emailed the guys at evans antifreeze. here is there reply. had several from them...
Robert:
Without the thermostat housing in my hands I'm at a disadvantage.
First thought would be to thread the bypass hose nipple for a plugg of some sort. It does not have to seal 100% and a tapered pipe plug might put tooo much pressure on the casting, be careful!
Second would be a plug that fits in the hose ( did not see a good photo of the hose configuration) again it does not have to seal 100% but must stay put. I have had car guys that crafted a gutted thermostat with a spring that held the bypass foot closed all the time, depends how clever you are.
WHatever you decide to do, make it reversible. Sometimes completely plugging it off does not solve the problem and causes the lower hose to suck shut. This means that a smaller orifice (restriction) in the plug would help keep the hose inflated with some bypassing coolant. This is definitely trial and error testing.
Good Luck
Dave Wright
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Dave Wright
Technical Sales Manager
Evans Cooling Systems Inc.
T: 888-990-2665 x207