its really hard to tell cause a thermostate has been known not to perform as it should....Running hot sometimes is hard to define such as a car cutting back...too much fuel or not getting enough fuel.
with this said by eliminating the mechaincal function of a thermostate you will isolate the problem......i know i have went on saying water moving to quickly thru a block will cause heat problems...but also water moving to slow or not at all will cause the same problems..
when you gut the thermostate you are taking the guess work out of the thermostate situation....
i'm i making sense///LOL//or i'm i confusing you ?... :lol:
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give it a try and see what happens..
let us know.
Brian