auxiliary water pump rebuild W116 and others.

['79 Super Turtle]

I had my auxiliary water pump quit working on me. I have been freezing at idle for several months. I decided that since it was broken, I would take it apart and see what's what.

I researched quite thoroughly before for a fix, or rebuild kit. No luck with either. The option seemed to be replace it ($100ish) or ignore it. I had already unplugged it, so it would not fry my ACC board.

Here is what I did:

I removed it from the car, undid the 4 screws holding the cap on, this cap has an o-ring in it that is very important. It was impossible to find a replacement the right size, but the Dealer said they have metric o'rings, so I know it is possible to replace it. Mine was still sealing fine. If it leaks, it leaks out of the pump, not into the motor.

I have now exposed the impeller. It is next to be removed. It is just pushed onto a splined shaft, so in order to remove it, put the pump in a vise, using two sets of pliers, grasp opposing blades, and pull hard. It will come off quite easily, but you may end up against the wall.

Next remove the spring, plastic bushing, and the impeller housing (2 screws). Under the housing is another o-ring which keeps the coolant in the impeller housing and out of the motor.

Now we have to take the cover off of the motor, to access the brushes. This was the hardest part, because the three crimps are microscopic, and bending the tabs back up took a little tool ingenuity. Cover is off, brushes are in sight, and the trouble has become obvious. Worn brushes. They are not held in with the usual spring, they are clipped in, the wires are not soldered, just twisted and held in a ferrule.

I searched high and low, at all the best bets for carbon brushes, I saw every size shape and color, but not a no. 35 with a lead. The best part is that the first place I looked was at True Value Hardware, in the nuts and bolts aisle. They actually had three boxes of brushes, but none like mine. I returned at the end of my search (who knew the first place I tried would end up being the best) and I bought the closest size, went home and filed them down to the exact size I needed, and removed the spring.

I was pretty psyched when I touched the motor to the battery and it spun away! So I have heat(too much!!!), and the whole thing cost about $5.00!



Patsy

Go to the fast lane catalog and type in the search by part number feild 0005860583 sells for 37.20 is this what you have been looking for ?

['79 Super Turtle]

Thanks Dr., do you know if the pump in the '79 300SD is the same as the pump in the '81? I have read many discouraging posts about the kit not being the correct one for my year. I also don't get a result for my year at the FastLane, but I do for the '81. If I ordered a new pump, I believe it would be the same as the '81, due to an update to the later pump. I would love to know if anyone has used the kit for the W126 in the W116, with success.

[Edited by '79 Super Turtle on 02-18-2001 at 04:54 PM]

I show in my books and in the films that the 116-120 and all 126 ch use the same pump, so my final answer is yes! You are proablly better off buying the whole pump in fast lane for 78.34 and be done with it.

['79 Super Turtle]

Thanks for the info, Doc, but since mine is repaired I just posted this for others benefit. It is nice to know a rebuild kit is available. I wonder why it does not show up on any searches for my year though? My local dealer also said that they don't have a kit available. I do agree that the price is better for a new one, than the kit.

I read a post by George Murphy the Technical Director of "The Star", on another forum, that said he had nothing but bad luck with the rebuild kit and that he thought it was mislabeled.

That is why I took his advice and went the simple route.

I would like to know if anyone has ever used the kit on a W116. Please feel free to post any experiences.

Its because it was a updated pump so the kit dose not work on the early version only on the version that has been updated alreday I belive τΏτ

['79 Super Turtle]

That's what I thought, I think your parts book lists my pump as the same as the W126, because it is an updated part no. If I had the updated pump already, the kit would work. Thanks for all your input, those eyeglasses are wild.

Try the rear entry. Take out the two screws and pull out the commutator and the entire motor internals are exposed. Rotor, brushes,and all connections. Takes about 5 minutes.

[john]

I recently replaced the brushes in the recirculating pump on my ML270CDI, this company supplied them, they also 'make to measure' for unusual sized brushes. Just either send a sample of the worn out brush or give them the dimensions.

I believe they will ship abroad.

http://www.solenttools.co.uk/p0/bosch-carbon-brushes/314051.htm