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Old 10-15-2009, 05:35 PM   #1
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Removing stock Catalytic Converter

Anyone got any advice on this? I haven't started yet...but mine is literally falling apart. 206+ thousand miles, and it's still the stock cat. It is shaking, rattling, buzzing, loosing chunks, you name it, it's doing it...It's got to go. I'm thinking the magnaflow cat offered at quadratec (Magnaflow 23221 - MAGNAFLOW Performance Direct Fit Catalytic Converter for 93-95 Jeep® Wrangler YJ with 4.0L & 2.5L Engines - Quadratec) So, anyone got advice on whether that's a good one? What problems will I run into removing it? (94 2.5L 5 speed)

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Old 10-15-2009, 06:24 PM   #2
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It's been a while since I've had a stock exhaust but if my memory is correct the exhaust is welded so you would need to cut the old one out and weld in the new one. It might be best if you have a muffler shop do it unless you have access to a welder.

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Old 10-15-2009, 07:53 PM   #3
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I used a direct fit magnaflow from jegs for my XJ. I had to cut mine off. I used a sawzall and I cut it as close to the cat conv case as possible. then once the cat was off an out of the way, I slotted the the remnants of pipe all the way to the end of the cat pipe (I know that probably doesnt make sense, so if you need more inof just PM me and I will explain it further) once its slotted you can spread it open with a screwdriver and pry it off the other exhaust pipe. once you put the new cat converter on, it will slip right over top of the part thats slotted so you dont have to worry about exhaust leaks
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Old 10-15-2009, 09:23 PM   #4
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Mmmkay. I'll probably PM you in a few days. I have a question though. I know with too little backpressure you can actually do damage to your engine and it's seals..if I were to "forget" to put a Cat on until my next inspection, would that do anything negative? Cuz it might be awhile before I can get a Cat anyway...so I'm sorely tempted to just buy an exhaust pipe from advanced auto and stick it on there.
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Old 10-16-2009, 11:54 AM   #5
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Anybody have any idea what size the exhaust pipes are on either side of the converter, just to make my life easier? I'm putting in a straight pipe until my next inspection..I could measure it, but that requires waiting until I take the cat off.
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Old 10-16-2009, 12:08 PM   #6
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Quote:
Originally Posted by Pylonpounder View Post
Anybody have any idea what size the exhaust pipes are on either side of the converter, just to make my life easier? I'm putting in a straight pipe until my next inspection..I could measure it, but that requires waiting until I take the cat off.
{slides out soapbox and steps up}

Why don't you make life easier for future generations and just go get the darm thing replaced? {steps off and slides box back into the corner}

Paid a whopping $400 and a shop replaced the cat and welded in a Flowmaster 40. 1-1/2hrs and I was driving home no fuss no foul.
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Old 10-16-2009, 12:19 PM   #7
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i have no cat, no problems
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Old 10-16-2009, 12:51 PM   #8
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{slides out soapbox and steps up}

Why don't you make life easier for future generations and just go get the darm thing replaced? {steps off and slides box back into the corner}

Paid a whopping $400 and a shop replaced the cat and welded in a Flowmaster 40. 1-1/2hrs and I was driving home no fuss no foul.


He is not removing the cat he is replacing it with a Magnaflow one that looks like this...



I don't see the problem here.
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Old 10-16-2009, 08:54 PM   #9
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Because I AM getting the darn thing replaced...when I have the money, and time. Until such time...I'm thinking I'll go with a straight pipe.
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Old 10-17-2009, 04:39 AM   #10
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How long till your next inspection?
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Old 10-17-2009, 10:45 AM   #11
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Next september. Also, Anyone have any experience with gibson cat-back systems? Their description says "Mellow" sound, and I'm not really sure what their definition of mellow is. Because there's a possibility that I might also do a cat-back when I do this...and gibson seems the best for the money so far, but I don't want to get it and have it sound like stock :P
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Old 10-17-2009, 10:53 AM   #12
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Oh, I thought you were only going to run cat-less for a month or 2. I would go without a cat that long, but that's just me. I don't know anything about the Gibson exhausts but I do like the Flowmaster 50 series delta flow. It's nice and quiet until you mash the skinny pedal and it still has the traditional Flowmaster sound. I'm running one.
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Old 10-17-2009, 11:15 AM   #13
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Mm. In all likely hood I'd get the cat before the inspection by a long shot..but who knows. I do TRY to be eco-friendly, most of the time. And hmm, I haven't seen that one...got any idea of a website where I can find it? I've seen pacesetter, dynomax, magnaflow, and Gibson..no flowmasters for jeep that I've seen
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Old 10-17-2009, 11:29 AM   #14
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Having looked at JPmagazines exhaust shootout, and taking into consideration that mine is the 4 cyl and not the 6 as theirs is..I'm stuck between gibson and dynomax. Gibson sounds very truck-ish on theirs...but it's also a video camera, and the 6 cyl...dynomax sounds nice for them, but will probably be a little nicer sounding on mine...so I'm still stuck on gibson or not.
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Old 10-17-2009, 12:22 PM   #15
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Quote:
Originally Posted by coyote_94yj View Post
Oh, I thought you were only going to run cat-less for a month or 2. I would go without a cat that long, but that's just me. I don't know anything about the Gibson exhausts but I do like the Flowmaster 50 series delta flow. It's nice and quiet until you mash the skinny pedal and it still has the traditional Flowmaster sound. I'm running one.
What's the problem with running no cat for a prolonged time. I'm wondering bc I haven't had mine on in few months.
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Old 10-17-2009, 02:13 PM   #16
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So, a number of problems; my skidplate is pretty much stuck on. with a 2 1/2 foot breaker bar, a 16 inch pipe added on, PBlaster, and a 300 ft/lb impact gun, I got ONE bolt to spin...and spin is all it did. Also, my cat is clamped on..which, unless it's also welded on, is actually a good thing. Anyone got ideas on how to get those clamps off? I'm thinking hack saw, to be honest. It'l be a pain, but it'l work.
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Old 10-17-2009, 04:10 PM   #17
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Quote:
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What's the problem with running no cat for a prolonged time. I'm wondering bc I haven't had mine on in few months.
Emissions. Carbon Monoxide, Hydrocarbons, and Nitrogen Oxides.

Quote:
Originally Posted by Pylonpounder View Post
So, a number of problems; my skidplate is pretty much stuck on. with a 2 1/2 foot breaker bar, a 16 inch pipe added on, PBlaster, and a 300 ft/lb impact gun, I got ONE bolt to spin...and spin is all it did. Also, my cat is clamped on..which, unless it's also welded on, is actually a good thing. Anyone got ideas on how to get those clamps off? I'm thinking hack saw, to be honest. It'l be a pain, but it'l work.
A hack saw or angle grinder with a cutting wheel will get the exhaust clamps off.

I used a 5ft antenna mast as a cheater bar to break mine loose.
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Old 10-17-2009, 04:54 PM   #18
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I just put a eastern catalytic catalytic converter part #EAST70421 mfr#70421 from Car Part Wholesale for $48.87 and a Thrush Weld Muffler Part #289-17651 for $32.99 at Jegs they sound great and don`t cost a arm & a leg.
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Old 10-17-2009, 10:02 PM   #19
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That'd be good, But I'm not just looking for the sound..I'm looking for the reduced backpressure, and the sound to boot.

And okay, thank you very much for the advice.
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Old 10-17-2009, 10:18 PM   #20
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So, a number of problems; my skidplate is pretty much stuck on. with a 2 1/2 foot breaker bar, a 16 inch pipe added on, PBlaster, and a 300 ft/lb impact gun, I got ONE bolt to spin...and spin is all it did. Also, my cat is clamped on..which, unless it's also welded on, is actually a good thing. Anyone got ideas on how to get those clamps off? I'm thinking hack saw, to be honest. It'l be a pain, but it'l work.
The shop that did mine never pulled anything....So no issue with plates that are stuck or won't come off easily.
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Old 10-17-2009, 10:20 PM   #21
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That's good to hear. I may just bring it a shop.. Never done one, but I know several people who have..and both say they did one and never did another, so I guess I'll learn from them.
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Old 11-03-2009, 05:49 PM   #22
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I am new here and I am going to piggyback on the Pylonpounder thread. whiteyj has answered my question already in regards to leaving the plate in place when removing the cat. I am thinking of cutting the pipe as it crosses to the passenger side. I would then remove the complete exhaust. I plan on coming under the frame just behind the spring mount and have a side exit exhaust like the CJ'S used. 95 Wrangler, 4cyl.
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Old 11-03-2009, 07:38 PM   #23
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Im not sure about your state but in pa if your vehicle is 95 or older the exhaust system is just visualy checked so what i did was cut the old cat off clean out the inside honey comb and weld it back on or if you want to you can cut off the old cat slip a one size smaller pipe through the center of the old cat and tack weld it(or bolt) to the new straight pipe and then clamp the new straight pipewith the old cat atteched back on to the exhaust system
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Old 11-03-2009, 09:44 PM   #24
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I ended up cutting the header pipe just before the cat, getting a slight extender/adapter to make it the size needed, put on a Magnaflow high-flow cat, and also a Dynomax super turbo Catback. Not that that answers your question, but hey.
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Old 11-03-2009, 10:00 PM   #25
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Did you remove the skid plate or were you able to do the work with it still in place?
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Old 11-04-2009, 02:21 PM   #26
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I left the skid plate there, which is why I ended up needing an extender/adapter. The header pipe swells up just before the cat, and I had to cut that portion off, so I needed an extender that fit the header pipe before it's swell, and swelled up to the size required to fit the converter. (The one I got went over the header pipe, and into the converter) Measured the circumference, divided by Pi, and wallah, had exterior diameter.
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Old 11-08-2009, 08:44 PM   #27
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Hi guys as far as catalytic convertors go .... removing it from the vehicle WILL NOT hurt the engine but in a majority of the country it is illegal

Check your local laws online and verify that it is OK .....if you don't drive your jeep on the road you are usually exempt.

I just picked up a 95 YJ with a plugged cat for 300 bucks ....they thought the motor was bad since it wouldn't rev past 2200 RPM ....the honeycomb fell apart and acted as a check valve at the outlet of the converter

Visual inspection tells me the motor was running overly rich OR it had been too long since the last tune up was done.

For alot of you with older jeeps or ones with a ton of miles ....either buy a backpressure check gauge or have a shop perform this service.

If you have a bad convertor or its beginning to fail you will loose power rather fast and gas mileage will drop significantly.

As for the skidplate removal I highly reccomend using a propane or MAPP gas torce to heat the bolts then break them free .....yes they are a PITA but heat will help coax them out.

The best option to replace the cat would be to remove the entire exhaust system then weld the new one in place then re-hang the exhaust ...this will provide ample working room plus its WAY easier to weld around all of the fittings.

best of luck

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Old 11-09-2009, 04:21 PM   #28
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Replaced old cat and muffler on Saturday. Bought a Walker cat and Dynomax muffler. Not that hard once I got started. Lowered the skid plate (No frozen bold story!), cut in front of the cat and behind the muffler. Cut loose all the rusted mounting points and replaced with clamp style hangers. JB Weld and a clamp at all connecting points. Hardest part was sizing and finding the transitions from the exhaust to the cat and muffler to the old exhaust. Took a few trips to 3 parts stores. Ended up slotting the end of the exhaust transition to reduce its diameter. Took me all day but I was in no special hurry.

The cat was totally shot. Crap falling out of both ends. I test drove to make sure nothing rattled and it felt like it had more power. The sound is great too, noticable without p---ing off the neighbors. Finished off the weekend by modifying a brush bar from a CFC Nissan Pathfinder for the front end. But that's for another thread.

Thanks to everyone who posted. I had all the answers before I started.
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Old 11-09-2009, 09:00 PM   #29
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wow... this thread would have been easier if I found it before I had to replace my CAT whilst having no idea what I was doing
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Old 11-09-2009, 10:06 PM   #30
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Anyone got any advice on this? I haven't started yet...but mine is literally falling apart. 206+ thousand miles, and it's still the stock cat. It is shaking, rattling, buzzing, loosing chunks, you name it, it's doing it...It's got to go. I'm thinking the magnaflow cat offered at quadratec Magnaflow Catalytic Converter for 93-95 Jeep® Wrangler YJ with 4.0L & 2.5L Engines - Quadratec So, anyone got advice on whether that's a good one? What problems will I run into removing it? (94 2.5L 5 speed)
I an using the same cat and love it

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