Mazda Repair: 1994 Mazda Protege Cooling, thread chaser, gasket material

Question
Have a 94 Protege with 150K and temperature hand rises to hot due to leak at the thermostat housing.  What I found was that one of the two bolts holding the thermostat housing to the engine has stripped and the bolt (innermost bolt) is no longer tight allow antifreeze to leak from this location.  What are my options??  I though about helicoil inserts and retapping the block, but it's very tight in this location.  Is there another option that I can pursue?  

Answer
The easiest thing to do would be to find a bolt that is slightly longer than the one that is currently installed. If the bolt is too long, use a washer or two to make it the right length.

You can also use a "thread chaser" to straighten the remaining threads. A correctly sized tap will also work as a thread chaser. I think the bolt hole has a 10 x 1.25 thread. Make sure that your thread chaser is the correct thread by threading a nut onto one of your other bolts and then onto the chaser. You can also make sure the threads are correct by meshing the bolt threads with the thread chaser's threads. If they mesh perfectly, then you're in good shape.

Take the assembly apart, remove all residual gasket material and silicone. Make sure all mating surfaces are dry and clean. If you are going to use a thread chaser, use it now. If you have access to compressed air, use it to clear any metal left behind from the stripped threads. Test your new bolt by assembling the thermostat housing with the gasket and thermostat installed. Determine if washers are needed, and if so, how many.

Apply silicone to both mating surfaces. Heck, apply silicone to both sides of the gasket while you're at it. Note that is important to use a safe amount of silicone. If too much silicone oozes out of the sealing area, it can cause an obstruction. It can also break free and obstruct other areas of the cooling system like the radiator. Usually I recommend that people use silicone sparingly, but in this case, we are using it to make up for another problem, so we're going to use more than usual.

Install a new thermostat and assemble the thermostat assembly with the gasket. Tighten the bolt, but if you feel the threads of the stripped bolt hole start to give, stop tightening immediately. Let the silicone dry as long as you can. Over night would be good. Add antifreeze and distilled water. Start the car and check for leaks. Make sure the car is completely warmed up before deciding that the leak is fixed.

Shopping list:
10x1.25 Thread chaser or tap
Thermostat
Gasket
Antifreeze
Distilled water
Blue silicone