size bolts? catalytic converter replacement

[kirstburstkiki]

Hello everyone,
I'm trying to remove my rusted bolts and/or nuts on my catalytic converter, but no luck. I tried all kinds of rust remover and the bolts are just becoming round! Most likely going to cut them off... and buy new ones. Does anyone know the size of the them? I cant tell if im removing the actual bolt or just the nuts?
Both the top of the cat (3 bolts and 1 off to the side) near the engine and the bottom of the cat (2 bolts) that connects to the muffler. Thanks in advance, sorry completely naive to everything. Just a newbie here
I know it would be easier to take to a muffler shop... but im a hands on type of person! i like to learn the hard way i guess
Oh just an fyi I am replacing this cat with a direct fit aftermarket and i dont have a torch to heat the bolts off...im thinking cutting them off or trying a bolt extractor? any other ideas??
99 Toyota 4runner sr5 3.4L

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[19963.4lsr5]

The two at the muffler and tail pipe I used stainless. Just matched up size at hardware store. Haven't had the others off yet.

 

[The Deec]

when I replaced everything downpipe back I used 9/16th Head Bolts which slide in perfectly and also slid right in at the triple bolt flange without hitting in the pre threaded side( just barely). Im not sure about yours since you have the other style of flange. It took me about an Hour to remove each of the three bolts at the triple flange... Lots of PB blaster and vise grips on the bolt to back it out given that my bolts split in half with any sign of torque. The bolts are dual threaded, counter clockwise for attaching to the upper manifold flange and then regular for your bolts on the lower flange. I took my time and removed the dual threaded bolts so i could just use new ones. Install is so easy, Removal seems to be the bane of the 4runner ha.

 

[Robb235]

I went through this same thing last year. It sucked. All the PB Blaster in the world didn't help me, neither did the torch. I rounded off all the nuts, and had to cut them off with a Drimmel. Then I took my drill and drilled out each stud, which took time and drill bits. I then went to Home Depot and got some bolts, nuts, washers, and lock washers to put it back together.

 

[animator]

Those nuts are split locking nuts, and can be quite difficult to remove. I got two out of the three on the flange, but had to cut the third one off. I replaced them with OEM nuts from the dealership. I don't remember the price, but it was cheap.

Same with the bolts and nuts after the front cat. Dealership had them for a few bucks, so it was an easy choice.


If you're careful with a dremel, you can cut them off without damaging the threads on the studs. I cut most of the way through on two sides, then used a chisel to knock the halves off. No damage to the threads that way.

 

[19963.4lsr5]

My toyota dealership doesn't stock anything needed. When you go there their parts room looks like the room at work you get printer paper and ink cartridges from.

They did have two blank keys for me.

 

[Nelsonmd]

Ugh, yeah those bolts are a PITA. I ended up having to actually cut one of the bolts out (couldn't get my drill way up there to drill them out). I used my dremel to cut a slot in the flange that ended at the bolt, then made a wedge out of a piece of strip steel I had lying around, and pounded the hell out of it to pop the bolt out (it was completely frozen thanks to the New England love of salt, salt and more salt. I'm pretty sure someone here in MA has a family member in the salt business). I then just replaced it with a bolt and nut from autozone, and now if I have to replace it again (God forbid...), I can easily pop out that bolt and out a new one in.

On the plus side, your's doesn't look nearly as rusted as mine did.

 

[Robb235]

Ugh, yeah those bolts are a PITA. I ended up having to actually cut one of the bolts out (couldn't get my drill way up there to drill them out). I used my dremel to cut a slot in the flange that ended at the bolt, then made a wedge out of a piece of strip steel I had lying around, and pounded the hell out of it to pop the bolt out (it was completely frozen thanks to the New England love of salt, salt and more salt. I'm pretty sure someone here in MA has a family member in the salt business). I then just replaced it with a bolt and nut from autozone, and now if I have to replace it again (God forbid...), I can easily pop out that bolt and out a new one in.



On the plus side, your's doesn't look nearly as rusted as mine did.

Wow, so you actually cut a slot in the exhaust flange and essentially pried it open enough to knock the stud out? Am I reading that right? Wow...

As far as the drill not fitting, I ran into the same problem. Home Depot sells some really long drill bits that I used to get at the stud, after I cut the nut and stud off flush with the exhaust flange. It was a real PITA.


At the top right of the picture, you can see one hole drilled out, and another where I used grade 8 bolt, washer, and lock washers to replace the stud.

 

[Nelsonmd]

Yeah, you got it right, you can see the pictures here: http://www.toyota-4runner.org/3rd-gen-t4rs/150176-cat-replacement-hell.html

I bought a couple of those long bits too, but they just weren't sharp and hard enough to really dig into the metal of the studs that are on there. I know that Toyota used some pretty hard studs in the exhaust, so I gave up and went a different route. I don't think there will be any issues with the slotted bolts, and they will be a cinch to replace later if it comes to that.

 

[jdpoissa]

Hey folks, I am going the muffler (south of cat, and north of tail pipe), I already know I will need to replace the nuts and bolts. Anybody know the hardware that I will need to do this job.

So far, I am going to buy:
1. The muffler
2. 2 gaskets (south of cat, north of tail).


Thanks for the input.

John