Catalytic conv. failure


A catyltic converter uses a catalyst to convert three harmful compounds in car exhaust into harmless compounds.
The compounds are: hydrocarbons (in the form of unburned gasoline), carbon monoxide (formed by the combustion of gasoline) and nitrogen oxides (created when the heat in the engine forces nitrogen in the air to combine with oxygen).

In a catalytic converter, the catalyst (in the form of platinum and palladium) is coated onto a ceramic honeycomb or ceramic beads that are housed in a muffler-like package attached to the exhaust pipe. The catalyst helps to convert carbon monoxide into carbon dioxide. It converts the hydrocarbons into carbon dioxide and water. It also converts the nitrogen oxides back into nitrogen and oxygen.

Reasons for a converter failure
A catalytic converter will rarely fail without a problem or malfunction occurring somewhere in the emission system in front of the converter. It is important to determine what caused the converter to fail, so that the problem can be fixed and to prevent a recurrence of the failure. It can be difficult to determine exactly what caused a catalytic converter to fail, but the following failure descriptions will help narrow down your search for the malfunction.

Converter Meltdown:

This is an example of a converter meltdown. The converter was super-heated due to a raw fuel condition in the exhaust flow. The excess unburned fuel ignited when it struck the hot ceramic catalyst and drove the temperature far above normal operating condition of the converter. The ceramic catalyst is unable to withstand the extremely high temperature and begins to melt. The ceramic collapses and the converter is destroyed. The melted ceramic may block the exhaust flow and cause additional damage to the engine. A converter glowing red-hot or evidence of heat discoloration confirm this situation.

The too-rich condition that led to this converter melt down could be the result of a number of malfunctions including faulty oxygen sensor, an incorrect fuel mixture, worn spark plugs or plug wires, a faulty check valve, incorrect ignition timing, sticking float, faulty injectors or other ignition malfunctions.

Carbon Deposits:

This is an example of a converter with carbon deposits in the ceramic catalyst. This is usually a result of oil or antifreeze entering the exhaust system or a too rich fuel mixture. The heavy carbon deposit clogs the converter and reduces exhaust flow. This increases backpressure and causes the entire exhaust system to heat up. The heat backs up into the engine compartment and may result in a number of heat related engine problems.

Mild ceramic scoring may do less damage to engine components but it may seriously affect the converter's ability to reduce harmful emissions. It could easily cause a vehicle to fail an emission test.

Carbon deposits may be the result of faulty valves, worn piston rings, worn or leaking gaskets or lead in the fuel.

Catalyst Fracture:

This is an example of a catalyst fracture. The ceramic became loose, cracked and began to break down. The pieces began to obstruct flow, creating backpressure and increasing the heat in the exhaust system. There is evidence of partial meltdown in this example due to overheating.

The initial cause for this damage could have been road debris striking the converter based on evidence of impact on the converter shell. In some cases, if the protective mat that holds the catalyst in place is directly exposed to exhaust gasses; it could deteriorate and allow the catalyst to fracture. Our protective mat is shielded from direct exposure by our recessed dual cavity body and holds the catalyst firmly in place.

If a vehicle caused the OEM catalytic converter to fail, it could cause the NEW CONVERTER to fail as well.

Thanks to Patrick B.
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