Run Dry Impellers

[Midnightsun]

Always someone to throw a wrench into the theory right?

Even if you were to double or triple the water flow from the pump it will not affect running temperature. The thermostat opens and closes to keep it at its set temperature and has nothing to do with flow. All excess non essential cooling water is simply bypassed.

Not sure why you are seeing different temps. Could be the new impellers are producing less flow, water is colder than a witch's tit and even with the thermostat fully open it cannot achieve rated temp is my best bet.

[Cooler]

The other difference is the type of T-stat. The old ones were the style with kind of an enclosed bottom. The new ones just have an open coil type so nothing like rust can plug up that bowl. Maybe they are just not opening as far, until I get the RPM's up under load for a while. We will see, testing continues. er

[km1125]

I wonder if there's not ENOUGH of a restriction in the path from the raw water pump to the exhaust and that's why you're seeing more flow out the exhaust and the higher engine temperatures. Not really anything directly to do with the difference in impellers, just an issue. On my Crusaders there was a "poppet" or something spring-loaded in the thermostat housing that would force flow though the engine unless the thermostat specifically blocked it off, then it would be forced through the 'poppet' valve and out the exhaust. That way there was always plenty of water to satisfy the thermostat's preference for controlling temperature.

[Cooler]

Update: Took a good cruise. The engines ran great! Temp would hit 180, then drop to 168-170. From a previous post, it sounds like this is almost ideal and I may get better fuel economy. The T-stats are obviously working, just not at the 160 temp they are manufactured for. er