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Re: Water pumpin'

In a message dated 96-10-09 18:33:12 EDT, you write:

<< > did my T-belt this summer and put in a GRAF pump that appeared to
 > have a slightly larger impeller blade than what I took out, and I think
 > car does cool a bit better.
 A bit "more" perhaps, but is it "better"?
 All engines are designed to run hot.  For any given engine, there's a
 value.  You'll find the value for each engine given on the thermostat - 
 typically on Audi engines it's 87 Celcius.  Any cooler, and you run the rick
 increased wear.  The pistons, for example, are oval when cold and only
 round at operating temperature.  The trick in providing cooling capacity is
 handle high ambients and high engine workloads - the water pump in all Audis
 more than capable of handling worst case loads, but the radiators and fans 
 thereto may have a bit more work to do. 
 -- >>
Phil is right on here....  Specifically, you want engine temps to read at
100C, that is the optimum design temp perameter for the 5 cyl audis...   This
has some leaway in it, cuz, most engines operate hotter than the thermo open,
measured into the 250F range on the 5ktq during the summer, before temp
mods....   You run the motor too cool, your gas mileage sucks, the car never
idles right, and you tend to burn more oil than normal......   Phil is right
that the water pump isn't the prollum, it is the radiator and the oil coolers
and the design of the thermostat (head temps high, thermo at block on the low
side, so by the time thermo opens, head at REALLY hi temp).....  Me, I would
put on only an aftermarket oil cooler, at least double the size of stock, and
let it do the "extra" work for you....  The radiator is currently a very
expensive upgrade (tho working on a more efficient, all medal one @
reasonable price).....  If you are running higher than stock boost pressures
and modified turbos, the problem becums more acute......  9 times out of 10,
the water pump on R&R is fine, it is the rubber O-ring that is leaking
btw....  I have a lot of cores around that are still good, tho replacements
run below 50.00USD, so prolly well to do it while there....