I replaced my thermostat recently since I had the housing off. The old thermostat had what appeared to be a rubber ring around the edge of the unit. The new one does not have one. I did get the gasket that seals the housing. My question is does a rubber ring seal go around the actual thermostat?

 

Depends on the outlet housing and intake if the O-ring is required or if it is just a gasket. You should see a recessed shelf in the intake if it uses an o ring, if it is more or less flat with just a slight shelf for the thermostat then use a gasket. From the factory yours should have been using the gasket with a flat water outlet.

 

Good to know. I'll check it later. Thank you!

 

Here's the picture. Based on your description, and my lack of knowledge, I don't know if I should or not use a rubber seal around the thermostat. There is a tiny bit of sideways movement when the thermostat is in. Seems all the ones I find for the car are ones that do not have the seal.

 

on a SBC? I've never seen a oring. The housing you have is probably flat, in which case, use a gasket

 

Yes, the housing is flat. I will just use the thermostat as is. The person who had it before me had a thermostat with the rubber ring in it so I wanted to be sure. Thanks you two!