cadillacbob Posted April 11, 2007 Report Share Posted April 11, 2007 Hey fellow sser's! I have a new noise... A rattling noise sounding somewhat 'metalic' or similar to a diesel coming from under my truck... I can hear it when the truck is warm or cold...It sounds the same... I can hear it mostly in park or cruising slow as the noise bounces off of the curbs... It is somewhat quieter as I raise the rpm's on the engine...but it is still there... It sounds like it is coming from everywhere!!! Any clues or tricks to narrow it down to the source? It almost sounds like it is coming from the cats, but i dunno... Like I said, it is very noticeable, and sounds like it is coming from everywhere... Any advice would be appreciated! Thanks in advance! boB Quote Link to comment Share on other sites More sharing options...
Krambo Posted April 11, 2007 Report Share Posted April 11, 2007 Could be anything but most likely the substrate separated in your cat. You will want to address that as soon as possible to prevent engine damage. Quote Link to comment Share on other sites More sharing options...
cadillacbob Posted April 11, 2007 Author Report Share Posted April 11, 2007 If it is a cat...Would it be worth the effort of just punching them both out??/ would I gain or lose anything? Need a pcm retune? Is it a big p.i.a.??? Quote Link to comment Share on other sites More sharing options...
H8R Posted April 11, 2007 Report Share Posted April 11, 2007 Some exhaust leaks can be tricky, and hard to pinpoint, but it could be a slight leak.. usually you would hear it more when sound bounces off of somthing. Quote Link to comment Share on other sites More sharing options...
superredss Posted April 11, 2007 Report Share Posted April 11, 2007 if you remove the cats you'll definitely have to trick the computer into knowing that they are not there. I had a major problem with that on another car, I ended up putting them back in. I am not sure if cats on the trucks have heat shields or not but that might be also something to check. Quote Link to comment Share on other sites More sharing options...
Bad Bowtie Posted April 11, 2007 Report Share Posted April 11, 2007 Both mine & my father's 2004 GMC VHO's have had a vibrating metallic sound from the exhaust heat shield under the passenger floor. We just kept jacking with that heat absorbing material bending it and such until it simply was adjusted enough and went away.... Check yours out & Good luck! ;) Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted April 12, 2007 Report Share Posted April 12, 2007 its either a bad cat or a loose heat shield........if its the cat, the rattle will get worse in time and will be more prevalent at higher RPM's....... Quote Link to comment Share on other sites More sharing options...
ridndirty Posted April 12, 2007 Report Share Posted April 12, 2007 this just recently happend to me when i got my headers put on. they are in a slightly different angle. i also cut off my tips right after the muffler so 2 of my hangers were gone. this made it rattle against the frame. i just got some plumbers tape (metal stripping) and secured it against a cross member just as a temporary fix since im redoing my exhaust setup anyway. Quote Link to comment Share on other sites More sharing options...
detjoe Posted April 12, 2007 Report Share Posted April 12, 2007 I broke my dip stick during my trnas work and that makes a noise some time, see if the welds broke on the part that bolts it to the head. -we need to get to gether with Detroit SS's this summer! Quote Link to comment Share on other sites More sharing options...
cadillacbob Posted April 12, 2007 Author Report Share Posted April 12, 2007 all great ideas! Thanks... I will post when and how I fixed it! Yep Detroit SSer's...I never had a chance to go to the track last year... or meet any fellow ss owners at any rally's...I will definitely hook up this year... If you are wondering, I refinanced my truck, and the payment went down $250...So I might as well keep her awhile... boB Quote Link to comment Share on other sites More sharing options...
cadillacbob Posted April 16, 2007 Author Report Share Posted April 16, 2007 Went to the dealer this morning.... I have had great luck with them in the past... I need cats... Special order...part should be arriving in 1 or 2 days... They told me to keep drivin'... andn they had to repair the rear o2 sensor wires... Thanks for the replies again... The dealer told me it is not very common for it to happen... But I did have the stock pcm back in...glad I saved the stock pcm... Quote Link to comment Share on other sites More sharing options...
cadillacbob Posted April 23, 2007 Author Report Share Posted April 23, 2007 I have been driving with the new cats for a few days... My truck runs 100% better now...I think they where slowly dying... My MPG has increased +2... And it runs , idles, everything smoother...better than new...Too bad there is not a way to tesr for cats that are dying...next time I will gut the bastards if they fail... Quote Link to comment Share on other sites More sharing options...
pimp ss Posted April 24, 2007 Report Share Posted April 24, 2007 noticed a rattle under mine and checked it and the y pipe and the rear pipe where they come together are loose and rattle like hell when i bang on them im goin to see my buddie at the muffler shop in the morning Quote Link to comment Share on other sites More sharing options...
cadillacbob Posted April 25, 2007 Author Report Share Posted April 25, 2007 One more thing... I thought I had a problem with the rear o2 sensors...I had two codes and the light was on... The Tech did not replace the o2 sensors, he repaired the wiring,,,hmmmmm Seems like he replaced a fuse or two based on what I read on the repair order...just fyi Quote Link to comment Share on other sites More sharing options...
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