[brider]

I've wondered this for a long time, searched and didn't find an answer.

Can't imagine why the (2) would be different designs and shapes. What do they look like on the inside, anyway?

 

[90 red rover]

i have wondered the same thing. i guess i figured that it was an issue of one of mine went bad and was replaced at some point? maybe its a clearance thing?

 

[brider]

That's where I am right now, one or both are bad, but there's aftermarket universal units that have the correct length and inlet/outlet dia at a fraction of the LAnd Rover part, so why could I NOT use a universal unit at BOTH locations?

 

[76FJ55]

I had assumed it was a clrearance issue, but that is just speculation.

 

[belew]

Land Rover Workshop Manuals - Discovery II - Exhaust Emission Control System

"The two catalytic converters are shaped differently to allow sufficient clearance between the body and transmission,
but they remain functionally identical since they have the same volume and use the same active constituents."

 

[pazzo rover]

"so why could I NOT use a universal unit at BOTH locations"

You can. There is a decent write-up Under TECH >> Catalytic Converter...............

discoweb.org --

 

[brider]

Land Rover Workshop Manuals - Discovery II - Exhaust Emission Control System

"The two catalytic converters are shaped differently to allow sufficient clearance between the body and transmission,
but they remain functionally identical since they have the same volume and use the same active constituents."

THAT'S what I was looking for. But this passage caught my attention:

"CAUTION: If the engine is misfiring, it should be shut down immediately and the cause rectified. Failure to do
so will result in irreparable damage to the catalytic converter"

My engine had been mis-firing for a couple of thousand miles before I fixed it, and around that same time is when my cats began their incessant rattling.

Coincidence? They ARE 169k miles old, so maybe that mis-firing was just the straw that broke the camel's back.

 

[Racer X]

Misfiring usually means unburnt fuel in the exhaust.

This unburnt fuel will in turn burn in the catalytic converter, causing it to overheat and ultimately disintegrate and fail.

So, yeah, that probably killed your cat.

 

[Paul Grant]

Go to Summit Racing and look up Catco 6905 catalytic convertors. I've used them many times on various Range Rovers and Discovery's I've had over the years. They're cheap and fit either side. IIRC they offer two different lengths, 12" and 14." I recommend the 12" version for OBDII trucks (more room for the upstream and downstream bungs for the O2's) and the 14" for OBDI trucks.

 

[Racer X]

Go to Summit Racing and look up Catco 6905 catalytic convertors. I've used them many times on various Range Rovers and Discovery's I've had over the years. They're cheap and fit either side. IIRC they offer two different lengths, 12" and 14." I recommend the 12" version for OBDII trucks (more room for the upstream and downstream bungs for the O2's) and the 14" for OBDI trucks.

Good point, I ordered another 6905 for my truck before the June 1st ban went into effect here in NYS.