NewbVetteGuy

Question: Should I use some sort of sealant when installing a new thermostat & gooseneck?

If so, what kind and where?


Adam

The Punisher

I know some of the new goosenecks come with an o-ring which requires no sealant. If you are using stock with a gasket I would use a little blue RTV

NewbVetteGuy

Thanks. Where does the RTV go?



Adam

Buccaneer

Is this a stock GM type neck with the a slightly raised bump all around in the center of the neck flange? If so, you do not need any sealant at all using a Felpro paper gasket. Make sure its clean and dry and just bolt it down, torque to spec, it shouldn't leak. Also, it doesn't matter which side faces up, blue or striped. If it does matter, Flepro always puts it on the gasket which side faces up.

mark79,80

I would recommend putting some anti seize on the bolts. I had a 1979 which has an aluminum intake and the bolts seized to the aluminum. Next time I changed the thermostat one bolt snapped. The bolt holes are blind holes, so no danger of fluid weeping from the manifold.

NewbVetteGuy

lionelhutz

Good choice. I would have highly recommended a 2-piece aluminum housing of that type compared to using a cheap 1-piece cast chrome aftermarket housings.

c3_dk

I have a adjustable with o-ring, for that I don't use anything.
For the old style would I use RTV on both sides of gasket.

NewbVetteGuy

Dumb luck, really. I knew I needed adjustable and I knew I wanted polished aluminum and that's what's for sale today. I'll take dumb luck when I can get it.


Adam

Tonio

As Buccaneer recommended; don't use any sort of sealant with paper gaskets. Let the gasket do what it's designed to do; make a watertight seal with nothing else in the way.

gkull

This is what better engineered c-3 vettes use. It makes it so you can completely fill the radiator system?

https://www.summitracing.com/parts/mor-63420/overview/

Buccaneer

Also...Using no sealant on Felpro paper gaskets is also true for the water pump contrary to popular belief. The plain paper gasket will work just fine and not leak. Clean and dry, that's it.

Mooser

Also check the mating surface of the intake. If it's an old aluminum intake they are sometimes pitted and the O-ring may/will not seal properly and then you'll have to make a bunch of posts on how O-ring housings are crap and that you'll never buy another one.

Or, if it is pitted, simply put some right-stuff (or sealer of your choice) on and then a paper gasket and your o-ring gasket on top of that (with no sealer)

Some even remove the o-ring and use just the gasket, I'd leave it, easier to remove later if need be
M

keithl1967

I never had an o ring seal properly...even on brand new to brand new surfaces. just unlucky, I guess!!

I always use a felpro gasket, and always put a thin coat of RTV on each side of the gasket. perhaps a bit overkill, but never a leak!

7T1vette

No sealant on the T-stat. Sealant on the gasket(s), if needed. I much prefer Permatex Gasket Sealer to any kind of silicone sealant. The only time I will use a silicone based sealant is on oil pan or valley cover corners; and then Permatex Ultra Black RTV is the sealant of choice.

lionelhutz

Was it a housing similar to an Edelbrock 4818 or a o-ring type seal around the outside of the thermostat?

I had one like the 4818 and used it on and off a bunch. Got rid of my last small block that could use it so Dad now has it on his 78. Have not changed the o-ring yet and no leaks yet.

Buccaneer

I know there are plenty of people out there that think you need to seal the cooling system gaskets with sealant, but that is old school thinking for sure and I'm not trying to be condescending here.

If the surfaces are in good shape, flat, dry and clean, there is no reason you need to use sealant on water neck or water pump gaskets. Felpro, if used, was designed to be used without sealant even though they are paper.

Go here at the manufactures site and do your research on the subject, ask questions if needed. If you are leaking, check your bolts.
http://www.felpro.com/professional-forum.html

keithl1967

always the cheap chrome ones (maybe therin lies the problem), with the o ring around the outside of the stat.

Jebbysan

If the aluminum is in good shape on the intake.....then no sealant is needed if it is FLAT.

Take the water neck and put a piece of 80 grit on a flat plate or granite stone to check and make the surface flat. Do this to the intake also if it is off the engine of course.

And that is exactly what I did with my OEM GM neck......I also heli-coiled the intake and used ARP bolts......I'll never have a problem.

Jebby

dan1495