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Discussion Starter #1 (Edited)
I'm interested in a 98 12v and the owner says he's getting about 14mpg city. The truck has the original cat on it. New Air and Fuel Filters It's a 4x4 LB QC.

Could the cat be plugged up causing low(er) mileage?

He hasn't said anything else is wrong with it. Just low mileage. Anything else I should check when test driving it?

Thanks in advance
 

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check everything, put it on a hoist, drive it
 

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In my experience most cats start plugging at about 80k causing a drop in fuel economy and power.
Get rid of it as long as you live in a place where smog checks don't look for it.
 

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Get rid of that muffler as well, and get a good air filter on there thats not to restrictive like a BHAF or something.
 

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^^^Agreed the cat has to go, and if i were you i would get rid of the muffler, i took my cat and muffler off, and it sounds great, and is no longer restricted...
 

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Not sure if it's still available but you used to be able to buy a "test pipe" from the dealer to swap for the cat.
Made the elimination easy.
Part number 52019170AB
 

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Do you have a ball park cost of that "test pipe". I don't need the cat up here and I've got 166k on mine. Sounds like it's well over due unless the previous owner gutted it.
 

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My source says $53.93 for the test pipe.
It's been so long since I've removed a cat, most of them were gone 10 years ago, that I don't remember but think the cat is a different diameter on each end.
If so you can buy a reducer and short length of pipe from an autoparts or muffler shop for less money.
Or you can remove the cat and gut it out by several methods.
Just be careful, the dust is toxic.
 

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Thanks for the info.

The reason I asked is because I seem to remember the Cat having flanges that are bolted in place. I can't veryify that right now because I'm in Thailand. But if it is then it would be easier to get something made to replace than to hacksaw everything off. Plus, you could always put the cat back if necessary.
 

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Thanks for the info.

The reason I asked is because I seem to remember the Cat having flanges that are bolted in place. I can't veryify that right now because I'm in Thailand. But if it is then it would be easier to get something made to replace than to hacksaw everything off. Plus, you could always put the cat back if necessary.
Off topic, but has the engine in your truck been swapped ? Didn't think the 53 block was until 98.:confused013:
 

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I don't know if it was swapped or not. Bought it second hand through a used car dealer and he got it from an auction site.

This could be a very late 97 truck. But at 166k it doesn't burn one drop of oil, the oil stays very clean until a couple thousand miles on the oil change, I get 21-24 mpg up here at high altitude running up and down the mountains. I got 28 mpg driving down to Phoenix from Flagstaff and 25 mpg while running around town in Phoenix. So maybe it was swapped.

Is there any way to tell?? The previous owner hadn't done much of anything else because I've replaced the pitman and idler arms, u-joints and center bearing. And a few other things.
 

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I guess the only way to tell would be if the vin # was stamped in the engine block. Not sure if dodge still does this or not. I'd be leaning twoards no since they are cummins motors.
 

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Does anyone have a Cat for a 04.5 they wanna get rid of?
 

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My thoughts...
94 on, cat and muffler required to be legal and removal is a federal no no regardless if they have road checks.
My answer is to empty the cat (and yes, the ends are two different sizes), find a low resistance muffler, and weld the system together. That way, IF you are ever checked, both devices are in place. If you fail the test, oh well...
 
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