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Rattling Muffler Heat Shield

Discussion in 'Gen II Prius Technical Discussion' started by TonyPSchaefer, Mar 30, 2009.

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  1. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator Staff Member

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    The heat shield covering the muffler has started rattling. I climbed under the rear and did a little light bending. That toned it down a little but it's still there from time to time. At certain revs, there's the rattle.

    Is the rubber bumper supposed to rest on the muffler or is the shield supposed to 'float'?
  2. jayman

    jayman Senior Member

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    Could be the heat shield is starting to actually rust out. I've had that happen to other vehicles after 4-5 years

    Want me to post a schematic later?

    Speaking of schematics, Mr BACNet, how is that tail light behaving? Flicker flicker ....

    Awww I'm just kidding, here, have a hug

    :hug:
  3. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator Staff Member

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    Ah shucks. Now I'm all warm and fuzzy inside. But could be the alcohol.

    The shield is not rusting out from what I could tell. What I could see was still nice and bright and shiny. Once it's warmer outside I'll spend a little more time under the car.

    Considering that I couldn't tell the taillights were out in the first place, as far as I know they're just fine! :D
  4. jayman

    jayman Senior Member

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    Yeah the booze works for me too

    Can you actually move around the heat shield? Does it feel tight, eg securely fastened

    With my FJ, to grease the zerks on the front driveshaft, its easiest to remove two 12 mm bolts and take off a teeny skidplate that is bolted to the crossmember.

    I once forgot to properly tighten the two bolts, and under more than moderate acceleration heard a weird buzzing noise under the FJ. I though "what the F Bomb is wrong with this thing?"

    Back at the house, had some time to kill the next day and crawled around under the FJ. Sure enough, the teeny skidplate was loose.
  5. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator Staff Member

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    I thought it was the license plate for a long time. And since it was only when I was moving it was difficult to confirm. Then one day was rattling at an idle.

    My brief examination seemed to give the impression that it's attached only on the wheel side and not on the tank side. That's why I asked about it floating. I thought that perhaps it's supposed to be attached on one side and not touch anything on the other.

    If you have the schematics that would be great.
  6. jayman

    jayman Senior Member

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    Well, [Sarcasm Mode = ON] the shop manual is unusually vague on the location or existence of this shield [Sarcasm Mode = OFF]

    Here is the exhaust system outline

    [​IMG]

    It would help if you could get the car up in the air, eg safely jacked up and supported. On my FJ, the shields in the rear are actually a fiber material, NOT metal. There have been a couple reports of this fiber shield actually being damaged, falling directly onto the tailpipe, and CATCHING FIRE

    So I ripped the fiber shields off my FJ. I suppose if I was really worried about heat from my FJ exhaust, I'd either get it ceramic coated, or just use header wrap
  7. jayman

    jayman Senior Member

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    Well, f*** a duck

    I went for groceries today in the FJ (I sold my Prius Wed to a taxi operator, considering getting a 2009 or waiting for a 2010 Prius) and noticed an odd buzzing vibration coming from under the passenger seat, but *only* under moderate acceleration

    Back at the house, in the comfort of my heated attached garage, put on some coveralls and went looking underneath the FJ passenger seat. The passenger side catalytic converter has a metal heatshield above it, maybe 3 ft long from the firewall to about under the passenger door area

    Near the firewall is a bolt that secures the metal heatshield. It looks like the heatshield has some sort of fatigue crack, which runs through the bolt hole to about 15 mm each side.

    So the heat shield is not only *very* loose on that side, it has actually pulled through. Sonovabitch!

    :mad:

    Went to the dealership, it appears a handful of Tacoma's and FJ's have done that for unknown reasons. Have to wait about 2 weeks for a new heatshield, yes it's warranty

    Light turns green, step on gas, BUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
    ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ

    I hope you're happy, Tony. My FJ caught cooties off your Prius
  8. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator Staff Member

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    Any chance Priapus can catch your FJ's warranty cooties?

    And it's no surprise you caught something what with the water fowl activities and all.
  9. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Hi Jay,

    Tell us more. How many miles on your car?

    Now you'll have to change your profile to read "Other non-hybrid" until you purchase another Prius! :rolleyes:
  10. jayman

    jayman Senior Member

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    I'll ask, it can't hurt. Right now I feel like ripping the damn shield right off, but knowing my luck the FJ will burst into flames



    Oh boy .... probably just reading about your misadventures doomed my FJ. What next? Will my tail lights go flicker flicker?
  11. jayman

    jayman Senior Member

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    192,000 km, according to the paperwork. Routine maintenance, though I was getting ready to replace the struts. My Prius has a new life as a taxi cab

    That tells you something when a taxi operator would rather buy a used - but well treated - Prius over a Crown Vic



    You're a mean and heartless fellow ...
  12. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator Staff Member

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    I have a resolution!!

    It was driving me crazy. When I idled first thing in the morning, the thing would rattle. The car/muffler would go through resonance in which it would rattle softly, then get louder, then die down. Then repeat. As I idled through the parking lot at work (to heat the CC prior to hopping on the 45mph road) it would rattle quite embarrassingly.

    So this evening I finally crawled under and did more than just look around. Again, I noticed how little space there was between the muffler and heat shield. Figuring that the whole thing came about after I - er, I mean someone - backed over a landscaping rock (IMG 1), I tried pulling on the muffler to lower it a little.

    ** NOTE: I don't recommend this for the weak of heart. **

    As I pulled and increased the effort, the muffler quickly dropped about 4 - 5 inches and there was a squeak. My heart sputtered as imagined pulling out a rusted bolt or something. Instead, I noticed that the rubber gasket was turned (IMG 2). Nothing broken, just that.

    So I took pictures. I want confirmation that this is the way it's supposed to be. Then I twisted the gasket back up the way it was to show that (IMG 3). Note the plastic melted by the higher position of the muffler. Also, I took a picture of where the heat shield was rattling (IMG 4).

    Attached Files:

  13. jayman

    jayman Senior Member

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    I'll let you borrow my FJ next time you feel the need to go offroad

    Looks like the heatshield is all bent to hell too. I realize you don't have access to a proper lift, and/or a safe means of supporting the vehicle, but you're going to have to bend that heat shield into position

    Notice the little rubber tit on the heat shield - image 0095 - appears a good 1/2 inch away from the body. There is a similar heat shield used on one of the catalytic converters on my FJ Cruiser, and the rubber tit actually touches the body

    You may want to inspect forward of the muffler. It's entirely possible a mounting bracket has been pulled out of the rubber grommet, allowing the muffler/pipe to move a lot, droop, etc
  14. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator Staff Member

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    A while back, uncertain what was rattling, I bent the heat shield on the premise that the rubber thingy was vibrating against the muffler and/or undercarriage. So that one was my fault.
  15. jayman

    jayman Senior Member

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    Hmmmm I dunno. First the tail light is going flicker-flicker blinky-blinky, now this. Are you sure you're not a malfunction magnet?
  16. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator Staff Member

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    Well, the taillight blinky blinky happened on its own, I might have had something to do with the dents in the muffler.

    About the rubber forward of the muffler, what is it supposed to look like? That's my problem. I might have noticed that the rear rubber was wrong if I'd known what 'right' looks like.
  17. jayman

    jayman Senior Member

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    That rubber thing is just to hang the exhaust system from. If you bend the rubber thing up, it may temporarily hold the muffler, but it will slip back down.

    I suspect further up under the car, one of the hangers became dislodged from the rubber thing when you ... ahem ... went offroad. If you can pull down on the muffler and the entire thing drops 3-4 inches, a hanger is missing and/or off the rubber thing

    I noticed in the photos, a fair bit of corrosion on the muffler hangers. Gotta love all the salt they dump on the roads in winter! It's entirely possible when you pulled the Mad Max stunt, a weakened hanger broke off. I've had that happen to older vehicles by NOT driving off road, just got to the point the rust-eaten hanger finally let go, and suddenly the muffler is dragging on the ground

    Carefully support the car, as safety is rule number 1. Now carefully inspect the entire exhaust system, from the catalytic converter rearwards. If you see any of those rubber things without any obvious exhaust pipe hanger in it, that could be the answer right there

    Unfortunately, that means you may have to invest in a new exhaust system. When I was young and a lot poorer than I am right now, I tried all sort of bandaids to keep things together. Those bandaids are, at best, very temporary fixes
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