Water pump stealth failure?

Brett Dikeman quattro at frank.mercea.net
Fri Sep 29 17:15:35 EDT 2006

On Sep 28, 2006, at 10:09 PM, Jim Jordan wrote:

> Does anyone know a way to check the water pump short of removing it  
> and
> inspecting it?

I wasn't aware they could "fail" in any manner that didn't involve  
seizure of the bearing and shredding the timing belt, since the  
impeller is VERY solidly attached to the pulley/shaft.

> I drove the car on the freeway today about 50 miles total, ambient  
> temp was
> 90+ F, and the temp gauge sat just under the top mark when driving at
> highway speeds.

"Top" mark?  If you mean the "fat" marking just to the left of the  
gauge icon, that's perfectly normal, especially in 90 degree weather;  
I think in the summer my 200q20v is always hovering around that mark.  
That marking on metric cars is 90 degrees C, or 194 degrees F.  Keep  
in mind coolant does NOT boil at 100C.

Normal operation is between the first two thin lines.

Read more here: http://www.sjmautotechnik.com/trouble_shooting/ 

>   I measured the coolant temp in the expansion tank just
> before shutting down at ~180 deg F.  The fan came on during driving  
> and shut
> down shortly after I shut the engine down.

If the car is truly overheating, you'll get the stage 3 fan (which  
never comes on otherwise), no A/C, little boost, and the battery will  
be dead in short order as the alternator usually can't keep up for an  
extended period of time.  On my 200q20v, the third stage kicked in  
around the first 'dot' on the gauge, and I've had the coolant cap pop  
at the second (fusible link failure, doh!)


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