Can you clean a catalytic converter?

[djcdmv]

Anyone out there know if catalytic converters can be cleaned? Saw some cleaner on amazon.com, but it had mixed reviews. Can you blow it out backwards with compressed air or vacuum it out? Thanks in advance?

[Nostril Cheese]

It wont work.

[redridge]

What are you trying to achieve?

[kerthunk]

You could always ram a big stick through it and knock out all that honey-comb looking metal stuff. May even gain a few HP due to the reduced back pressure.

In all seriousness, I don't think there is any kind of effective cleaning you can do to it.

[HawgRyder]

I'm not sure you understand the word "catalylist".
It refers to the chemical reaction of one substance on another.
So....when the catalyst works...it is used up....no amount of "blowing" is going to replace the used up substance.
Converters use paladium (expensive metal) inside...that is why they are expensive to replace.
Bob

[chococrazy]

You can try
Fixing Bad Catalytic Converters With Inefficiency Code P0420 - YouTube

I don't think you're trying to so much as replenish a used catalyst (which should be chemically unchanged), but trying to expose new parts of the paladium that may have been covered and or clogged over rendering them useless..

[djcdmv]

Thanks for all the replies and links. To explain better, I dropped the cat and tried the suggestion in Wayne's book to shine a light through one end. I'm unable to see any light coming through the other end. I thought this meant it was clogged. I did buy a cat delete, but I'm not thrilled with the extensive smoke I am getting after the car warms up and am considering switching back. It didn't smoke this bad right before removing the cat last weekend... Could a new O2 sensor solve the smoking problem? I will start a new thread with that question now.

[E Sully]

If the smoke is from the wrong fuel air mixture an o2 sensor might help, but not if it is oil smoke. The catalytic convertor would have been cleaning up the smoke from oil burning, masking the symptoms of perhaps worn valve guides or rings.

[1990C4S]

Outside yes. Inside no.

[James Brown]

hummmm, M491, bad cat, better sell it to me, no need for a cat in washington state. It will have a good home for it's waning years.

[HawgRyder]

Did you remove the power from the ECU to get it to reset after removal of converter?
The chip in the ECU only comes into effect when it first starts up (power up) and from then on it's learning process to account for clogged jets, bad plugs, altitude, etc.
So...if the ECU still thinks the converter is there...it may be running rich or lean to compensate.
Bob

[ejp]

Originally Posted by chococrazy

You can try
Fixing Bad Catalytic Converters With Inefficiency Code P0420 - YouTube

I don't think you're trying to so much as replenish a used catalyst (which should be chemically unchanged), but trying to expose new parts of the paladium that may have been covered and or clogged over rendering them useless..

Let me know how putting pure lacquer thinner in your gas tank and running it through your fuel system goes. Something tells me that this is a horrible, horrible idea. I'll be the last one to try it.

[aigel]

Originally Posted by HawgRyder

I'm not sure you understand the word "catalylist".
It refers to the chemical reaction of one substance on another.
So....when the catalyst works...it is used up....no amount of "blowing" is going to replace the used up substance.
Converters use paladium (expensive metal) inside...that is why they are expensive to replace.
Bob

Generally the catalyst is not used up. I.e. the palladium is still there 200k miles later.

Catalysis - Wikipedia, the free encyclopedia

Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself.

With the OP describing a very smoky running engine (burning oil) or even rich running engine (excess fuel into the exhaust) his cat may have gotten clogged or overheated.

Catalytic Converter Failure

Catalytic converter failures typically fall into one of four categories:
1. Thermal failure (overheating)
2. Plugged substrate
3. Thermal shock
4. Physical damage

Thermal failure is most often caused when excessive raw fuel comes into contact with the catalyst, and "burns" in the converter instead of in the engine. The high quantity of fuel generates temperatures well in excess of the capacity of the converter, causing meltdown of the ceramic monolith. The melted ceramic could block the exhaust path, leading to a significant loss of engine power. Visible symptoms include heat-related discoloration of the converter shell.

Potential causes of thermal failure include: misfire, malfunctioning oxygen sensor, fuel delivery issue, improper choke setting/operation, and ECU malfunction.
A plugged or contaminated substrate can be the result of an overly rich air/fuel mixture, radiator sealant, and oil or antifreeze entering the exhaust flow. The resultant carbon deposits restrict the operation - and ultimately the flow characteristics - of the converter by coating the unit's reactive surface. This degrades the converter's ability to perform its chemical conversion process, leading to potentially illegal levels of HC, CO, and NOx.

Root causes of this problem are a malfunctioning O2 sensor, plugged or inoperable fuel injectors, piston blow-by, leaking head gasket, broken or frozen choke or carburetor float, excessive cranking time, and repeated incidences of running out of gas.

Thermal shock occurs when a fully heated converter suddenly is "cold-quenched," such as coming into contact with snqw or ice. This leads to sudden contraction of the converter housing, which can cause cracks and disintegration of the ceramic substrate. Symptoms include a "rattling'' sound when the converter is tapped with a fist or mallet (monolith-type converters only).

Physical damage, caused by running over road debris, collisions and other impacts, is usually easy to diagnose. This type of damage can break up the ceramic substrate or cause restriction that changes the flow characteristics of the converter or impacts the efficiency of the catalyst.

With all this said, I'd address the smoking first, then get a good used unit and install it and be done.

G

[Bob Kontak]

Originally Posted by ejp

Let me know how putting pure lacquer thinner in your gas tank and running it through your fuel system goes. Something tells me that this is a horrible, horrible idea. I'll be the last one to try it.

Why do you think that?

Muratic acid may not be a good choice but lacquer thinner is just fine. Yes I did it.

Our cats are easy to get off. I would just dump them in the wash tub like the video shows.

I did the lacquer thinner because the car had the cats as part of the exhaust manifolds (straight six) and I was not able to see thru them. Ended up being the downstream O2 sensor throwing the converter code.

I researched plenty before doing it.

Also it's not pure lacquer thinner - it is diluted plenty in the youtube video.

[m110]

Just buy a used one that works..they are cheap on this board. A brand new DEC unit welded in line will be $5-600. Once a CAT is clogged (and there are alternatives) just move on. They do wear out and if yours is so clogged that you can't see through it I would dump it.

[PCA7GGR]

In some cases, a 3.2 will pass smog (and the visual) with a gutted cat.

[chococrazy]

People pour transmission fluid into gas tanks. Lacquer thinner is probably just as flammable as gasoline but may have less "energy" persay. Now in terms of seals and stuff I wouldn't pour muriatic acid as bob said but wouldn't worry to much over a little lacquer thinner. TBH some of the gas people start their car on after it's been sitting for years is probably worse for the car.
I've knocked out a few cats you'll want a big bucket on hand and possibly a breathing mask/respirator if you go that route.

[PCA7GGR]

air chisel does the trick

[ejp]

Originally Posted by Bob Kontak

Why do you think that?

Muratic acid may not be a good choice but lacquer thinner is just fine. Yes I did it.

Our cats are easy to get off. I would just dump them in the wash tub like the video shows.

I did the lacquer thinner because the car had the cats as part of the exhaust manifolds (straight six) and I was not able to see thru them. Ended up being the downstream O2 sensor throwing the converter code.

I researched plenty before doing it.

Also it's not pure lacquer thinner - it is diluted plenty in the youtube video.

I am by no means an expert, so take anything that I suggest with a grain of salt. However, it seems to me that there are plenty of things that might not do well with laquer thinner in a fuel injection system, especially if unburned thinner will pass through them. The stuff that comes to mind would be o-rings & seals on injectors and O2 sensors (which are notoriously sensitive). I really could be nuts on this, but it just doesn't sound right to me.

Removing and cleaning sounds a bit less risky to me.

[djcdmv]

Soaked the removed cat in straight turpentine overnight... no luck. Luckily found a used cat here on Pelican to replace it with.