Re: 93 90hp force thermostat spacer question
Oh, yeah----forgot about the steel ring. It has been so long since I opened one of those thermostats that I have trouble remembering exactly how they went together. I THINK the thermostat actually fits inside the spacer and the spacer is open at the bottom to allow full water flow when the thermostat is open--the cover is filled with the top of the thermostat and the spring, restricting water flow.
Is it necessary? Well from the standpoint that the factory does not spend unnecessary money to put in unneeded parts, yes it is necessary. Can you get by without it? Most likely yes. Can you make one? Yes, easily. Just bend up some 1/16 inch aluminum. make the band wide enough so the gasket compresses against it. That is, the surface of the band should be even with the surface of the head.
OR---You can spend 20 bucks (exaggeration) for a new one at your Mercury dealer.
Again, I believe its primary function is to hold the seat tight against the head and the spring is there to hold the thermostat against the seat-- al little bit of redundancy since the spring will hold both against the head