Decided to throw three 180* t-stats into hot water. Lower right is a NAPA FE t-stat that was in the engine when it was built and on dyno day. Upper right is a NAPA replacement I installed about 10 days ago when I tested the lower right and decided it was opening late (~190*). Gold t-stat is the new Cobra Velly hi-flow. It is the one that has been in the engine since last weekend when I added the new fan and final repaired/painted/pressure tested expansion tank.
The gold one and the upper one started opening around 185F, and the lower right at 190 as stated before. All were wide open as you see here by 200*. The hi-flow will pass a LOT more water than either of the NAPA units. The lower right unit is much more restricted than the upper right, though both are NAPA models for FE. Its interesting that on cool down, the lower right one went closed first at 190 (which makes me think its mis-labeled) and the upper right closed at about 175-180*. But the hi-flow stayed open all the way down to 150*. Again, I know this is not my entire problem, but it could be contributing. If the hi-flow is opening and staying open, then the coolant in the radiator doesn't have time to cool it just races on through. Not sure its the best one for the job.
P.S. Yes, they all 3 have 1/8" holes in them.
