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Old 20th January 2012, 22:19   #10
T-Cut
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Rover75 and Mreg Corsa.

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Quote:
Originally Posted by Mike Noc View Post
Probably due to the difference in the pipe diameters of the two circuits.
The second valve will bleed off excess pressure when the coolant is only flowing through the smaller heater matrix pipes, and allow full pump flow when coolant is flowing through the larger radiator pipes.
How much force is required to compress the small spring say half way? Is this likely to be similar to the pressure drop across the water pump? The spring looks relatively hefty, but I've got little feel for the pumping pressure. I've not seen the spring in a PRT for example, but I do know the 1.8 PRT starts opening when the engine's only at 2,000rpm. I guess the pump will be running at 2-3 times that rate looking at the drive diameters. Running the engine up to 3 -3.5K rpm or even 6K rpm seems untennable for a water pump. (???)

TC

Last edited by T-Cut; 20th January 2012 at 22:22..
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