Hey guys, I have a 2000 Cherokee 4.0. Need to get a new front cat but it seems there are two different ones. Looks like a model split at 1/20/2000. My production date is 12/99 so my guess is I use a '99 cat? Anyone have info on this?

 

Your production date has nothing to do with the registered year, companies produce next model years as early as 6 months out from model year. The real difference between 99 and 00 is emissions, after 99 it went to Cali emissions but at the federal level.

Easiest way to tell what you actually have is to pop the hood, and if you see 2 cats/sensors within the exhaust manifold. Then there will be another O2 sensor after the manifold, and another after the rear most cat for a total of four

 

When there is a production split it has everything to do with it. It could have different parts before/after split, which seems to be the case for the front cats. It looks like before the production split it has 2 front cats with a longer pipe after they go into one pipe and no flange before rear cat. Post production split seems to have a short pipe where they go into one and a flange that connects to a curved pipe and then to the rear cat.

 

I have never been able to find an exhaust diagram for '00's made before 1/20/00.
I have tried to help a couple people over the years.
But have never really figured it out.
I ask them for pictures but they never really show me what I need to see.
And they never follow through on threads saying what they did buy to replace it.
The one thing I am fairly certain of is that all your exhaust is slip on and not flanges.
Now you did say front cat. So you do have the dual front cat and a rear cat?

 

Okay, here's the skinny. These XJs were made in 2 models, a Cali emissions one and a Federal emissions one. The Cali one was made for Cali and NY, who decided any NEW car sold in the state after 97 had to have Cali emissions. The Cali one has 2 precats on the 2 cast iron exhaust manifolds joined at a Y with a flange, an 02 before and after each cat, and a downstream cat that is NOT monitored. My 2000 XJ currently has no downstream cat because it fell off, but seems to run fine with just a muffler, although once in a while it will set a "cat efficiency" CEL after a hard high speed run.

The Federal system has one 02 in an exhaust downpipe and one after the cat underneath the floor. There may be other states that require Cali emissions as well, because things are constantly changing. The way things are changing ALL states may require this. IDK if the Federal emission systems use cast iron manifolds or not, but I believe all waste spark engines do. I also feel all that excessive heat is what causes the 0331 heads to crack. Just a hunch.

 

Yes dual cats in front and single rear. Two O2 sensors in exhaust manifold and two after front cats. The previous owner cut out rear cat and muffler and welded in straight pipes so I don't have stock exhaust to compare. From from my research it seems you are right and it needs cat without flanges.

 

So you pretty much have to buy a whole new exhaust?
Are you going to put it back to stock or still run without the rear cat?
Which is also referred to as a resonator here and there.
Cause here is something I always wondered about.
My CA Emissions '00, manufactured after 1/20/00 is all flanges.
Except the back of the muffler to the tail pipe.
So if you actually needed a whole new exhaust could you put an after 1/20/00 one on a '00 XJ made before that?
if you were willing to spend the money I don't see why not.

 

The 2 cats are not front and back but side by side. They are entirely in the exhaust manifold above the downpipe flange. Cat 1 is fed by cyls 1-2-3 and cat 2 is fed by cyls 4-5-6 . They are tough to see from above the engine but there is an o2 sensor above and below each cat. There are NO o2 sensors in the exhaust pipe after the flange by the transmission. The big oval can in front of the transfer case is a Resonator...hollow ish-no cat material inside. If you have a 2 piece manifold you have both those cats right under the intake man.. if you have a 331 head you have the new/ late model stuff. Its a bad picture of the exh manifold but those 2 big bulges are the CATS...there is nothing behind or further downstream

 

From my 2000 parts guide:

PIPE AND CONVERTER, Exhaust, To Manifold (2 cats up frront)
#52101 112AB 1 ER0 Use up to 1-20-00 Has a slip connection
#52101 112AD 1 ER0 Use after 1-20-00 has a flanged connection

CONVERTER, Catalytic (one in rear)
#52019 480AH 1 EP0 Federal,Europe II, After 1/20/00
52019 480AG 1 ER0 Federal,Europe II,Up to 1/20/00

 

Thanks this is what I was looking for.

 

I'm going to replace entire exhaust but needed to know which ones to order.

 

Most likely no you are not.
I couldn't find them.
Maybe you will have better luck.

 

Banks header, magnaflow front and rear cats and banks monster cat back.

 

I was talking about trying to find a factory part.

You do realize with a Magnaflow front cat it will most likely have a flange.
Then you will need the intermediates pipe and you will mostly likely have to go with Walker on that.
And that will have flanges at both ends too.
So basically if I am correct you will end up putting made after 1/20/00 exhaust on your Jeep.

 

When Ralph says it can't be found you should just give up while you're ahead, just saying....
(for all the hurt people this is a joke you're great relax)