Turbo after-run coolent pumps

Bernie Benz b.benz at charter.net
Thu Sep 13 20:09:52 EDT 2007

Mine just failed, started to leak at 215K. Believing that 16 year old  
cars don’t deserve new parts, I decided to disassemble and repair the  
old one, as follows.

The two piece impeller housing is apparently ultrasonically welded  
together, a failure in thIs flimsy weld line being the leak source.  
Because the weld line is flimsy it is relatively easy to break the  
weld all around the circumference and separate the two halfs intact.  
This reveals that the impeller axis is independent from the motor  
shaft and the two are magnetically coupled, a great improvement over  
the older 5KT pump which used a mechanical rotary shaft seal with the  
impeller mounted on the motor shaft, a major leak source.

After cleaning up the interface surfaces, the two halves can be  
reassembled by solvent welding using ABS pipe cement, there being  
lots of surface for a wide area, strong weld.

The next generation Bosch design, as used on my ’02 A6 2.7T, has  
eliminated the flakey weld and is screwed together and sealed with an  
O-ring. If one must replace with new, use this pump. Bosch #0 392 020  
039, Audi #078 965 561.


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