Clogged Catalytic Converter Options

[barterj]

Last summer the first catalytic converter melted and clogged the second one. I punched out the second and replaced the first one since that is the one with 2 oxygen sensors connected to it. Since I replaced the cat I've put about 20K miles on my car. The cat. melted and got clogged again.

Does anyone know any reason(s) why this is happening?
-220K miles (2.2L)
-Engine is running at normal temp, never over heats
-Doesn't burn hardly any oil, maybe half a quart every 3,000 miles.
-It is eating gas, though i think that was from the cat being clogged and it needing extra to keep the engine running under the increased back pressure from the clogged converter.

Here is a pic of what it looked like before I punched it out today

[stephen_lee]

id just replace it unless it already has been on the last 50 000 miles

"Normally, the lifetime of an unheated sensor is about 30,000 to 50,000 miles (50,000 to 80,000 km). Heated sensor lifetime is typically 100,000 miles (160,000 km). Failure of an unheated sensor is usually caused by the buildup of soot on the ceramic element, which lengthens its response time and may cause total loss of ability to sense oxygen. For heated sensors, normal deposits are burned off during operation and failure occurs due to catalyst depletion. The probe then tends to report lean mixture, the ECU enriches the mixture, the exhaust gets rich with carbon monoxide and hydrocarbons, and the fuel economy worsens."