Can anyone help me identify this rattling noise? It seems to be coming from under the Blazer.

Well I had a video, not sure how to post it.

 

Please provide mileage on unit. But it seems to be the usual bad cat symptom.Mostly at low revs or under load,right? The rest of the exhaust system may need work as well.If the rattle is road related(bumps etc) then you have a bushing issue:shocks,sway bars,control arms...Do a search on this site for your answers! Good luck!

 

The stock cat has a monolithic element that will rattle because the matrix has broken from the shell . When the engine has not been run for a few hours , the converter (now cool to the touch) can be shaken by hand to verify failure .

 

if that checks out ok then I would look at the flex plate and converter bolts make sure the plate isn't cracked and the bolts are tight

 

Thanks for the help. Yes it's only at low rpm or when I get on it right at first. It has just under 96k on it.

I'm going to check the cat today.

I will go ahead and check the flex plate and converter bolts while I'm at it anyway.

I'm pretty sure there are some bad bushings as well because it also makes jingling noises over bumps. I guess it's time to keep up with everything.

 

It's definitely the catalytic converter so I'm wondering if I should spend the money and get the whole flange x flange piece or just the cut n fit universal or just run it straight. Any suggestions? I'd have to go to a shop to have the universal welded on.

 

well I would go with the new flange if the shop thinks the rest of it will hold longer then you think your going to keep the truck

If not new cat if ya run straight pipe the check engine light will stay on so new cat i would go with