Thermostat installation question

Well i am changing out the thermostat in my 91 xj. Guy at napa said i didn't have to put an rtv sealant on just the gasket. Don't know if this is right or not so that is why i am asking. Should i put rtv sealant and the gasket or just the gasket? Trying to make it so that it doesn't leak.

Thanks,
Ben

In my opinion, gasket sealers are highly overused. The gasket does the sealing and not the sealer. The only time I use any sealer is when the surface is questionable or if I am reusing the gasket due to temporary unavailability. If you do choose to use the RTV, use VERY little. Remember that whatever squishes out when you tighten it down, the same amount squishes in. I don't know about you, but I don't like RTV running through my cooling system.

So i should just use the gasket and that is it?

88 Wagonman said:

In my opinion, gasket sealers are highly overused. The gasket does the sealing and not the sealer. The only time I use any sealer is when the surface is questionable or if I am reusing the gasket due to temporary unavailability. If you do choose to use the RTV, use VERY little. Remember that whatever squishes out when you tighten it down, the same amount squishes in. I don't know about you, but I don't like RTV running through my cooling system.

Click to expand...

Or RTV can be used to hold a gasket in place and free up your hands.

Use a VERY thin layer - enough to hold the gasket in place - and that's all you should need. If your cleaning job and the surfaces proper are up to scracth (no gouges/nicks/scores/other problems,) the gasket will do the job.

Gasket sealers are, in the main, overused. I'll either use them when there are known issues for installation (valve cover gaskets on the I6,) known issues down the road (manifold gaskets on inline sixes - especially on side-draught heads!) or when using the stuff will free up my hands (gaskets mounted vertically - like the thermostat housing.)

Even then, if I can get away with it, I'll use a stud to hold the gasket up instead of RTV (axle covers, stud in top hole.) RTV can be a pain in the arse to clean...

I lay a very thin bead into the recessed outer ring. It's not necessary, but if I'm in there why not.