Engine/Transmission (1994 - 1998) Gutting the Cat.

[rlittle]

I would like to drop my EGT when I tow as they are going into the 900 post turbo level when I tow on hills. I have heard that gutting the cat out will help to drop the temps. I can not remove the cat as our inspection people check to see if there is one on the truck when they do the yearly check.

The turck has about 75K on it, auto, has a #8 plate in the pump, and a K&N air filter. Trailer it a 5000 pound fifthwheel.

If this will help with the temps when I am towing any suggestions on how to gut the cat after I get it out.

Thanks

Rollie

 

[kchristopher]

If it were me, I'd pull it and the muffler off the truck and put it somewhere easy to work. Using a cut-off wheel, cut three sides of a square in the top (bed-facing) side. Pry the 'door' up and then find your air hammer/chisel. It takes a while, I would imagine, as this stuff is tough. It is a long way back in there from the pipe ends, and I don't know of an extension long enough that works with an air-hammer. When done, weld up the door.



Try to refrain from using the air-hammer constantly for long periods of time. I used it once for 25-30 minutes straight and now my middle finger is in a splint due to 'soft tissue damage'. Didn't hurt until the next morning.

 

[Boldt's Wagon]

Buy a long drill bit (18 inches?) and drill it out from the 4 inch end.

 

[Todd G]

Step 1: Remove cat-with-guts from truck



Step 2: Stand up cat and place on heavy piece of wood



Step 3: Use heavy object (I used the handle off my floor jack) and beat at the guts. This part took a while. Don't breath dust.



Step 4: Replace gutless cat







I went through emmissions a few months ago and watched carefully as they ran test. They did not check for cat. I asked them when it was over and they said they do. Right.

 

[98rammer]

btw, from my experience... . i used a crowcar/prybar/pinchbar (whatever you want to call it) with a really big hammer. it took a lot, but once i broke through the center, then the rest of it started to collapse.

 

[grtescpa]

Originally posted by rlittle

I would like to drop my EGT when I tow as they are going into the 900 post turbo level when I tow on hills. I have heard that gutting the cat out will help to drop the temps. I can not remove the cat as our inspection people check to see if there is one on the truck when they do the yearly check.

The turck has about 75K on it, auto, has a #8 plate in the pump, and a K&N air filter. Trailer it a 5000 pound fifthwheel.

If this will help with the temps when I am towing any suggestions on how to gut the cat after I get it out.

Thanks

Rollie

Be careful when you remove the material inside the cat. Do not inhale that stuff. It causes cancer.

 

[SlyBones]

I have heard a hollow cat can sound like crap. Creates resonance and adds drone, or something to this extent. It might be of benefit to see from members how the exhaust note changes after installing a hollow cat.



I just removed mine, and the inspection people so far have not checked.



Depending on your exhaust size, gut the cat as described and then weld a 4" pipe thru the middle of it. So on the outside it looks like a cat. On the inside its a straight exhaust pipe, no hollow chamber. -- Also makes it sound solid it they happen to tap on it. I heard a story once about the inspection police using a hammer and listening to see if it sounded hollow.

 

[Dennis Garrett]

Once you get it off the truck, stand it on end, and get one of those 18" long shaft 1" blade or paddle type wood borers, (The cheap kind) put it in an electric drill, & go to it. This stuff drills out easily, but you will beat on it all day trying to break it out. Drill from both ends, & from all angles, and you'll get most of it, then break the rest of it out with a piece of 1" pipe or what ever you want to use. It's bonded to the sides of the casing, & you can't drill all of it. but by that point, it will break out easily.

 

[illflem]

The way Dennis just described is the best. In my opinion trucks with gutted cats sound funky, sort of a tinny rattle. If I had to deal with inspections I'd just put the cat back on for inspections and use a straight pipe the rest of the time. Most likely if you are caught without a cat they will just tell you to come back when it's fixed, chances are they'll never look to see that it's missing.

 

[98rammer]

yeah, it does sound wierd... . maybe i'll do the pipe insert with some stitch welding. (have any of you heard the difference with a pipe in place or the pipe inside the cat as compared to the hollow cat?)

 

[Todd G]

Mine sounded the same after the feline operation

 

[RJ2]

Does eliminating the cat cause a drone? I have the mopar filler pipe but have been hesitating because of threads on getting a drone going without the cat.

 

[illflem]

RJ, sure you're not confusing the cat with a 24 valve resonator? After straight piping cats they sound a little different at idle but nothing to really bug or concern me. Definitely not a drone though.

 

[SlyBones]

RJ2, I had a BD 4" catback when I installed the DC test pipe. Still had a 3" downpipe back to the cat, at that time. I interior sound did not change much at all. Hardly notice. Exterior sound improved nicely. The catback added very little of that 4" sound trucks have. I was always disappointed with just the catback. Removed the cat and got both the sound and egt reduction. Ran with the 3" - 4" combo for quite a while. Finally went to a full 4" when I had the BD 4" remote mount ebrake installed.

 

[Kirwin]

Another way

Although its more expensive, the late model resonators look and fit exactly like the 94-98 cats and unless someone really looks they can't tell them apart without disassembly and a peek inside!

 

[Sleeper]

I had a very well known local personality use the Sleepy Hauler as a test horse. 4" pipe straight through, welded up nicely, looks original, sounds great.





Sleeper

 

[firemanmarc]

I took my cat off and pounded guts out, then put 45 degree 4" elbow on it, exits right there. Excellent EGT's whole lot of sound!!!!!!! IT definitely makes all kinds of noise until 2000rpms, then mellows out. Would replacing it with a straight pipe instead of cat mellow the bellar out of it???? Thanks Marc

 

[-Alex-]

I know a guy who just ran 4" pipe straight through the gutted cat. Looks original, and no turbulence or drone.

 

[jwalton]

Anybody know what exactly is inside them that causes cancer. After i did mine i got sick but it may have been a coincidence. By the way the drill bit sounds like a great idea. Took me quite a while to beat it out with a horse shoe peg and a bfh. Can't wait to see the results

 

[illflem]

Platinum is the nasty in cats. Traces of it found in the polar ice caps have increased dramatically since cats have been required. Some environmentalists are wondering if the cure might be worse than the disease as far as cat platinum and smog are concerned.



Another bad component of a used cat is a high concentration of diesel soot which isn't poisonous in itself but rather is an irritant because the ultra fine particulates have very sharp jagged edges that don't agree with the inside of your lungs.