I have a 2002 with the old 5.9 magnum drivetrain. On a recent camping I noticed a loss of power on the highway. At the same time my truck developed an exhaust leak at the flang of the manifold and y-pipe. I trying to locate the leak, I noticed that the Catalytic converter shell is completly broke at both ends and I can almost rotate it around. So I take it the cat has to be replaced. Someone told me that the cat might be getting bad/plugged and the extra pressure before the cat might have caused my exhaust leak. My question is the y-pipe comes down in a 2in pipe and then the two sides go into a 3 inch pipe that looks like it is right at the cat. So is the cat and the y-pipe all one part? In the service manual I downloaded, it looks like it is. My truck has only one cat and 2 O2 sensors, one before, off after. Any comments would be appreciated.

 

If all original it would be one piece from the manifold to the cat.

You can purchase just a cat and have it welded in or replace the entire thing, at a higher cost obviously.

 

I moved this to 2nd Gen where you WILL get solid confirmation about your exhaust. 2002 was the only 3rd Gen year for 5.9L gas

Most aftermarket replacements are 2-pieces.

 

absolutely the pressure from a clogged cat could have caused your exhaust leak.. especially if it was weak from rust and corrosion..

the Y and the cat are welded together.. you cut the cat out and weld a new one in..

dude, take this opportunity and rid yourself of the OE Y pipe.. that thing is choke central.. use a shop fabricated, or a JEGS or MagnaFlow offroad Y pipe.. and use a MagnaFlow High Flow cat in the place of the OE one.. you will thank yourself profusely.. your power will increase, especially @ 2k+ RPM.. your mileage will slightly bump (as much as 1mg), and there will be zero low end loss..

good luck dude!

 

I live in atlantic canada, and called local parts stores and I think they are trying to rip people off. Has anyone out there from canada ordered converters from JEGS or any other aftermarket parts supplier from the states? If so any issues gettting them shipped to canada? I got prices for universal cat replacements and they are almost the cost for an entire exhuast system from the states. Anyone have any comments?

 

Do you have emissions testing in your area? If you don't, just cut the cat out, and weld in a pipe.

If you do..... magnaflow makes some direct fit pieces that are good.

 

No emissions testins, but if I cut it out would I not get a CEL error from the rear O2 sensor?

 

Maybe.

You can get around that by using the 'non-fouler' trick. I do believe there is a DIY in the faq section regarding that.

 

I have a 98 with a 360. Took the cat off a few weeks ago when I ran true duals. Put the O2's right into the pipe. No check engine light yet

 

non-foulers on the rear O2s are the wat to go when no cats are used and custom tuning isnt cost effective or needed.