No thermostat?

[Gerald]

I don't think the thermostat opens at 120 F. I believe most open at 190 F.

I never ran a engine without the thermostat. I have had to clean out small sticks and leaves, but not gunk'ed up.

After washing the thermostat with a hose to remove the small stick and leaves, I would boil the thermostat on in a pan on the stove. You would be surprised how much more stuff comes off the thermostat when it "opens up". I did not take a picture after boiling the thermostat.