Hey everyone,

I have a 98' XL with 95K on it. Recently, the cats started rattling and the problem is the heat shields. Think it would be cool to remove them without replacing with new ones? Or would it cause problems?

 

miss post - my fault

 

It would definately cause problems. You truck is probably 80% electric and 20% engine. It would create smog issues on top of rough idle problems, lean conditioning, and the truck would probably run worse. If I were you I'd just buy some magnaflow high flow cats for $40 off ebay. That will be just as good as running straight pipes. Getting straight pipes for the cats only MIGHT get you 1 or 2 RWHP. Putting high flows on will do that gauranteed.

 

The problem is a small tag between the cat and the heat shield I am told if you get a pair of needle nose you can grab that tag and rip it out, problem sovled, no real work or money involved. And that sound is rather annoying isnt it? I would have fixed mine but I have a tedency to be a bit lazy....

 

I don't know why people keep suggesting it's the heat shields or some mysterious tab that fits between them. I had this exact same problem a week ago and inquired here about removing the cat. The usual above responses were given, get hi-flos, pull out the tabs, etc.

First off, I don't know what kind of truck y'all are running but on mine there are no tabs between the heat shields and the cat. What purpose would that serve? The only thing I could think that would do is transfer heat from the cat into the shield, which defeats the purpose of having a shield there in the first place. I could run my hand between the shield and the cat and it was all clear space.

And furthermore it usually ISN'T the heat shield, it is the cat itself. In my case it was the primary driver's side (there are four cats on this engine), the one bent in an elbow shape. How do I know this? Because I drilled stainless screws into it in an attempt to shut it up, WHICH WORKED for a few kilometers until it rattled loose again. Basically the Pt/Rh catalyst inside deteriorates and eventually becomes loose inside, causing the noise. Replacing it meant replacing the entire exhaust pipe and BOTH cats for some $700-odd CAD. I took it to a muffler shop and had them cut the offending cat off and weld on a piece of straight pipe, and lo and behold I actually gained some torque out of my old beast!

I had them give me the old cat and on the intake side, I could see it was plugged up immensely with all manner of brown crap. I couldn't imagine how exhaust gases actually got through it. Best part was it only cost me $75 CAD. I'm thinking I'll get the other one chopped too!

This doesn't apply if you live in an emissions-controlled area, of course.

 

Yep, I have the same problem, and have had it for months.Same side too. I removed my heat shields, no tab, put 'em back, still rattled. I have another thread here titled "exhaust part help", abouth the same thing.I don't want to remove the cat, because even though now we don't have emissions testing, it will be here soon I'm afraid.

 

Jimmy dean is right about the tab....I have had that prob myself. its a piece of stamped sheet metal about the size of a credit card and tac welded on the four corners. there is a slit in the heat sheild on the bottom, near the front. Look in that slit with a light youll see it. I got a cat rattle myself inside the cat....i found the best cure is to find a way to drive so you dont hear it...or crank the radio. Replacing them is out of my budget right now

 

Yeah, the honeycomb holes in cats are so small that they will eventually clog up with carbon and need to be removed or replaced, or cleaned. I wonder if you can take them off and spray disk brake cleaner through them, or carb cleaner through them. Do you think this is possible??

 

Found it!! The problem is the converter on the driver's side. I was able to remove mine from the manifold to the first slipjoint, and when I got it out and turned it upside down, all sort's of crap came out.There were chunks of converter "brick" along with a load of smaller pieces. Guess what?? No more rattle, go figure.