Ideas for Removing a Frozen Nut (or, How I Fubared a Simple Repair)
 

I have owned my 2004 Mazda 3 for 2 weeks and I've already managed to fubar something.

The passenger side engine mount on these are notorious for only lasting around 60k miles. They are gel/liquid filled mounts, and at some point the rubber inevitably tears, allowing the gel to leak out. My car has 114k miles, and was well overdue to have the engine mount replaced.

It is supposed to be straightforward. Access is easy. 2 nuts, 2 bolts, pop the new mount on, 2 nuts, 2 bolts.

Well, one of the nuts won't come off. It's a 17mm nut that threads onto a stud that threads into the engine block. The engine mount slide overs the stud, the nut tightens down.

Because of the length of the stud, it was difficult to get even a deep wall socket all the way over the nut. That was my first mistake. The nut started rounding off. I purchased a deeper socket, but the damage was already done, and it rounded the nut off further.

Many applications of Kroil, I gave it another shot. No movement.

Then I bought a set of Irwin Nut Removers (the kind that bite down as you back them off). I could not get it to bite sufficiently, even hammering it into place, so every time I started turning it, it just shaved off more of the nut.

More Kroil.

Then I thought that since the stud was topped with an external-Torx head, I would buy an external-Torx socket and just remove the stud and nut together. The head of the stud sheared off.

More Kroil.

Then I took a dremel to the nut, thinking that I could cut enough grooves in the side of the nut to allow the Irwin Nut Remover to bite into it. Despite many deep grooves, the Nut Remover still just shaves off metal instead of turning the nut.

More Kroil.

Then I took the dremel to the (now-flat) top of the stud, cutting a deep groove. I attempted to turn the stud with a large Craftsman flat-head screwdriver. The blade of the screwdriver is now twisted a good 20-30 degrees from its original position, and the stud didn't move.




What's left? Are there any options other than drilling through the stud? I was really hoping to avoid doing that.

I'd weld on a new nut to the end of the stud and remove it that way. Hasn't failed for me yet. The heat from the welding also helps loosen it.

--Ferdi

+1, This is what I was going to recommend as well. It sounds pretty messed up at this point, and short of drilling out the entire center of the stud and attempting to easy out it I don't think you have many options. I've had luck with drilling/easy outing, just make sure you drill deep enough that you drill through the entire stud, which will help relieve tension, and use the biggest/fattest high quality easy out you can find.

If you don't have access to a welder and there are enough threads left on the stud slide a wrench over the stud, thread a pair of nuts on, and tighten them together. Then unthread the stud using the nut closest to the engine.

Buy a can of mapp gas and keep a water spray bottle close by.

I was desperate and needed one of the turbo to manifold nuts off (the partially shrouded one on a 2860RS) so after rounding it a little then grinding my wrench to get more motion it still wouldn't budge. I had remembered the power of the air hammer. I had used it once to crack accidentally into a honda 90 kids ATV cylinder and marvelled at its metal eating power. I put in the pointy bit and aimed it at the turbo nut. So long as I was able to stop it from slipping off it would slowly turn the nut. As long as there is access I'm using this as a 2nd resort.
Give it a try.

Good ideas all, but no welder and no air hammer. My dad does have one of those small Campbell Hausfeld compressors.

I think I'm going to try cutting through the nut completely to release the tension. Then I can figure out how to remove the stud -- maybe flatten 2 sides of it with the dremel so that I can grab it with a pair of vice grips or something.

MAPP gas and torch should be at any big box home center. You need heat to break it free. Propane may work, but MAPP isn't that much more, and gets hotter.

There's a reason oxy-acet torches are called flame wrenches.

Huh, didn't know about those. I have a propane torch but will check those out.

Propane are the blue bottles, I believe MAPP is the yellow bottles.

Somehow you managed to turn a 10 minute job into a fiasco, I understand that this happens from time to time. I would cut the nut off completely and remove the stud after the mount is off. The mount is over and inch thick to you will have plenty to grab onto once the mount is off the stud.

Finally busted it today. Cut through as much of the nut as I could with the dremel, heated it up with the propane torch, and smacked the hell out of it with a cold chisel and a hammer. The stud finally came loose. The nut is still frozen on there. I don't know what kind of metallurgical process fused a non-rusted stud and nut together so tightly.

https://www.miataturbo.net/attachmen...ine=1397954918

https://www.miataturbo.net/attachmen...ine=1397954918

The other 3 mounting points all came out easily.

https://www.miataturbo.net/attachmen...ine=1397954918

The old engine mount was completely separated.

https://www.miataturbo.net/attachmen...ine=1397954918

https://www.miataturbo.net/attachmen...ine=1397954918

how many miles on that? that's what my motor mounts looked like on my altima at about 130K

Reading comprehension fail!

From the OP, second paragraph:

The passenger side engine mount on these are notorious for only lasting around 60k miles. They are gel/liquid filled mounts, and at some point the rubber inevitably tears, allowing the gel to leak out. My car has 114k miles, and was well overdue to have the engine mount replaced.