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URGENT HELP NEEDED: Muffler burning undercarriage!!!

D

dmilam

NAXJA Forum User
Location
Colorado
I searched the forums and found nothing related...

Vehicle and equipment in question: 1996 XJ, Flowmaster Series 40 muffler and a Hi-Flo CAT.

Description of problem: Under the back seat, on the passenger side, right above where the muffler is, the undercarriage is getting extremely hot when driving in the mountains, to the point where smoke is emitting from under the seat. When I pull over and check the problem, I lift up the seat bottom and find that the undercarriage metal is actually burning the carpet and padding. I had my speaker wires running to my amp through this area and the wires are completely cooked. The smell is terrible. This only happens when the engine is working hard for long periods of time, like when 'wheeling or going up long mountain passes. I've had this exact setup on previous XJ's with nothing like this ever happening.

Any suggestions would be very helpful.

Thanks,
Dan
 
I have this same problem and I would love to know what the heck causes this. I have the exact same set up, Flowmaster 40 series and a high flow cat. I think there has to be something wrong, I took my carpet out once and had a friend in the back of my Jeep. Driving really hard in the sand it actually melted his shoes to the floor!!
 
This is a common issue, especially if you get a hole in the cat or muffler. You need to fashion a heat shield to go between the muffler/cat and the body. Some years actually had one built onto the muffler/cat. I found that an air bake cookie sheet works well for blocking the heat.
 
WhoA i have the same problem i put on the series 40 but catback and a half dollar hole appeared right before the catalytic converter somethins up, and i try to wrap it with the best heat resistant bandages but i break all their claims especially the "blow torch" tested ones

am i gonna have to get a whole new headers back or what you guys think cause sittin in traffic the monoxide is excellent until you have to drive again... all dizzy
 
old_man said:
This is a common issue, especially if you get a hole in the cat or muffler. You need to fashion a heat shield to go between the muffler/cat and the body. Some years actually had one built onto the muffler/cat. I found that an air bake cookie sheet works well for blocking the heat.
Click to expand...
Would a cookie sheet work better then a sheet of aluminum?
 
The "air bake" cookie sheet that old_man is referring to is a very specific brand, and style of cookie sheet. Yes, it's made out of aluminum, but there's an insulating air gap between the top and bottom.
 
A good heat shield is probaly the answer for most of ya but remeber that a cat it desined to burn the fuel that the eng don't!!!!!!

I thing i would start with a tune-up and a compression check!

If the eng don't burn it..... the cat will! Then the heat is way to hot for the muffler so now you need a heat shield there too.

:dunno: Maybe the new HP cat........just work to good.!?:wow: ;)

Flash.
 
ChiXJeff said:
The "air bake" cookie sheet that old_man is referring to is a very specific brand, and style of cookie sheet. Yes, it's made out of aluminum, but there's an insulating air gap between the top and bottom.
Click to expand...
So, is it better?
 
How are you fixing your airbake under the rig, .. to the floor, or to the cat/muffler?
 
Either will get the job done. I took a couple of pieces of .060 aluminum 4"x1.5". I pop riveted them on oposite ends of the cookie sheet, then bent them down 90 degrees and then put another bend to make a tab parallel to the exhaust pipe. I then uses a couple of ordinary muffler clamps to clamp them to the pipe. The sheet ended up roughly half way between the cat and the floor.
 
I might just have to try this. ;) My cat burned a hole through the heat shielding the local exhaust shop sold me. :)
 
If you have a Sam's Club in town, they have the Air Bake as cheap as I've seen.
 
This is common, and it's happened to me a number of times. The muffler can get pushed up from hitting stuff underneath when wheeling, the floor can get partially rusted out, or whatever. The heat causes the insulation that's under the carpet to smolder........I've had to douse mine with a water bottle a couple of times. The quickest and easiest fix is to put a couple of layers of aluminum foil under the carpet insulation. Adding a heat shield between the muffler and floor is a more elegant solution, but I can tell you from experience that the aluminum foil gets the job done. :)
 
I did the cookie sheet fix. The one on the cat can be bolted with U-bolts or muffler clamps to the pipe, but for the muffler I had to bolt it to the floor. I dont have carpet, so I will also be wrapping the pipe when I get around to it.
 
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