Thermostat problem

[Mazza]

Decided to get on and replace the thermostat this morning as the car has been running cold (according to the temp gauge).
Got it all stripped down and cleaned but I have found there is a bit of pitting where is bolts on. It’s not too bad but a bit concerned that it may leak.
Is it ok to use a sealant , if so what would be the best one to get?

 

[t-tony]

Silicon (instant gasket) is what you need.

Tony.

 

[Mazza]

Can any explain why the dimensions are different? And is this going to be a problem?
The depth of the housing is about 39mm, but the new thermostat is only 33mm.

 

[Mazza]

Found a good silicon sealant, sorted thermostat query, flushed the system, put in new coolant and as the song goes.....’Back on the road again’

I must admit when it was in this state was a bit nervous but that’s how you learn