How-To: Replace Catalytic Converters and a Muffler on a Land Rover Discovery

Marc Olivares provides this how-to guide on replacing the muffler and catalytic converters on his 1999 Discovery.  It starts:

PREFACE:

My 1999 Discovery recently logged a P0420 code for catalyst inefficiency. Since I routinely used my catalytic converters as rock sliders, I knew this would be an inevitable repair. What I hadn't anticipated was the outrageous cost for a replacement Y-pipe. As I researched, I found that a new Y-pipe ranged in price from the mid 500's to over a $1000. Since my beloved Discovery is getting on in age, I couldn't see spending over $1000 on exhaust work, so, I began exploring the option of universal weld-in converters.

CATALYTIC CONVERTER OPTIONS:

Selecting a universal converter starts by determining the vehicles engine size, the converter type (2-way, 3-way, or 3-way w/air), and the vehicles test weight. In addition, the inlet and out pipe size also needs to be determined. For more information on how catalytic converters work, check these sites:BearRiverConverters.com
BearRiverConverters.com- Catalytic Converter Theory-PDFCar-Sound.com
Catalytic Converter WikiHowstuffworks.com
The Land Rover Discovery series 1 came with a Y-pipe that has roughly a 2-1/8th outer pipe diameter. If the method described below is used, the selected converter must have meet the following criteria:

Have a minimum of a 5500 lb rating3-way converter style
2-1/4" inlet and outletWidth between 4" and 4-1/2"
Height between 6" and 6-1/2"Overall length between 13" and 16"

 

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