How to clean the cat?

[DennisG01]

I've seen posts of numerous members talking about having the cat cleaned out. With 72K miles, is this something I should look into? And, what's the easiest way to do it? If it matters, I only get a good amount of black smoke under hard acceleration. By the way, what's the other thing that's inline with the exhaust? When I look at my exhaust, I see the muffler, the cat and then something else...

[HowieE]

The third object might be a resonator but I am not sure.
As for the cat just take in down and use a piece of pipe, 3/4in., and a hammer. It will just brake up and fall out with some help. Use a good resperator.

[Cowracer]

Bear in mind that there are Legal, Policital, Ethical, and possibly Religious issues to deal with in gutting a cat. Some states are more anal-retentive about cats on diesels than others.

In Missouri (for now) the only thing that can fail an diesel exhaust is leaks. I could be blowing Kingsford Charcoal Briquettes out the tailpipe, and they can't say anything about it.

Check you local laws first.

[MTTwister]

After my road trip in May, I'm thinkng of gutting the Cat and leaving it in-line, for show and tell, when I move to a state that has the emission testing. .

If it primarily catches soot, and the cure is to blow it out, seems to me it's a big hinderance in passing the 'emission' tests, as that's whats gonna be in their face when ya have to do the 'spike' test or whatever they call it.

[sturgeon-phish]

To remove the cat, I sawzalled the pipe about 3" back from the cat pipe to the exhaust, unbolted the cat from the down pipe. Rebar and hammer. It's ceramic and will break out. There is also a paper like stuff that is between the ceramic stuff and the cat shell. Poke around till everything is out. Bought a piece of 3" pipe cut about 10" long and slid it over the exhaust, put the cat into place I replaced the gasket between the crinkle downpipe and the cat, then socked the 10" piece of pipe over the end of the cat and clamped the piece on the cat and the exhaust. Easy, big improvement cheap!

[DennisG01]

Sorry, I should have been more specific. Although getting rid of the cat all together is something I am contemplating, I am wondering if it can get clogged up with soot and occasionally needs to cleaned out - like a fireplace chimney?

[gmctd]

It is an 'oxidizing converter', where soot and ash are cremated by high temperature exhaust gasses.
The 'soot trap' tends to clog up in trucks used for around-town only.

Best way to 'blow' one out is to do some heavy towing or hauling at highway speeds, a hundred miles or so, keeping the clay honeycomb hot enough to perform it's assigned task.

Make sure your air filter is clean, to provide proper oxygen\fuel mix to allow oxidation to occur.

Blowin' black smoke ain't gonna help! ;)

[tom.mcinerney]

A year ago i happened on a Canadian mining website which described routinely flushing out the cats used on compressors and traction engines (I believe steam-cleaning is alternated with soaking in diesel fuel). At the time i had hopes of rejuvenating our cats similarly. I now think the devices that are flushed out feature a different design technology than those used on the vehicles in this forum. My guess is that they are a metallic mesh, rather than our porous ceramic .
So gmctd's advice above is probably the ticket.
I would hazard that the results might be improved by injecting oxygen gas into the exhaust stream...but that would probably blow up the truck at the same time.
Impressive research, development, and field work is in progress cleaning up diesel exhaust. The Bush administration is moving forward with plans to require all diesel fuel in the USA to be free of most of it's sulfur contamination in a few years. The price will rise about $.08/Gal . Petroleum from Texas, the Gulf of Mexico, and Venezuela has a lot of sulfur.
Good results can be obtained with advanced catalysts iff 1)fuel less than 30ppm sulfur, 2)the exhaust temp remains over 275*C a third of time, 3)the engine's consumption of lubricant isn't excessive.
Some current production model cats are designed to be refreshed on a test stand with a heater and fresh air blower.
Of possible interest:
<www.dieselforum.org>
<http://www.dieselforum.org/retrofit/technology.html>
<http://www.epa.gov/otaq/retrofit/retroverifiedlist.htm>
<http://www.dieselforum.org/retrofit/contact.html>
<http://www.epa.gov/otaq/retrofit/techlist-ecs.htm>

[C.K. Piquup]

The problem with cleaning these cats is the ceramic becomes brittle.Any chipping,flaking,or breaking reduces effectiveness which then promotes more rapid clogging.Learned by experience(wood stove).Diesels show their emmsions more,yet pollute nowhere near what the bellyacher behind you is driving.The only truely(by law)ethical thing to do is replace with new.Big trucks get spot-checked for opague values,not us yet.Right??My state`s not testing our diesels at all,yet.See my crossed fingers?When they do I`ll have to yank the biggest 4" one from a dumpster,gut it,and fit `er in.Not sure what to do about HO 4911 & non-wastegated turbo.Any suggestions?Orange triangle instead of rectangular thing w/numbers and call it a tractor?

[Turbine Doc]

Cat Test pipe/offroad exhaust

I could not find someone who would build me one so I made one for when I off road.

I took the old crinkle down pipe flange knocked out the studs, cut off the crinkley part, welded a piece of stainless flex exhaust ala JC Whitney & Co. to the front end to connect to the turbo downpipe.

On the aft end used a stainless wrap around clamp to connect to the muffler inlet pipe, and saved the cat to swap back and forth ;) when I'm returning to on road use.

[ttpost]

i tie mines legs together, usually get scratched,rub it down with flea and tick spray. then i tie it to the deck.
next step is to take a 3200 psi pressure washer and spray it down.
next step
tie a knife to a stick and cut it loose
next step
run like hell :D

[MTTwister]

HowieE and Jim.. When the cat is gutted, does it act as a resonator? Amplyfing exhaust noise in the cab?

Jim - like your idea. How easy is it to get that pig outa there? Looks like a kinda tight squeeze to me. Did you use Band clamps, or regular exhaust 'bolt' clamps? Would you come over and do mine? smile.gif

[Turbine Doc]

MTT,

I'm not Howie or Jim, but with a Sawzall all things are possibe if you have never used one, you will hit yorself in the head like the "Wow I coulda had a V-8" commercial, they are just plain handy, that is what I cut mine with. I recommend the wrap around stainless band clamps as it doesn't put a crimp in the pipe like a std "muffler clamp".

If you are in some place that looks for a cat,
I've seen where others after knocking out the guts run straight pipe thru the shell to prevent it acting as a resonator & maintain smooth flow.

This is a little more work, hard to find someone that will do this for fear of legal ramifications, plus I'm not sure if really necessary.

Of course since this is in violation of many laws federal & local no one here is advocating you do that; or if you must, only run configured this way "off road".

[sturgeon-phish]

After cutting the pipe and unbolting the flange, pipe hanger too I think, it wiggles out pretty easy. There was a slight increase in exhaust noise. It will let you hear the turbo, which only whets your appetite for a mandrel bent 3.5" system!!!
A sawzall is a tool in the catagory of when this one breaks it is immediatly replaced.
As far as helping, I'm booked this weekend.

[gmctd]

Excellent post, ttpost - welcome to the club. :D

As you may have noticed, I only post for the humor, throwing in little informational bits just to keep folks' interest from flagging. ;)

Keep 'em coming - leave 'em laffing!

[ttpost]

gmctcd, i have read all your replies, deciphering all the information you have given me has been a great learning experience and i would like to thank you, and all the others, ( i feel like i just won an award :D i have been battling one thing after another,bad rebuilt computer. tranny, vacuum pump, bad vssb, several items all non related but related, is driving me nuts.

oh yeah irs said i owed em 20,000$ and audited me,the a- holes made me spend 1.5 weeks of my time going over receipts, when it was all said an done i owed them $150.00 i wonder how much they spent to get that 150.00 hmmm

now i am looking forward to cruising around in my truck tommorrow and just driving.

i dont know what you do for a living but you are very knowledgeable and i do appreciate your time and the others on the forum.

its been nice just to have a place to go, and see i am not the only one fighting with a vehicle

i will be around for a long time, and will help out where i can.

[Spindrift]

MTT,

I'm certainly no HowieE (sometimes wish I was). I revised the interior architecture of my cat and then I cut a 4" hole on either side. Ran my 4" pipe straight thru. My Magnaflow is the flow-thru design as well. No resonation and boy, does she sound purdy.

[MTTwister]

Looks like I'll get to throw more money into the Pit after this trip - and the bill's clear! :D

"Cat Back" exhaust, upgraded "Fan", check out Glow Plugs - little more white smoke in the AM than I'm used to seeing, and uhhh, other "must haves".

Oh, the GM place re-did my front seal under warranty on a SAT am! Acutally looks like the "slinger' is aligned with the housing this time. Nice Day here, too. ( X-ref another thread - but what the heck ) .

[HowieE]

I forgot to mention the steps I had taken before I gutted the cat.
I had had an exhaust brake installed and in doing so I had the Cat flanged at both ends and relocated behind the exhaust brake. This was done for 2 reasons. It placed the exhaust brake closest to the engine in the system insuring no leaks when it was in operation. In relocating the Cat with it flanged at both end it allowed me to remove it when and were I wanted while retaining the image to those who might like to look under the truck.
There is No discernable change in the exhaust sound with or without Guts.
A more interesting question would be the change in backpressure that removeal may produce. I had not taken detailed boost pressure readind before and after so that information was lost, but I have to assume it was very positive.