Hey guys I have been getting a rattling noise from underneath the truck for a little while now. So today I left it in idel, and I crawled up under the truck to have a listen. I found that the rattle is coming from around the driver's side cat (when I held the cat still it wouldnt rattle anymore). I shook the system and it doesnt seem to be that loose but I dowant the noise to go away. How do i go about tightening it up. Thanks alot

 

You have to replace the cats, but before you do, you need to find out what killed them, bad fuel, wires, plugs, stuck injector or coolant leak or it will just happen again.
Do you have any check engine lights on, if so what are the codes? When was it last tuned with new plug wires, what octane gas are you running?

 

give the cat a bang with a rubber mallet, if it rattles, it is bad. Do what Mike suggested and figure out what killed it.

When you go to replace it, look at the Magnaflow high flow cats. I got both of mine replaced for $325. Midas quoted me $450 for just one. Go to their website and find a dealer. depending on your area, you should be able to get them done somewhere around that price...

 

Ohh I think i might have mislead you guys. What I meant in the original post is that the entire exhaust system rattles on something. If I just simply put my hand on one of the pipes along the driver's side to prevent it from shaking, the rattle will go away. The sound is coming from the exhaust hitting into something else rather from inside the pipes themselves. I went out and hit both cats and they dont rattle themselves at all. I think I might need a new bracket or something. Any help.

Sorry for the confusion, and thanks for the help

 

I had a similar sound coming from my exhaust, my first thought was also the cats. I checked the cats, then followed the system to locate the rattle. On mine it turned out not to be the exhaust system itself but the heat shield mounted above the mufflerwas the culprit. There are to studs which the shield mounts to and one of the nuts had worked itself off leting the shield come into contact with the muffler periodically. Simple fix. If this is not the problem on yours then you need to carefully inspect the system from front to back to locate your rattle area, certainly is possible you have a rusted hanger which came loose.

 

Make sure all your mounting points are still in tact. I dont know how one could come loose but if the entire system is shaking that could be one problem.