Best Sealer for thermostat gasket & antifreeze

[Joseph P. Indusi]

I used to use the old Indian Head shellac type gasket sealer, but what is the best of the newer ones,  the black or blue or other?

Joe, BCA 33493

[old-tank]

Use lots of red or blue RTV so everyone can see where it squished out...that will seal it, but not it looks like a chevy.

If I have time I use a thin coat of black RTV and let it dry before installing; if in a hurry, then I brush on the brown stuff or use an anaerobic sealer

Edited August 10, 2017 by old-tank (see edit history)

[Bhigdog]

Call me old fashioned but good ole aviation Permatex pretty much does it all......................Bob

[Grimy]

Depends if you anticipate removing the part again during your ownership.  In such cases, use black RTV on the most difficult edge to clean, and the excellent Permatex #2 on the easier edge to clean--usually the part you can put on your bench. For example, I'm replacing an in-radiator t'stat which operates shutters, and the radiator surface is difficult to scrape, so it will get the black RTV.  If you have a cooling system pressurized above 7 psi, you may need to Permatex both sides.

 

Same holds true for oil pans and side valve pans--the block side gets the RTV.

[Frank DuVal]

Permatex High Tack

 

https://www.permatex.com/products/gasketing/gasket-sealants/permatex-high-tack-gasket-sealant/

 

The "strings" will drive you nuts, but it works well and parts come apart and clean up later. Put some on every surface, wait (contact type cement), assemble parts. if you use it sparingly, nothing sticks out like the horrible looking RTV gushed out of every seal.

 

There are lots of sealers out there. Most work. Some get sworn at, some get sworn by.   My west coast friends suggest Gascacinch. Others like "Right Stuff" RTV. At least it is black....Nothing makes "restored" cars look ugly like red/blue/orange sealers! 

Edited August 11, 2017 by Frank DuVal (see edit history)

[Aaron65]

I'll second Bob on the Permatex aviation sealer (#3).  It cleans up easily and seals well.  I've used it on all kinds of threads and gaskets, but I always use it on water pump and thermostat gaskets.

Edited August 11, 2017 by Aaron65 (see edit history)

[Guest]

I'll third Bob, but I have put many gaskets on dry and have not had any of them leak either.

[Daves1940Buick56S]

+1 to Bob. I am old school, at least by today's standards, Permatex #2 (or #3).

 

Cheers, Dave

[Joseph P. Indusi]

Now I see why I used to use the old style stuff on thermostat gaskets and elsewhere.   Thanks for all the advice.

Joe

[NTX5467]

The black high heat silicone sealer finger-smeared on ALL sides of the gasket, even the edges, allowed to cure prior to installation. Great sealing, easy to disassemble and clean.  Might even be re-used with just a bit more smeared and allowed to cure, saving the gasket and $$$, IF done right.

 

#2 Permatex on bolts and bolts that go into the water jackets.  Be careful of the bolt torque as the sealer can act as a lubricant for the threads.

 

NTX5467