[GTS Dean]

This bastard bolt…
tried heating with a propane torch and turning with a vise grip.

Where did you apply the heat - the bolt itself, or around the bottom of the female threads in the block? You definitely want to get the aluminum to expand around the steel bolt, then do as Recluse suggests above. Spray the bottom of the welded nut with penetrant, then use a punch and hammer to hit straight down on the bolt shank several times. Then, start rocking the welded nut back and forth.

As tight as yours is, you may be headed to a TimeSert installation too.

 

[GTS Dean]

I think we need to recommend to all Gen 2 owners that T-stat gaskets get replaced every 10 year no matter what. The gaskets start to break down and coolant seeps out into the housing bolt threads. If your car has never had the intake off, you should look closely for signs of leakage and prepare for the worst.

That also means that intake gaskets are replaced at the same time. I was looking at my hex/torx bolts last night when installing my intake and found the 3 that had been on the t-stat housing before the engine got built. It was easy to spot them. Now I use them on the intake where they stay dry.

 

[GTS Dean]

Now, you need to look at the block threads and see if they are good. You might use a rifle bore brush to clean the threads, or a bottom tap. If they are corroded and have lost thread area, you should definitely look into TimeSert repairs. Probably should do all 3 if you have to do one.

 

[GTS Dean]

Much more accurate in this case.

 

[GTS Dean]

I do them dry.