Water pump longevity ????

[78F350]

Originally Posted by JFP in PA

Can't agree to eithier point.

We have run 160F stats on fully insrumented cars and consistenly found both lower coolant and more importantly oil temperatures when operating at steady state (cruise speeds). Coolant temps typically drop from around 205-210 to the mid to high 170F range. Oil temps drop 20-25F. Used oil analysis on cars befor and after adding the low temp stat showed the oil was in better condition after equivlant usage.

We have had multiple cars in the shop that had metal impeller pump failures that resulted in significant damage to the engine cases behind the pump. Several of these cars showed coolant circulation issues after being fitted because the new pump lost efficency due to the increased gap behind the impeller. Trimming impeller blades is a method to slow pump circulation rates, which is an old racers trick to improve high engine RPM cooling as usually the pump is moving coolant too much coolant under those conditions. But like everything else, there is a "too much" limit in doing this, when the reduced flow leads to over heating, particularly at lower engine RPM levels.

There are reasons the factory used compostie impeller pumps on these engines, and why they equip all of their high performance engines (turbos, etc.) with 160F stats from the factory.

That and what this other guy said that I was about to quote:
(From 2012)

Originally Posted by JFP in PA

In actual fact, it works the other way around: As noted above, the combination of engine vacuum in the sump and 170-180F coolant temps has demonstrated (by multiple used oil analyses) that there is no fuel or water contamination increase when running the lower temp stat; and the lower oil temps afforded by the lower coolant temps lengthened the oils ability to stay in grade, not shortened it.

Originally Posted by JFP in PA

Actually, there is substantial empirical (ranging from improved UoA’s, to even a pre and post install Dyno pull or two) to anecdotal (“improved fuel mileage”, “faster warm up in cold weather”) data available on this subject (ad nauseum), but that would require actually doing a search to understand why changing the thermostat is a positive, and in which models Porsche already uses them from the factory.

So, yes, these things actually work……………………..