Question on R53 Water Pump Replacement

Nick, Your technical support is outstanding. Thank you.
In this Water Pump Replacement Article, one important step was left out. My personal experience has probably been the same as many others. It is pure luck that there was not a water leak after replacing the flange "O" ring described in your photos 37, 38, and 39. In my case, after having performed this procedure without a problem at least 4 times, my luck ran out. The result was a major water leak between the water pump flange and the water pump outlet tube. My first reaction was that I left out the "O" ring. After I tore the assembly down, I found the "O" ring was in place. Confused, I did a little google searching and found this Technical Bulletin:
Complaint: Coolant leak from water pump mounting flange
Vehicles concerned: R53 with W11

Cause:The connection between the water pump housing and the mounting flange on the crankcase is leaking. The rubber O-ring has been crushed on one side by incorrect centering of water pump to mounting flange.

Measure:
1. In case of customer complaint replace the two O-rings, part number 11 51 7 509 186.
2. Apply “Syntheso Glep 1” to the O rings, part number 83 23 9 407 778.
3. Refer to repair manual group 11 section 11 51 00 for proper water pump O ring replacement.
4. The following alignment procedure should be done in sequence:
a. align water pump to supercharger and tighten. refer to tech data for torque specifications.
b. align water pump to mounting flange and tighten flange. refer to tech data for torque specifications.
c. align supercharger to mounts and tighten. refer to tech data for torque specifications.
5. In case of coolant leak caused by water pump/flange misalignment, it is not necessary to replace water pump.

Nick, My luck ran out in my last maintenance operation. I spoke with a friend and he has been as lucky as me, which I expect has been others pure luck. The problem was that the two bolts which secure the flange were tightened down with the flange slightly out of alignment. There is about a 1/8 in of alignment tolerance. I thought it was centered, but, it was off.
My solution is to
1. Leave the two flange bolts loose.
2. Position the SC on the flange,
3. Position SC on alignment pin,
4. Draw SC up tight against the engine.
5. Move the flange with a long screw driver to help center it on the water pump tube.
6. Tighten the two flange bolts with a 8mm and long extension, as seen in attached photo.
7. Torque the SC bolts.
8. Pray



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This post was auto-generated based upon a question asked on our tech article page here:

[Nick at Pelican Parts]

Awesome info and thanks for taking the time to share it. I will have these notes added to the article.

- Nick