire to hold back new brushes while you put it back together. Then pull wires through hole.
Attachments
When I replaced my pump I used the occasion to refresh my coolant and let the reservoir completely drain empty. Used a hose to flush the dirt that had accumulated over the years out the reservoir, installed the new pump ($200) and added fresh MB coolant 50/50 mix with distilled water. Turned the key to #2 and the new pump sucked the air out of the system. After that I just checked for a couple of days the coolant level.
Good idea but after drinking the 2 bottles of wine I'll be in no shape to change the pump.
Mike
x2:thumbsup:
megaclamp
Mine died recently and I pick one up from the local salvage yard. I decided to test it and the working one could not pump water out of a bowl. so i was wondering how it worked. Also I took my old one apart and it looked just like your picture full of carbon dust. Will get some new brushes and repair and I will have a spare. Looks like these pumps are only good for about 60,000 miles or so.
Thanks for your reply.
Mine died recently and I pick one up from the local salvage yard. I decided to test it and the working one could not pump water out of a bowl. so i was wondering how it worked. Also I took my old one apart and it looked just like your picture full of carbon dust. Will get some new brushes and repair and I will have a spare. Looks like these pumps are only good for about 60,000 miles or so.
Thanks for your reply.
You may need to prime the pump before it will pump to a higher level. No problem in the actual application since it is lower than the reservoir and will always have fluid in the pump.
Mike
That would explain why I never have trouble with it now at 187K miles.
I never heard it working for past 57K miles (4 years) but occasionally after stoping I can hear bubbles moving up through the system. I've never had overheating problem even in hot summer days while pulling big trailer.
I do have extra oem (new) pump and hoses that I could replace it with.
How important is this pump, since I have it, should I change it?
I never heard it working for past 57K miles (4 years) but occasionally after stoping I can hear bubbles moving up through the system. I've never had overheating problem even in hot summer days while pulling big trailer.
I do have extra oem (new) pump and hoses that I could replace it with.
How important is this pump, since I have it, should I change it?
I think you missed Wiley's point; it was said tongue-in-cheek, meaning if it didn't have a purpose why do you think it was put there?
How do you know it's working? Or really, how do you know it's not working? Is it a Bosch part? I'm at 115k and their aux pump on my Audi failed at 54k. Are the brushes commonly available?
Sure would be sweet if someone posted where and what brushes to get. I guess I might give it a try. Although aren't some just corroded and not just brushes gone out?
Rocketman and Scott , I spent the better part of Sunday searching the web for the brushes. it appears that Bosch never intended for this pump to be a repairable because I could not fine any info. on one brush I found a reference of L47 but could not cross that to anything. I did a quick measure ( ruler ) and beleive the brushes are .187X.187X
.5 plan to mic it tonight to check those number. If that correct I think I have a sourch
and will post it as soon as I confirm.
.5 plan to mic it tonight to check those number. If that correct I think I have a sourch
and will post it as soon as I confirm.
The pump is computer controlled and runs at other times, not just when the engine is turned off for a couple of mins. If yours does not work you will hear gurgling. Thats the red hot air trapped in your engine trying to get out. The pump gets full of carbon which makes the brushes stick and won't move down the bore. By this time they need changing. You can use any brushes you find, just re-size them with sand paper they are quite soft, and solder the wire on. The tricky bit is getting the base of the pump on as the springs for the brushes with piss you off and break your new brushes. Thats why you need to drill hole in the base and use fine wire to hold the brushes back while you put the base back on, then pull the wire out through the hole. 43sqds the man for that tip thanks.
You are correct. Thanks for clarifying the pump's operation. The pump will also run when the climate controls are set to Residual heat and ventilation mode and will run for about a half hour, depending upon several conditions, when the key is turned off. I live in the north east and never use this function. Does anyone here use the Residual heat and ventilation mode?
However the primary function of the circulation pump is to alleviate the hot spots in the engine when it is initially shut down and this is when most people hear the pump running.
Mike
Scott and B7K here are the dimensions for the brushes, which should be braided back shunted (the end terminal of which does not matter because it has to be cut off). Contact Carbonbrush.com and ask for help in getting the closest one. Always choose the larger dimensions as they can be sanded.
Back- And Side-Shunted Brushes
4.928x4.928x19.685 mm
0,194x0.194x0.775 inches
13/64x13/64x25/32 fractional
1 - 20 of 167 Posts
