Frozen trans case overfill plug on Boxer

Well I finally have my new clutch in and working on my 78 512Boxer, but I need to refill the trans since I drained the transfercase for clutch removal.

The trans overfill plug is frozen and the soft bolt has deteriorated to rounded corners, I tried vice grips with a small pipe for leverage and its still rounding the plug head more.

So the next step is heat, I would heat the surrounding area of the bolt on the case so it will expand correct? Any concerns with heating the trans case or does anyone have better idea?


Also the plug is in a tight spot so an impact wrench will not work after the bellhousing had been reinstalled.

Thanks in advance

 

Thanks for the reply Tom and Michael


Finally got the SOB out, I used a propane torch to heat the bolt several times then sprayed water on it to rapidly cool it to shock the plug, I did this several times, then finally heated the area around the bolt for a few minutes spraying around the outside of the plug area to keep heat from spreading beyond the plug area, and took a good quality pair of vice grips with a small pipe cheater and finally broke free.

Interesting over a quart at least of trans fluid gushed out, my assumption this bolt probably has rarely been off if at all, the so called shop that this car was serviced by just drained the trans fliud and filled to book specs without properly checking the level.

 

I could see that happening, or the aluminum catching fire or warping etc., I hated heating it myself and was very concerned doing it but I was out of options and drilling it out would be a nightmare that would take a full day.
The area was hot but not red hot, it would take a while for a propane torch to get metal glowing vs a oxy/acet torch would be glowing quickly.