So I'm trying to remove the passenger side muffler bracket, but the bottom bolt is so stubborn I want to give up. I have tried soaking with WD40, tried tighten a bit to break the torque, tried a few different 13mm wrenches and it won't budge. The bolt head is still in good shape. The way the bolt sits, you can't access with socket Advice greatly appreciated

 

WD-40 isn't a penetrant so that stuff will not help your cause. For these kinds of applications, its largely a placebo.

I'd recommend using a real, professional-grade penetrant such as Kroil, Zep's penetrating oil, Wurth Rost Off, etc. Give that bolt a soaking with any of these products, let it sit for several hours, and it should come right out.

You might need a little heat in the form of a propane or Mapp gas torch, but you can remove it without destroying the fastener.

 

Yeah, those are not easy to break loose! Like Steve mentioned, a good penetrating oil. Use a punch on the bolt head in the CCW direction trying to shock it loose -- just a few taps might help!

Also, if you can move or wiggle the bracket while trying to loosen it might do the trick.

 

Get a good tool that bites into the bolt like Snap-on flank drive plus wrench.

I've learned my lesson with cheap tools, even with Sears Craftsman. Their 10mm allen key is like 9.5mm. It stripped the bolt and caused me a big headache.

 

Kroil has yet to fail me ( any penetrant in Steve's list will do) ...... also, smack the head of the bolt squarely with a hammer, better yet with a brass drift held on the head if space permits - the shock serves to break loose the corrosive film that binds the threads.

 

Torch

 

From the appearance of the outside finish of that bolt-head, I'd bet the threads of it aren't even corroded.

Use a good quality box-end wrench, keep the head on square with one hand and give the other end a good blow with your other hand. Not being crunched up under your vehicle helps by giving you better movement. You are turning it counter clockwise?

 

The only way I got that bolt out was to dremel a slot into it and use an air chisel. It was scary, but the bolt came out.

 

Have you tried a box end wrench and hitting it with a rubber mallet?

 

Thanks for all the responses. The bolt is so tough that Im not even going to try any open ended wrenches. I was able to find a low profile box wrench. Thicker ones wont even fit in there because there's some doohicky looking "cup" of some sort about 6mm behind the bolt head. Im a little nervous about putting a torch down there....near oil and gas. Where can I get some Kroil?

 

I think it was the passenger side one on my car that gave me fits. Follow the suggestions above.

I think these are the guys in charge of putting those brackets on....

 

Sorry about that; its been two years since I had it off and a low profile box end is necessary.

If that is the original bolt, you'll only be able to loosen it but not remove it, not that you have to to get the muffler bracket off.

 

The muffler is off. The top bracket bolt came out easy. It's only attached at bottom bolt now. I tried grabbing the bracket and wiggled it up and down. The bracket moved, but the SOB won't! Like you said, the bolt head and threads itself look great. No corrosion that I can see peeking thru the open end of the lower arm. So frustrating.... I will try to get some Kroil. If that fails, I was thinking about shearing the head off

 

If you do that and I did to replace the bolt which was loose already but buggered up by a previous wrench, you'll have to remove that aluminum cap to get clearance to get the new bolt in.

 

Ah ha.....look what I got a hold of! Called my dad to search his "cave". I remembered seeing him use Kroil when I was a kid. Never thought he still has two cans sitting around. Just gave it a good coating