Does anyone know the value of the metal insulator placed between the 2 heatriser gaskets? I had an exhaust leak and mine is burned through. Wondering if I can install new gasket and leave the insulator out?
If you're talking about the flapper valve between the intake and exhaust, you do need it.
When the engine is cold, it directs warm exhaust onto the bottom of the intake manifold. When the engine is warm it diverts the hot exhaust away from the intake. If the valve isn't there or is stuck open, the heat will crack the intake manifold.
I replaced mine with a new one from Toyota. I don't think it was very expensive.
Actually not the flapper valve, but there is a thin metal insulator sandwiched between the gaskets that sits between the flapper valve and intake manifold. I had the crack welded and reinstalled last night. So I have all new gaskets in the exhaust system and still have a mystery leak. I'm getting very nervous that I might have a blown head gasket!