Cleaning Catalytic Converters

[Matthew Jeschke]

I got a small project with a friend. He is throwing catalectic converter code P420, if memory serves me right. His symptoms also seem to align with a plugged cat. Not sure we want to delete them as I've found backpressure is highly tuned on modern vehicles. I got WAY worse power and gas mileage on my truck w/o the full exhaust hooked up. Of course we could replace the system but I'm one for fixing / rebuilding if there's a way.

I see they sell this stuff now CataClean... Appears to be Acetone with gas, and couple other additives like Xylene / octane booster:

https://seattleautomotive.com/files/SDS/12007 cataclean.pdf

I know the computer has a Catalectic converter routine to keep it from overheating and carboning up by running a really rich fuel mixture aka Cat Over Temp / COT. Somebody else said to add a gallon lacquer thinner to your tank and drive the car around. Kind of makes me think of it running rich? Little worried if that eats up seals in the pump though.

Curious what other people have done for a dirty cat. I have heard two cycle oil in the gas and or ATF helps with injectors. What about a cocktail of lacquer thinner, seafoam, octane booster, and maybe a touch of ATF to reduce risk of drying out pump?

Any suggestions appreciated.

 

[Tonyrodz]

That CataClean is hit or miss. I was having problems with the cats in my van and someone suggested to try it--it worked for them. Didn't work for me. I just gutted it instead of replacing it. Sorry, no words of wisdom, just wanted to give you a heads up about the CataClean.

 

[Matthew Jeschke]

Yeah kind of what I thought. If you have big chunks in cats then there's no sense in cleaning them but no way to easily tell unless they get pulled. I turned off COTs in my tune so maybe worth running a tank every now and again with a catalectic converter cocktail myself. That CataClean seems to be a bit spendy though.

Did you notice a difference in fuel mileage? I assume converters do very little to restrict / change exhaust flow. Unlike a muffler with baffles?

 

[Tonyrodz]

Yeah kind of what I thought. If you have big chunks in cats then there's no sense in cleaning them but no way to easily tell unless they get pulled. I turned off COTs in my tune so maybe worth running a tank every now and again with a catalectic converter cocktail myself. That CataClean seems to be a bit spendy though.

Did you notice a difference in fuel mileage? I assume converters do very little to restrict / change exhaust flow. Unlike a muffler with baffles?

I wish I paid attention to the gas mileage. It's a pig on gas, so I never did. It's a 2500 with the 4l80, and it only has the 4.8. I pulled alot of stuff around since it was my work van and I was mobile.

 

[15burban]

If you have a welder it's not that expensive to buy a universal cat converter that fits your dimensions and weld it in. I've never tried them but ebay has some really cheap ones. When the converter clogged up on my Pontiac I found a magnaflow one that had the same dimensions and welded it in place. Was under $100 at the time if I remember correctly (8-10 years ago).

 

[Tonyrodz]

If you have a welder it's not that expensive to buy a universal cat converter that fits your dimensions and weld it in. I've never tried them but ebay has some really cheap ones. When the converter clogged up on my Pontiac I found a magnaflow one that had the same dimensions and welded it in place. Was under $100 at the time if I remember correctly (8-10 years ago).

Did it last? I've heard aftermarket cats don't last very long.

 

[15burban]

Did it last? I've heard aftermarket cats don't last very long.

I still have the magnflow on it and no problems so far. I'd have to look through my notes on when I put it on. I'm pretty sure I put it on around 100k and it's still going with 263k on it now. No check engine lights either. Now the ebay ones for dirt cheap I doubt would last long but a guy might get lucky

 

[Matthew Jeschke]

I don't have a welder. Really just looking for cleaning ideas here. I've gone that route before with good success however, I want to know if anybody has tried cleaning the cats.

 

[nonickatall]

I have cleaned catalytic converters many times.

The problem is also that the catalytic converter gets clogged from the front with soot particles and other dust.

You don't need any cleaning fluid for it.

The prerequisite for cleaning the catalytic converter is, as already correctly stated, that the catalytic converter is not crumbled.

You have to remove the catalytic converter and have to be lucky that you can look inside the respective catalytic converter.

There are stupid cats that have a curved pipe at the front that you can't reach.

I don't know what it's like with our cars. If you can look into the catalytic converter from the front, then it makes sense to put a little cleaning agent in the front. You can use normal cold cleaner.

It's just a matter of loosening the whole thing from the front on the surface. You can also carefully brush the element from the front with a brush. You can also clean the element from the front with a high-pressure cleaner if you're good at it.

But you have to be careful not to use a sharp nozzle and too much pressure and destroy the element.

Then you simply rinse the catalytic converter from behind with water.

You have to somehow connect a hose and let a lot of water flow through it so that the particles in the small tubes are flushed out.

I've had very good experiences with this.

I can't imagine any additives for the tank that work well, because they are injected into the cylinder, burn and are then passed through the catalytic converter as exhaust gas.

What kind of miracle cure is that supposed to be that the particles that hang in front of the catalytic converter are dissolved in such a way that they become so small that they can disappear from the exhaust through the narrow channels of the catalytic converter?

According to my technical understanding, this is not possible.

By the way, I haven't had any bad experiences with the aftermarket cats so far.

I passed the emissions test, which is very strict in Germany, and the catalytic converters lasted a long time.

Of course, if you have an engine that previously destroyed the old catalytic converter due to problems such as extreme oil consumption, a retrofit catalytic converter will not last long as well.

 

[Matthew Jeschke]

Ah cool. May still try a additive cocktail. Actually, you typically have some gas in the exhaust stream that doesn't get burnt. I presume if the cats get too hot then carbon can build up/ soot if not flushed out w/ a solvent such as gasoline in the COT routine the PCM runs. Don't take my word for it, I'm not a chemist though.

How much solvent it takes to pump through the engine to get to the exhaust to do a thoughough cleaning maybe somewhat limits its effectiveness? Also too much solvent can be bad on cylinder walls from what I understand, but probably okay to do once in a while? Just thinking out loud.

I referred him to an exhaust shop, they could probably just weld in some new aftermarket cats. I think he also bought that cataclean. I'd say if it was a GMT truck we'd just drop the exhaust but it's a AWD Chrysler 300. The thought of doing that makes me want to cry. It's packaged tight on that thing.