N14 motor mounts

Do you have extensions connected to those air wrenches? That really takes the applied torque away from them. Maybe try long pull handles.
If you have to use the blue wrench would it possibly be easier to cut the bolts on the out side of the frame rail? Try to stay away from all the air lines and such?

 

Wow that sounds like a real tight spot.

I don't know what you call it but I do think there's some type of flame retardant material that if you wrap all that in it won't allow anything to actually catch on fire. I don't know about the heat getting through but it will stop anything from catching on fire.

The best advice I can give you and I'm sure you already know this is to really be careful where you point your flame.

If you can't completely get the nut red hot all the way around at least get one side super cherry red hot and get the other side whatever much of it you can catch. The heat will still transfer to expand the metal so hopefully your big gun could zip it off. I have had some really bad stuff to get apart but if I really got the nut super cherry hot I got it apart.

I don't like trying to cut nuts out of situations like that because the tight fit makes it so difficult that you may actually damage the motor mount itself.

If you can get in there well enough to really get that nut hot and you still can't get it out maybe you can spin the bolt from the top?

 

Nut seized or the bolt is seized in the sleeve?

If there's air lines and such in the way, honestly I think I'd support the engine/transmission and take the entire mount bracket assembly off. Then you can torch the mount bolts out without fear of melting harnesses and air lines.

 

Can you get a grinder on the nut. I have removed part of a nut to relieve the clamping force and that allowed me to turn the nut off with a socket. I don't know how much room you have.
Good luck

 

A carbide bur might work too. Easier to get in to tight spaces than a grinding disc. My biggest worry would be the bolt being seized in the steel sleeve of the mount vs the nut being seized.

 

As said too, about being careful with the flame, I just went through this with some 1- 1/8 bolts holding my trailer shocks down. I was heating the whole bolt, bracket and everything. This caused the bolt to swell up. Once the bolt was swollen, it would not fit through the yoke price of the bracket. Only options I saw next were to heat the yoke piece and hope it expands or cut through the part of the shock that doesn’t have gas, get the bolt more exposed, and keep cutting. About 5 cuts and a day later I got that one. The nuts were seized unlike ive experienced before. My 1/2 Milwaukee gun with 1100 ft lbs reverse wouldn’t get it. I made all sorts of 4-6 ft breaker bars. Used all sorts of sprays.

but the heating all of that I did my self a disservice. You probably already know to just heat the seized part only though!

 

My experience with seized shock bolts. Its quicker just to cut/torch the eyelet in the shock and bolt to remove. New bolts are cheap.