okay for those of you keeping your evo nearly stock, this ones for you. This is just an update on the efficiency report by my 2003 evo with 32k miles. Just inspected thermostat and related components. It seems as if there is leakage around the whole thermostat housing area. OE gasket has completely failed and saturated in coolant due to insuficient sealant on the housing. Thermostat gasket seems to be intact. Driving style is daily and spirited driving. Coolant was 50/50 crap I should have been using mitsubishi genuine. anyways, this was just an informative post so I hope this is of some use.

 

its not a gasket its an o-ring that should be used. and there should not be any sealer used..

 

so your saying I'm I liar? your also saying the service manual is false? your also stating that the mitsu engineers are wrong and your right? no my friend....no. It states to use sealant on the thermostat housing area on top of the thermostat and also on top of the "gasket" for the housing area closer to the cylinder head my friend.

 

okay my question is......sinse it says to use a sealant in the manual in volume 2, does the thermostat housing area need only a liquid sealant (permatex liquid gasket) or both the sealant and the gasket? I know that the top of the housing that connects to the hose needs the thermostat o ring, but the bottom that connects to the cylinder head is what I'm confused with. The book says only sealant and then torque it up. like a liquid gasket sealer that comes from pep boys. Someone please clarify.

 

nevermind its all good. Sealed up with the permatex water outlet stuff(greY). The thermostat housing side that is closer to the cylinder head that is. Also the top side of the housing is sealed with the permatex stuff as well. No gaskets needed says mitsu. Only the O-ring on the thermostat itself.