thermostat on a 350

Weld a jam nut on top of the bolt with a MIG welder. Often times the heat will break it loose. Heat generated this way is very intense & much more localized than using a torch & therefore much less damaging to nearby components.

I have worked as a Millwright for 31 years and this method has worked every time I have used it.

-- Best Regards Gordie

If you havent broken the head off yet...PING it! Take a steal punch and a hammer and hive it a couple solid, but not harsh, hits. Not guarenteed to work but its a good place to start.

thanx to everyone that offered a suggestion.

Actually it got cold enough to frost last night and when I went out this morning I had no problems whatsoever turning it loose.

Got it changed.

I had same problem,

I wound up drilling the slug out. Fortunately I got the drill perfectly centered on the slug and picked the correct drill size. After drilling, the threads of the slug just fell out of the inner threads and I didn't have to re-tap.

db