I am pulling out my old factory cat to replace it. I got all the bolts loose and cut off the band clamp at the front but it won't come off. I'm talking about at the front where the pipe from the cat is flared and fits over the pipe coming from the manifolds. It doesn't look like its welded on, but I've been wrestling with it for like an hour and it won't budge. It should be pretty obvious if it was welded, right? Any tricks for getting it off?

I don't want to just cut it off becuase the flare is so close to the bend in the pipe goin to the manifolds that it won't leave any room to stick a new flared end on when I replace the cat.

I have also loosened the small band clamp around the AIR tube.

I'm working under the ar on jack stands with limited clearance, so cutting is going to be a huge pain if I go that route anyway.

Any ideas or suggestions? Thanks.

 

Its probably rusted together. You'll want to try WD-40 or Liquid Wrench or those type of fluids. Or some heat from a torch if you have access to one.

 

I used a cut-off wheel to cut the flared end of the cat longways. (Think of the path the air takes coming from the engine towards the cat... cut in that direction)

Just be careful that you aren't cutting through the y-pipe.

Once you get four inches or so cut, the flare opens up nicely.

It took about one minute to cut the metal. The cat slipped right off.

 

Try PB blaster it works the best on rusty exhaust parts.

 

If youre lying under the car, using your hands, you wont have nearly enough leverage to "wrestle" it off.

I had to fight with a freind's 1993 F150 who's exhaust we were replacing.

My tips:

If you havent disconected the exhaust from the cat back yet, use it for "leverage" and move it side to side or up and down as much as possible to free it up.

What worked best for me, is using your legs though. Just kinda sit down next to the car, put your feet up against the side of the cat, and just "leg press" the thing back and forth till it frees up.

 

liquid wrench and wd40 both suck use PB blaster. Try some heat and a hammer. or you can cut a slit in it and then just bang it off

 

Its settled. I'm going to buy a dremel and cut a slit in the flared pipe end. Wrestling with the cat with the car on Jack stands is too much of a PITA. Thanks for the help.

 

I recently had to perform this operation also. Spray PB Blaster up and around the cat. Take a screwdriver and break up the rust all the way around the pipe. Then take something larger like a chisel and get it in there as far as possible. I really think you should start from the other end though. Since it's sort of socketed in there it'll be a little bit easier to get out and will really help from getting the other end off. Of course, I did it opposite and it made things... FUN. We'll say that. Anyway, good luck on the project.
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OK or that.

 

Well the dremel diddn't work. It took like 30 minutes to cut two lengthwise slits in the flared end, and then I wedged a screw driver in and tried to pry it apart...still no luck. This is not worth the trouble. I will just take it to see a friend with a reciprocating saw later this week. That might not leave me enough y-pipe before the bend to flare a test pipe and put it on, so I'll just get one welded in. I have spent my whole 4-day weekend trying to get the cat off and trying to remove the stripped bolts holding my smog pump on qith no luck on either and now I'm frustrated. This is not worth saving the $30 to have somebody weld a patch in, versus fabricating a test pipe myself.

 

That sounds pretty rough.

If you have two lengthwise cuts already, just use the recip saw and cut through the cat side. That way, you don't cut up the y-pipe.

I can't possibly imagine the flare not coming off if you cut it twice lengthwise and back cut it.

The dremel tool took me about 1 minute to cut the pipe lengthwise and it slid right off. Can you take a picture?

Make sure your cut is long enough. I think mine was at least 4 inches. Basically, you want to let the metal let go of the y-pipe. That U-Clamp really puts a dent in both pieces, so that is what you are fighting against, more so than the rust.

 

i was gonna say that the dremel wouldn't be powerful enough, I used a porter cable with a cut off wheel

 

I'm pretty much limited to a dremel. I don't want to spend a bunch of money on new power tools for this.

 

I just broke out the BFH and whacked that mother****er and wrestled it outta there, heat and pb blaster helps

 

What kind of cut off wheel are you using? Do you have the number? I am using the metal cut-off wheel that came with it. i think its a 456. It almost seemed like the wheel wasn't up to the task. Like I said it took a good 10 minutes to make the 4 inch cut. even in just one spot it would take a minute or two just to cut thru the pipe. maybe I need a better wheel. I spent like 10 minutes cutting on a bolt head, too and only got like halfway thru it.

I would take the pic, but there are lots of reasons why this isn't worth pursuing. I am working in my apartment parking lot and every night I have to take the car down off the stands for safety, and at least onceevey day this weekend it would storm suddne;yand I'd have to grab all my tools and run back up to my second cloor apt. Jst not worth it on this job.

Thanks for the help though. I'd like to know what wheel you used for future ref.

 

Well take a hammer and screwdriver and start on the side. Once you get a little spot open it's all easy from there. Here is what I suggest...

From the beginning...

1. Put PB Blaster on all the bolts, joints, and anywhere else that your going to need to move something apart from that has rust.
2. Loosen the bolts in the back as much as you can. When you can't go any further re-apply the PB Blaster on the joint and bolts. Wait...
3. Loosen the bolts in the back further. When you get stuck again re-apply the PB blaster again. Now try to pry out the joint in the front.

I remember I started removing my cat at 9:30pm and decided to quit until the next day at around 1:00am. It's all because I was patient in letting the PB Blaster on there. Mine was REALLY rusted on there. I mean... really bad. Before i went to bed I sprayed the joints and bolts again and took duct tape and placed it around it to stop it from running off.

I'm a very determined guy. once I start on something... I'm not going to give up. So... Don't give up. It'll budge. After I was finished my hands were really cut up and body was sore (I had sunburn on my back, OUCH), but it was all worth it. I have no regrets.

 

Heavy Duty Cut Off Wheel #420.

I don't have a lot of experience with my Dremel. My buddy showed me how to just let the tool do the work. If you are applying a whole bunch of pressure, you will just break the wheel.