Thermostat housing gaskets

[object Object] Anyone ever have trouble getting the gaskets at the thermostat housing to seal up ? Pressure testing the system, both these gaskets leak.  I got some from Zed parts in uk, they leak. I made some from Fel-pro gasket material I have, they leak. I'm not a fan of using sealant unless specified, but idk, maybe. I've got some supposed nos ones coming. Both housing covers (lower thermostat and upper hose fitting) are flat and crack free. System was tight and leak free before dis-assembling the engine. Thanks

If you use gasket paper to seal the thermostat, you should coat it with a little silicone gasket sealant, as the paper alone does not guarantee a watertight seal.

  Many years ago, there was a paste called Hermetic specifically for installing gaskets in contact with water, pumps, thermostats, etc., but I don't think it is manufactured anymore.


 I remember that when you removed the part, you had to scrape off the remains of the gasket that were strongly adhered with a utility knife or a scraper.

  Translated with DeepL.com (free version)