Anyone replaced the cat themselves? [Archive]

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cali-ti

10-21-2005, 04:28 AM

Has anyone replaced the catalytic converter themselves? I'm wondering how ugly it is to disconnect the header from the pipe to the cat here (parts 2, 7 and 8):

http://www.realoem.com/bmw/showparts.do?model=CG73&mospid=47506&btnr=11_1086&hg=11&fg=50

mischief

10-21-2005, 04:50 AM

well handtools well strip the bolts so use a air gun
its not hard

cali-ti

10-21-2005, 05:00 AM

my bolts/screws that attach there are completely rusted. i doubt there are threads there at all ... the ends of the bolts/screws are basically rusty blobs. i don't have a compressor ... yet. i figure i'll need to drop the cat/exhaust when i go to do the flywheel/clutch so i'm trying to figure out what else i'll need to get the job done. i'm doubting an air wrench will get them off either. i can't post pics until i get back home next thursday or friday.

Viper3812

10-21-2005, 07:44 AM

I had the pipe cut off for mine and put a clamp on.

cali-ti

10-21-2005, 11:12 AM

I had the pipe cut off for mine and put a clamp on.
yikers! i was hoping i'd be able to cut the bolts/screws off and then pound them out or something, but space is so limited in there ...

i really hadn't planned on getting a new exaust manifold/headers :censored:

aceyx

10-21-2005, 07:49 PM

mischief

10-21-2005, 09:10 PM

cali-ti

10-21-2005, 10:29 PM

Try using bolt-outs. I have a pair of roller-style I'd be willing to lend you but I think the grip-type would work better.

Depending on how rusted they are, you could just bang on 'em with a hammer until stuff falls apart. BTDT.
i'll have to search out some "bolt-outs" on ebay or another source. you have any recommended brands/specific products in mind? i'd rather just get my own than try to work a lending deal :)

cali-ti

10-21-2005, 10:35 PM

if its that bad then you should spray the bolts with some PB blaster to get some of the rust off clean the rust with a wire brush then heat the nut you can buy a small torch at any hardware store
http://www.ge.uiuc.edu/ge342/equippic/torch.jpg
this works very good
i have a torch just like that that i've never used, lol. any good purchasing source for PB Blaster? i've read about this stuff when i googled "bolt-out" ... they seem to go well together :)

stormos

10-21-2005, 11:37 PM

i used penetrating oil on my callipers, 4 days of trying with wd40, a day with the oil stuff and off came what needed to come off ;)

aceyx

10-22-2005, 12:03 AM

Know what WD40 stands for and you'll know what it's not good for. PB Blaster is also my personal pick, but some people swear by Kroil and others.

Here (http://www.amazon.com/exec/obidos/tg/detail/-/B0000CCXVZ/103-0643070-6207824?v=glance) is a set of bolt removers. The Irwins are usually available at any Lowe's/HD. Sears also carries their house brand, but I'm not a fan of Craftsman stuff.

I'm thinking it might actually be easier to snap the heads off the bolts, and just use new ones since you probably don't want to use the old rusted ones anyway. Just crank the heck out of 'em and they'll probably go.

cali-ti

10-22-2005, 12:37 AM

Know what WD40 stands for and you'll know what it's not good for. PB Blaster is also my personal pick, but some people swear by Kroil and others.
true! WaterDisplacement ... doesn't help too much when this are already rusted straight to hell.
Here (http://www.amazon.com/exec/obidos/tg/detail/-/B0000CCXVZ/103-0643070-6207824?v=glance) is a set of bolt removers. The Irwins are usually available at any Lowe's/HD. Sears also carries their house brand, but I'm not a fan of Craftsman stuff.

I'm thinking it might actually be easier to snap the heads off the bolts, and just use new ones since you probably don't want to use the old rusted ones anyway. Just crank the heck out of 'em and they'll probably go.
lol ... yeah, i definitely don't plan to reuse the bolts/screws! you'll really find it amusing once i get back home and post a pic of what they currently look like :) i'm wondering if my current air wrench would even fit in the limited space. if so, i wonder if it would be worth getting a small air compressor (i wanted to avoid it until we had a house so i could get a stand-up air compressor for the garage). looks like i'll have even more tools here before too long, lol.

i'll keep my eye out for a deal on those irwins or something equivalent. the flywheel/clutch combo is probably at least a year away. i'm not sure i want to do a pre-emptive strike on those bolts to get 'em prepped ... although it would make access to the shifter easier for installing the short shift kit i'm planning to get. then i'll use lubro-moly copper anti-seize on the bolts and nuts when i re-assemble to (hopefully) keep it from going down the same rusty path. are there any hardened steel bolts/nuts or anything that would resist the effects of high temps, road salt, etc to not rust?

thanks everybody for the suggestions!

cali-ti

11-03-2005, 04:17 AM

here are some pics of my future removal hell:

http://www.318ti.org/gallery/showphoto.php?photo=878&cat=530
http://www.318ti.org/gallery/showphoto.php?photo=879&cat=530

aceyx

11-03-2005, 06:38 AM

cali-ti

11-03-2005, 03:50 PM

Holy monkey, that's horrible.

PB-Blaster it overnight, and for about an hour in the morning. Wipe it down, then give it a go.

Hammers and blowtorches are nice to have. Just make sure it's dry of penetrating spray (not sure if that stuff is flammable or not) and stay away from the fuel lines (duh).

Eric, you should just snap those suckers off. Either overtighten (you'll probably want to use a new gasket anyway) or just crank it with a breaker bar.

i'm sure i'll use some combination of your suggestions, perhaps ALL of them! LOL

luckily, the fuel lines are on the other side of the car. hopefully it won't come to torches, but we'll see when i actually go to do it. i have new BOLTS (not those damn screws) nuts and a gasket coming. i also have a set of the bolt removers you pointed me to on the way (the irwin ones). gonna be fun, i just know it!

cali-ti

12-02-2005, 02:53 AM

un-FREAKIN-believable news! i let 'em soak in PB Blaster for a couple days, then gave 'em another dose maybe an hour before starting work on it (i removed the front sway bar and cross bar before even thinking about doing the cat pipe).

i first figured out it was a 14mm nut. i made the decision, "these things are coming off, come hell or high water." i grabbed my el-cheapo (i think that's the actual brand :tongue:) 1/2" electric impact wrench and the 14mm impact socket. with a little prayer, i hit it ... and it came off! i couldn't believe it (especially after my earlier task of drilling out and tapping the weld nut so i could screw in a helicoil had worked too!) ... the bottom one i had to use a 14mm box end wrench ... which i hammered with a dead blow hammer to get it started. same with the one on the other side ... things were coming off and i just couldn't believe it! the top one is tricky ... i was trying to figure out what i could use to actually get it off. box end wrench couldn't get on there. i tried a socket with a pivoting section in the middle but couldn't get the torque on it i needed to break it. out of sheer whim, i tried a socket and a long extension ... sure freakin' enough, i could get STRAIGHT at it! UNBELIEVABLE! i grabbed the 14mm impact socket and a 4" extension and hit it with the impact wrench ... came right off! the cat section is now off.

just for everyone's info, the screws are welded onto the headers (at least for the 96s) ... unless i were to cut the head and tip off and then drill it out, i wouldn't be able to replace them. so ... those four $15/ea bolts i got will not be used to reassemble (luckily the nuts are the same for each).

i'll have to take pics tomorrow because the batteries in my camera decided to die a little earlier on (when i was working on taking pics of the steps to using the helicoil kit).

to repeat ... I CAN'T FREAKIN' BELIEVE THEY CAME OFF! :biggrin: