Dead Catalytists

Hi Neil,

found this, don't know if it helps or not. Causes of catalyst failure -

1) Carbon pollution, leading to a blockage of the catalyst. Too rich a fuel mixture and / or oil antifreeze entering the exhaust causes this. Carbon deposits initially restrict the operation of the catalyst by coating the available reactive surface. If the fault is allowed to continue the actual exhaust flow through the exhaust is restricted, leading to a reduction in engine power and eventually total blockage.

2) Converter melt-down. Usually caused by neat fuel entering the exhaust. Once this neat fuel enters the hot catalyst it ignites and superheats the catalyst and causes melt-down of the ceramic monolith. The melted ceramic may block the exhaust and the fault will show as above. Other signs are the converter glowing red and /or discoloration due to the heat generated on the other surfaces of the converter.

3) Internal fracture of the catalyst. This is usually caused by external / internal physical damage i.e. something hitting the exhaust, internal damage or the actual monolith coming loose internally. The most obvious signs of this fault are exhaust rattles / vibrations.

Catalytic converters are generally agreed to have a service life of between

50 - 100,000 miles but there are several factors, which will reduce this life drastically. These include:

Lead pollution

Engine ignition/fuelling faults

Vehicle use, short journey use prevents the converters from reaching operating temperature.

When Catalytic converters fail prematurely there is usually a reason for it and it is important that this fault is addressed before the replacement is fitted, to prevent the damage that will occur to the new unit. Converter faults take time to show, so it is possible to replace one and the vehicle will function OK, pass all emissions tests etc, but will still have the underlying fault, which will shorten the replacement service life.

Got the above from

Bob.

Cheers ;-)

Neil

found this, don't know if it helps or not. Causes of catalyst failure -

1) Carbon pollution, leading to a blockage of the catalyst. Too rich a fuel mixture and / or oil antifreeze entering the exhaust causes this. Carbon deposits initially restrict the operation of the catalyst by coating the available reactive surface. If the fault is allowed to continue the actual exhaust flow through the exhaust is restricted, leading to a reduction in engine power and eventually total blockage.

2) Converter melt-down. Usually caused by neat fuel entering the exhaust. Once this neat fuel enters the hot catalyst it ignites and superheats the catalyst and causes melt-down of the ceramic monolith. The melted ceramic may block the exhaust and the fault will show as above. Other signs are the converter glowing red and /or discoloration due to the heat generated on the other surfaces of the converter.

3) Internal fracture of the catalyst. This is usually caused by external / internal physical damage i.e. something hitting the exhaust, internal damage or the actual monolith coming loose internally. The most obvious signs of this fault are exhaust rattles / vibrations.

Catalytic converters are generally agreed to have a service life of between

50 - 100,000 miles but there are several factors, which will reduce this life drastically. These include:

Lead pollution

Engine ignition/fuelling faults

Vehicle use, short journey use prevents the converters from reaching operating temperature.

When Catalytic converters fail prematurely there is usually a reason for it and it is important that this fault is addressed before the replacement is fitted, to prevent the damage that will occur to the new unit. Converter faults take time to show, so it is possible to replace one and the vehicle will function OK, pass all emissions tests etc, but will still have the underlying fault, which will shorten the replacement service life.

Got the above from

Bob.