I've taken 2 sets of cats out on 2 different cars and all I did was put penetrating oil on let it soak,do it again the 2nd day and take it apart on the 3rd day all came right out.:tup:

Demon bolts kicked my butt once again

Yup. I'm bringing this back from the dead. I'm on my last bolt and it's completely seized. It's demon bolt #2 on passenger side. The drivers side wasn't actually bad. I'm 50% out and its totally seized.

Things needed to do this project:
alcohol
zanex
bolt extractors
no family or children within a 5 mile radius to hear you cuss

Why Nissan? Why? 16 years of building cars and I've never seen such silliness

Spray lube on her and let her sit. Then come back and heat her up maybe? If worst to worst, you might want to try and drop the transmission (sucks but not too bad) to get easier access to her. If your going to drop the transmission, make sure she is as high up as possible.

Here is a pic to show how much room you can have.
http://i226.photobucket.com/albums/d...ps358bf50c.jpg

YzGYz

Try applying Kroil or PB Blaster to the bolt. Kroil has worked for me on the demon bolts and other bastard bolts on the Z and other cars.

You have to make sure it is applied to an area where it can easily seep into the gap between the bolt threads and the flange threads (think about how gravity acts on a fluid). I only feel like I have to say that because I have seen friends just haphazardly squirt it near the bolt and then complain when it didn't free up.

good luck!

1. Spray it with BP Blaster. Let it soak. Then see if you can run it back in a little. If you can run it in. Put some anti-seize on the threads. I've had luck at times doing this.
2. The other thing is taking a torch and heating up the flange cherry red.
3. If you got room. Hack saw the bolt between the flanges.

Stripped demon bolt, need idea
 

So, knowing that exhaust bolts are a pain, prior to even starting I soaked everything in PB and let it sit over night. Then sprayed it again in the morning. That evening got the drivers side knocked out in about 45 minutes. I thought "sweet, the passenger side will be a breeze in the morning" - what a dumb thing to think. I got the regular two bolts out immediately. Demon bolt turned two rotations with all my might and seized. So I the. Went from the front. I removed the intake box and used a 3 foot extension, slid it down and started pounding on it with my 1/2" impact - no avail. Eventually this all led to a rounded head. YES I was using 6 points. The bolt extractors did nothing for me. So I took a sawzall, and cut the cat out, by slicing up near the neck, just to get the piece of crap out of the way. I wish I'd done this originally.
I removed the other stud from the header flange and then used my 3' pry bar to bend the exhaust pipe flange back until the demon bolt was exposed.
Out came the grinder. Sliced through the bolt. *plop* done.
I quit. I'll put the res test pipe on this morning.

6 years later and I'm in the exact same situation as you, Gauge. My passenger side bolt came off easily, the driver's side bolt got rounded... Thought I was doomed as most shops refuse to touch this kind of stuff, but I stumbled upon this thread. Going to pick up some bolt extractors and give it another go today, wish me luck. Currently driving around with only one pipe installed haha