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What Can B Used to Clean Catalytic Converters?

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M

Michael J.

Jedi Warrior
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If you have been following the string XJS V-12 High Fuel Consumption & Low Power, you would have seen that I pulled the secondary Catalytic Converters to see if they were obstructed.

There is a lot of carbon soot build up in the secondary cats. Not enough to clog them, but I am wondering if they are partly restricting the exhaust flow because of all the carbon from running so rich.

Has anyone ever cleaned out catalytic converters and what can you use to clean out soot? At over $300 apiece, I don't want to damage them while cleaning them out.
 
I have gutted them /ubbthreads/images/graemlins/devilgrin.gif hehehe
 
As far as I know, a cat cannot be cleaned chemically. But I suspect a good Italian tune-up and a nice long road trip will do the trick.
 
If there is no law against it where you are....Get rid of them....Or gut them.
 
Michael, To check on a cat clog, unhook the down pipes going to them and drive the car to see if it changes anything.
 
To my knowledge, the converters are not possible to clean but they can be gutted. (or replaced with a European down pipe).
 
Mike,

The Catalytic Converters are a matrix (Bed) of ceramic material which has been "Flame Sprayed" with either Platinum or Paladium. Both metals have a very black (Carbony) appearance when applied to the ceramic substrate.
If the cats are firing off then powdered carbon cannot survive in there.

To test if they are working, simply hook them back up (After doing John's test to see if they are plugged) take a couple of turns around the block then check to see the relative temperature of the cats. You don't need any special test equipment to do this.... Your hand will suffice as a thermometer... DO NOT TOUCH THE CATS!!! but by holding your hand a few centimeters away from the pipes and the cats you should be able to determine a marked difference between them. If you can't feel any difference your cats are probably dead.... Replace or Gut, your call.

/ubbthreads/images/graemlins/cheers.gif

Mike

BTW... There is nothing you can use to clean them (Other than the affore mentioned "Italien Tune-up"
 
YOu coud blow them out with compressed air, but it's probably not going to do much. Using chemicals is not reccomended. mildly sooty is not a big issue. Melted down is a problem.
The big thing is, what is causing them to soot up. Just throwing new cats under there is not fixing anything. You need to find the root cause of the rich condition, or new cats will just get clogged up in short order.
Short runs, or babying the car can be causes, as the cats never get up to operating temp to burn off the soot.
 
Lead, Sulfur, Phosphorus and Zinc are the main chemical deactivators of catalysts. Any lead poisining would not be from recent years as the concentration and availability have decrease in the last 15yrs to almost zero. Sulfur is in the fuel and new emissions laws will get it down to below 100ppm. Phosphorus and Zinc are in the oil as antiwear additives, so the more oil you burn the higher poisioning level.

All of these clog the catalyst sites of the Pt, Rh and Pd. The metal is still there but is covered up.

Lead - Hard to remove - very good adheision to catalyst

Sulfur - High temps will burn it off (italian tune up)

Phosphorus and Zinc - Hot oxalic acid pumped though the catalyst will remove the poisioning but the process is beyond most DYIers.

Replacing with an old used unit is almost as bad a removing it all together.
 
Thanks everyone for the suggestions and comments.

The Cats are 6 - 8 months old and light shines through from one end to the other. I did not find any evidence of mentdown, just a lot of soot from the running rich problem.
 
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