Thermostat seal

[85Rangerr]

I removed the thermostat from my truck and noticed there was no gasket. It looked like someone used silicone before instead of a gasket. I ordered a new gasket for the thermostat but it does not fit. At this point I just want to use silicone or RTV, is this okay to do?

 

[Shran]

Yep fine to use just RTV. Just make sure you let it sit overnight so that it fully cures.

 

[DILLARD000]

Is this the large ORing that sits on top of the ThermoStat? If so don't recommend RTV.
Local part store should have an ORng that fits.
If its the gasket below the ThermoStatHousing then PermaTex HiTemp RTV works good;
do let it cure at least a couple hours before filling wih Coolant.
Can also do old shadetree trick, cut your own Gasket from cardstock.