Thermostat Housing Sealing

[Joel Talka]

What's the best way to seal a small block thermostat?? It's been decades and I can never get them to remain leak free!! My '66 just let loose after it had been run and shut down. I've tried sealers, two gaskets, etc. Looking for some recommendations! Thanks, Joel

 

[Gripper]

Aviation Gaskets - Silicone Gaskets - Real Gaskets Tennessee

 

[YY1]

There's a metal gasket with a silicone O ring made in.

I've used that and it works.

Hard to find the Mopar version, but they make it.

I've had terrible luck with chrome water necks, and also dissimilar metals- if you've got an aluminum intake, use an AL neck, same for steel.

 

[493 Mike]

I have purchased two of these and they seal perfectly.
Mike
TerrysAutoLab

 

[YY1]

This is the chevy one but they do make a Mopar version.

Mr Gasket brand-

https://www.ebay.com/itm/262069772229?_skw=mr+gasket+mopar+thermostat&epid=113000098&itmmeta=01KMN5PW7T0N0QVNVZ3QWJ3KV7&hash=item3d04935fc5:g:H20AAeSwl81poaVX&itmprp=enc:AQALAAABAGfYFPkwiKCW4ZNSs2u11xDBwJZxtBuTHvG/SZ7/wAN2FdV1kl63kxEcgDPKFM4hBLKTx0mOWer3jVbXakr6+64yG2efIBEb/3fqKLWgNe9CUPTHQPU35wRdyAzupTxecfRePO6+GL+vqtP69+8GJuK8xLKYWVgCiT5lRRV2st+4coNOqO3rRnC66NAUaya6vmj6w7WT500N92Z6HNVqruqZYDSX6wJUb6TSa85ILIYAObB3a/Pszsr68fHRaoBWe3IX/boLIqer7y9e8aQfOdiwtDKq3srp24LNzJTiTCSS4u00ACYLp4pZI7q2RiBJHfi3yJ3cEnET+XLyezINqrM=|tkp:Bk9SR5LE26WlZw

 

[hunt2elk]

Thermostat Housing Gasket - Chrysler, Dodge, Plymouth - Older V8 Engines - Silicone Gaskets - Real Gaskets Tennessee
I have had excellent results with these Real Gaskets. They are even reusable.

 

[WileE]

Do not use any of the garbage chinesium chrome pieces, they're guaranteed to leak.

 

[RemCharger]

If the neck is original, sand or file it down flat. They get bowed over the years.

 

[T Brashears]

A straight edge is a good investment. I check everything that has the possibility of not being flat,check your file too,some are bowed. Plastic carb spacers can be really crooked.

 

[Bob Lynch]

RTV Black, never had a problem.

 

[RR Fan Dan]

I have purchased two of these and they seal perfectly.
Mike
TerrysAutoLab

That’s pretty neat except one thing,

 

[493 Mike]

Hopefully that condition will not last forever.
Mike

 

[Charlie Brown]

That’s pretty neat except one thing,

View attachment 2014096

I use these on all my Mopar engines. They are bullet proof and NEVER leak. It's unfortunate about the tarrif issue though.

 

[Dennis H]

Mancini Billet. It not the sealer, it’s the housing itself.

 

[boboh1]

I use this stuff on different cars over the years and never had a leak.

 

[69L48Z27]

Make sure your bolt holes are cleaned out. The bolts are nearly the same length as the depth of the hole. If you can not get it to seal no matter what, usually means the bolts are bottoming out on all the gack in the hole giving a false sense of tight. No clamping of the housing.

 

[icetech]

I use aviation gasket sealer on both sides of the gasket.. have never had one leak.

 

[watermelon]

i would say the rtv/waterpump gasket stuff above … clean each surface before applying and rub down with some alcohol or acetone and let it dry for 10 minutes… apply maker to the engine and the housing separately and let it dry for 2 to 3 minutes … the get on finger tight … come back the next day and twerk it down … yes it must be twerked down


watermelon

 

[Joel Talka]

What's the best way to seal a small block thermostat?? It's been decades and I can never get them to remain leak free!! My '66 just let loose after it had been run and shut down. I've tried sealers, two gaskets, etc. Looking for some recommendations! Thanks, Joel

Wow, I am amazed at the possible solutions!! I should have asked this question decades ago.. My thanks to you all for jumping in!!