I am constantly failing thermostats and on top of that they fail and stay closed and cause severe over heating.... What could it be? What causes thermostat failure?

My head gasket is fine, I don't have leaks, my fan is on a manual switch and I keep it on, I run distilled water and water wetter

I'm using a password jdm half size triple core radiator with 14 inch zirgo high performance fan (2700 cfm) pusher

Ps. When I run an open thermostat it only overheats on the hwy after about 30 min that's why i think I need a thermo but they keep failing within 2 miles of driving

Edit: it's an integra with a b18c1 darton mid sleeved 84mm with copper sprayed head gasket, samco hoses and im also running coolant lines from the front of the block to the turbo and back to the top of the radiator


Any suggestions and help will be greatly appreciated

 

Ahhh ha! Figured out my issue....

Come to find out, the place I had bought my hondata intake manifold gasket hadn't sold one in so long that when I bought mine, it was still the old design that did not have a thermo bypass hose. Come to find out I wasnt even running one, which would explain everything. I wasn't having bad luck with thermos not opening, they just didn't know when to open cuz of the lack of a bypass hose