Catalytic Converter Heat Shield

[Rymanrph]

I have a serious heat problem.  The catalytic converter under the passenger floor board is cooking my interior.  It got hot enough to melt the carpet backing to the heat insulation I installed on the floor and transmission tunnel.  So, now I need to figure out some way of shielding the cat from the floor.  Obviously the barrier I put down on the interior wasn't enough, so I'd like to put something between the cat and the floor.  Was there a shield there from the factory?  

 

If there isn't a part that is supposed to go there, then I'll have to make something.  Can the cat be wrapped, or does it get too hot for that?  If I have to make my own heat shield, are there any recommendations for materials?

 

 

[HOrnbrod]

MJs and XJs never had one from the factory, but ZJs did. Perhaps you could adapt one of those or a shield from some other vehicle. Or do something like this:

 

[Rymanrph]

I was thinking about something like that, but I didn't know how hot the cat gets in comparison to what those wraps can take.  They are rated in two different temperatures - direct contact and indirect.  I might just buy a sheet of aluminum and build something to sit between the cat and floor.  It would probably be cheaper to go that route.

[ScottJeep]

Not sure the size cat you are working with.

 

But maybe something like this:

 

http://www.ebay.com/itm/Mopar-68064953AA-Catalytic-Converter-Heat-Shield-for-2007-2010-Ram-6-7L-Diesel-/311439973553?hash=item488344dcb1:g:GT4AAOSwHnFV7JnZ&vxp=mtr

 

My other thought was ceramic coating that section of the floorboard.

 

http://www.ebay.com/itm/Mopar-68064953AA-Catalytic-Converter-Heat-Shield-for-2007-2010-Ram-6-7L-Diesel-/311439973553?hash=item488344dcb1:g:GT4AAOSwHnFV7JnZ&vxp=mtr

 

But there is a definite cost difference between the two. 

[Rymanrph]

Not sure the size cat you are working with.

 

But maybe something like this:

 

http://www.ebay.com/itm/Mopar-68064953AA-Catalytic-Converter-Heat-Shield-for-2007-2010-Ram-6-7L-Diesel-/311439973553?hash=item488344dcb1:g:GT4AAOSwHnFV7JnZ&vxp=mtr

 

My other thought was ceramic coating that section of the floorboard.

 

http://www.ebay.com/itm/Mopar-68064953AA-Catalytic-Converter-Heat-Shield-for-2007-2010-Ram-6-7L-Diesel-/311439973553?hash=item488344dcb1:g:GT4AAOSwHnFV7JnZ&vxp=mtr

 

But there is a definite cost difference between the two. 

 

I got the same link twice, but after clicking on it, I saw this one too: http://www.ebay.com/itm/Mopar-68064953AA-Catalytic-Converter-Heat-Shield-for-2007-2010-Ram-6-7L-Diesel/291940007837?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D38530%26meid%3D00f83097c7414681a7f66a96c2532119%26pid%3D100005%26rk%3D1%26rkt%3D1%26sd%3D311439973553

 

Either of these might be a good option depending on the size, especially since it has the clamps integrated already.

[mikekaz1]

does NC require emissions still? why not just delete the cat.

[Rymanrph]

does NC require emissions still? why not just delete the cat.

 

It's not required for my truck because it's old enough, but I figure it's cheaper to add a heat shield than to pay someone to remove the cat and weld in a straight pipe.

[sinkrun]

If the cats that hot its time to get a new cat or delete it.

[Eagle]

If the cats that hot its time to get a new cat or delete it.

 

Agreed. If the cat is generating enough heat to melt the padding under your carpet, something is seriously wrong.

[Marine1Texas]

How close it to be able to generate that much heat? If it is sitting right next to the cab like less then 3 inch's heat can come off it, but not enough to do that, unless you have fuel burning in the cat. My cat (hollo) sits a cool 10 inch from the bottom of the cab, right at the level of the skid plate on transfer case.

 

A super lean mixture would make the cat hot, however fuel going in to the cat and igniting would make even more heat, at that point, the cat is no good anyway, all burnt out...

[HOrnbrod]

If the cats that hot its time to get a new cat or delete it.

 

You need one of these:

 

[jeepsouth]

 

If the cats that hot its time to get a new cat or delete it.

 

You need one of these:

 

 

That's what i got!

[SVPete]

There is supposed to be a fiberglass heat shield on the passenger floor in that area. Perhaps it was thrown away after a water intrusion problem?

[onlyinajeep726]

Being in NC, you're required to have a cat, but with that said, it's merely a visual check that it's there at inspection time.  No sniff test or other verification of it working.  Sooooo, instead of cutting it out and patching that section with a piece of pipe, unbolt it from the downpipe and break up the comb, and blow it all out.  Sounds like you have a blockage forming anyway because there should not be enough heat collecting in there to melt stuff under normal operating conditions.  If you're still unsure how you want to resolve it, make a two hour drive to my home town, below Raleigh, and I'll do the work for you for the cost of the pipe and lunch.  Seriously.  I'd rather your MJ not burn to the ground.

[Rymanrph]

Since I have the 97 conversion, if I delete the cat, won't it throw a code?  I know it's petty, but I really don't want a CEL on the dash all the time.  I don't have the option of unbolting it unfortunately - mine is completely welded in.

 

I guess it's possible that my O2 sensors are not doing their job and causing the wrong fuel mixture.  It wouldn't surprise me that anything is bad after over 200k miles.  It might be worth it to replace those and the cat at the same time.

[DirtyComanche]

Since I have the 97 conversion, if I delete the cat, won't it throw a code?  I know it's petty, but I really don't want a CEL on the dash all the time.  I don't have the option of unbolting it unfortunately - mine is completely welded in.

 

I guess it's possible that my O2 sensors are not doing their job and causing the wrong fuel mixture.  It wouldn't surprise me that anything is bad after over 200k miles.  It might be worth it to replace those and the cat at the same time.

 

If you're running the whole 97+ EFI, yeah, it needs a cat and a rear O2.  Or at least I assume it does because that's how I recall it being set up.  However, you can delete the cat and buy a cheap simulator rear O2 sensor and it will (probably) not throw a code.  The rear O2 does not impact engine operation, it is just to monitor emissions.

 

If there is something wrong causing a lean/rich condition right now, it should probably still throw a code...  However, if everything is original, yeah, replacing the O2 sensors and the cat would not be a bad idea.  Along with doing all the other normal tune up items.

[onlyinajeep726]

IDK about the '97 and onward, but on my buddy's '96 XJ, removing the cat and associated O² sensor didn't make a bit of difference in how it ran, nor did it throw a CEL.  Granted, it has 285k miles on it so it may or may not be running optimally anyway haha.

[shelbyluvv]

I have a 97+ truck. It will throw a code. I also have a 96 XJ with a hallowed cat. It throws a Catalyst Efficiency code all the time. As a matter of fact, the CEL is on right now for the cat. Your buddy's CEL is burnt out.

[Rockfrog]

Core the cat, and install an 02 sensor elbow in the rear O2 sensor bung (then re-install the O2 sensor). This will create enough differential in reading that even OBD II won't throw a code. The rear simply monitors the variation in reading between the first O2 sensor and the second O2 sensor.

 

I also own a 2000 XJ, wanna guess how I know this works?

 

Sent from my SM-G930W8 using Tapatalk

[HOrnbrod]

True, it should, but it probably won't pass the visual inspection in NC. Even the lamest state inspection drone should be able to see that the elbow doesn't belong.

[Rymanrph]

I'm looking at this cat right now:

 

https://www.summitracing.com/parts/mpe-94006

 

It doesn't have an O2 sensor bung, but I figure the exhaust shop can add one when they weld it in.  That's what was done to my current cat when I did the '97 conversion.  I also found both O2 sensors for about $65 shipped which seems pretty decent.

[HOrnbrod]

I used that same Magnaflow cat for a couple of years when my clogged original went down. It's a high quality unit with very little exhaust restriction. Well worth the $$ IMO. 

[onlyinajeep726]

I have a 97+ truck. It will throw a code. I also have a 96 XJ with a hallowed cat. It throws a Catalyst Efficiency code all the time. As a matter of fact, the CEL is on right now for the cat. Your buddy's CEL is burnt out.

 

Light works fine.  Not saying you're wrong about it throwing on the light, but it evidently didn't phase the Jeep's PCM with it unplugged.  Just my observation on that particular Jeep.

[shelbyluvv]

96 XJ with a hallowed cat. The CEL comes on every few days.