I recently changed the thermostat on a 1994, 1.3 toyota corolla.
The thermostat has a rubber ring that sits around the thermostat and the two halves of the housing join up meeting at the rubber ring. In the thermostat box was no gasket of the size I needed and the Haynes manual makes no mention of using any gasket other than the rubber ring.
On one half on the inside was a small flaw in the casting, just a small lump which sits under the rubber ring which I still dont think is really significant. But there is a very slow leak, below the thermostat housing.
Should I have applied some sealent of some kind to the two flat metal faces? If so what kind of thing should I get? Thanks for any advice.