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New y-pipe problems

Discussion in 'GM Powertrain' started by KyleZ71, Mar 10, 2013.

  1. KyleZ71

    KyleZ71 New Member

    Hope everyone isn't pissed at the world for the hour forward last night, but happy Sunday regardless. I recently had a Flowmaster y-pipe with dual cats to replace the factory set up as the check engine light was on for bad cats. So far I noticed much better flow, but also a strange metallic sound. When driving only, it sound like someone is shaking a can of spray paint. It is very noticeable when I don't have the radio on. After checking for clearance issue, I could not spot anything. This only started after the installation of the y-pipe (local muffler shop installed it). This morning I took I to one of their sister stores and the mechanic said he could not find anything that could be causing the sound. He check the clearance and even tapped everything with a hammer and still nothing. I'll be calling Flowmaster on Monday to report the issue. Kinda ranting here but does anyone have an idea what could possibly be creating the sound?

    - - - Updated - - -

    I'll give them a call in the a.m. tomorrow. Didn't know if anyone had a similar run in or an idea.
  2. KyleZ71

    KyleZ71 New Member

    After installing the second y-pipe with cats from flowmaster I still have the same rattle. I put an engine stethoscope to the cats and flanges while idling and can not hear anything. I can only hear the rattle while moving. The clearance is good and I double checked the bolts, but can not pin point the rattle. Anyone have any ideas?
  3. RayVoy

    RayVoy Active Member 1000 Posts

    Could it be a muffler with something trapped inside, or with a loose baffle?
  4. KyleZ71

    KyleZ71 New Member

    The sound seems to be right under the floor boards. And also I did not have this problem until immanently after the ypipe swap
  5. RayVoy

    RayVoy Active Member 1000 Posts

    Mis-understood, thought you have changed the whole exhaust as well.

    Ok, maybe the installer forced the old pipes and muffler out of alignment, did you check the complete exhaust for clearance?
  6. KyleZ71

    KyleZ71 New Member

    I'll have to recheck after class tomorrow. If that isn't the problem I had thought maybe the shields on the cats are poor quality and thats whats rattling
  7. RayVoy

    RayVoy Active Member 1000 Posts

    Try jamming a piece of wood into the space between the cat and the shield. don't force it, just enough to stop any vibration.
  8. KyleZ71

    KyleZ71 New Member

    Good idea. I'll have to give that a try
  9. KyleZ71

    KyleZ71 New Member

    Took it to the garage yesterday and they did what no other garage would do. They lifted it, and then put it in gear so they could hear the rattle, as it only rattles when moving. The good news is we've pin pointed the problem, bad news is they believe its the transfer case.

    During the winter months, I had a severe allergic reaction and went to the pharmacy in 4wd. Since I need to get benadryl, now I did not hold back on the gas. I heard a loud pop during that time, but I guess it took until installing the y-pipe until the rattling started

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