I have replaced the Gasket twice. The Stat Housing is newer with no Corrosion. It is flat. The Intake Manifold Outlet is flat. I have always used a Gasket and Gasket Maker (Permatex etc) together. Never had a problem. Doing some reading it is not recommended to use a Gasket and Gasket Maker together. Just use a Gasket Adhesive. I cut my Gaskets from a Sheet about 1/8 inch thick. I have one thin Paper One left from a Gasket Set. I would have thought the thicker Material would be better to use? Any Tips anyone wants to offer that You find works?

  

Are you sure it is the gasket leaking?  Those pressed-in tubes for the bypass hose have a history of rusting away right at the casting.

John - "The Hoosier Hurricane"

The guys who build a lot of engines will know better than me, but I’ve been using this on paper and cork since Dad taught me to use it way more than 60 years ago.

https://www.permatex.com/products/gasketing/gasket-sealants/permatex-form-a-gasket-no-2-sealant/

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Its leaking between housing and Manifold. The Housing is newer. Bypass tube is good.

  

Sometimes the bolts just need to be tightened after a few heat cycles.


Lawrenceville, GA

Mark: also put some sealer on the bolt threads, might help..


Paul

I had the same problem with the paper gaskets. I changed mine 3 times and it would weep coolant every time. I even put sealant on both surfaces with no luck. I finally got a Fel-Pro gasket and it never happened again.

Durham Missouri

I had a water pump that a gasket wouldn't seal. I used Permatex Water Pump and Thermostat gasket maker and it stopped it. You put a bead around the sealing surface, thighten until it begins to squeeze out, wait 30 minutes, and torque

https://www.permatex.com/products/gasketing/gasket-makers/permatex-water-pump-thermostat-rtv-silicone-gasket/

I have used a thin film of ‘black’ RTV on both sides of the thermostat gaskets that just don’t stop weeping under normal circumstances.

Lorena, Texas (South of Waco)

My housing was just leaking last month. Last time it was apart 13 years ago both pieces showed corrosion. Before disassembling it ordered a reproduction housing with by pass tube installed, and a replacement tube to install into my old housing as an option.. I decided  to install new reproduction thermostat housing. Its been thru several heat-ups and no problems. I have never use form a gasket or any other silicon type sealer. I always use a LIGHT coat of gasket shellac/sealer on all surfaces and take a paper towel to remove any excess. Let dry for 10 minutes and assemble. Always works for me.