So other than actually running the pump the results don't appear as dramatic as expected.

Based on your non-scientific results :-)Disregarding the higher outside air temperature for a moment.

Oil temperature drops at a rate 17% faster with the lower temperature thermoswitch.


Coolant temperature rises less with the lower thermoswitch (expected, but only 5º less), but then drops at the same rate as the normal switch then levels off after 10 minutes at the 199ºF point where the pump isn't running anyway.


It seems like the biggest benefit is in the IAT decreases. IAT rises at a rate 56% slower with the lower temp thermoswitch, but again are only seperated by about 10ºF and at some point both would level off.


So it would seem the normal function of the afterrun coolant pump would be to rapidly reduce extremely high coolant temperatures and their resultant pressures on the cooling system after extremely hot shutdown. Even with the normal thermoswitch coolant temperature is just boiling 212ºF. The normal thermoswitch would kick on the pump at 234ºF or about 7-10lbs of pressure. By reducing the thermoswitch temperature it really just allows the pump to run more often, but maybe it simply isn't useful to run the pump at that low a temperature.

"If the coolant temperature is too high, thermoswitch for coolant circulation run-on F95 activates the additional coolant function. The high temperatures which occur at the exhaust gas turbocharger produce vapour bubbles which prevent coolant being drawn in by pump V51. When pump V51 starts up, the coolant flows through the exhaust gas turbocharger and the cylinder heads. The direction of flow in the turbocharger cooling circuit is reversed by this. Due to this reversal of the direction of coolant flow, coolant is drawn in via the cylinder heads (large cross-sections), which means that any vapour bubbles which develop are expelled
from the exhaust gas turbocharger lines. The electrical coolant circulation pump again draws in coolant along the rear coolant pipe, thereby recirculating the coolant."

Future:
2009 A4 2.0Tq Tip
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Past:
2001 B5 S4 6spd