What's that tinkly noise?

Discussion in 'Engine' started by amwebby, Jul 28, 2008.

  1. amwebby

    amwebby Hardcore MB Enthusiast

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    Just lately when accelerating I have noticed a strange tinkly metallic noise coming from the rear of the car. This only happens very rarely and it seems to be in a very limited rev range, which makes me think some part of the exhaust is vibrating at certain revs. It may be the I am only noticing it because the current hot spell has seen me wind all the windows down.

    Anybody got any idea what this might be? Should I be worried?
     
  2. BTB 500

    BTB 500 MB Club Veteran

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    Could just be a rattling heat shield. But it might be one of the cats ...
     
  3. OP
    OP
    amwebby

    amwebby Hardcore MB Enthusiast

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    No, I checked, the cats are all in the garden, sleeping in shady spots it's so hot.

    Seriously, if it is one of the catalytic converters, what does that signify?

    I did a visual check, no apparent loose heat shields although it is hard to tell without putting her up on a ramp.
     
  4. SilverSaloon

    SilverSaloon MB Club Veteran

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    probaby a big dent in your wallet :mad:
     
  5. BTB 500

    BTB 500 MB Club Veteran

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    It means the catalyst matrix is breaking up and you can hear bits rattling around at certain revs.
     
  6. OP
    OP
    amwebby

    amwebby Hardcore MB Enthusiast

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    Any other signs that would help me determine if this is the problem?
     
  7. Smiley

    Smiley Hardcore MB Enthusiast

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    could be down on power, increased fuel consumption and emissions - best bet if you have a friendly mot tester is to have an emissions test done; at least that will tell you if the cats are working fine.
     
  8. Smiley

    Smiley Hardcore MB Enthusiast

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    ps - mind you with the CL500's power it would have to be pretty bad before you noticed that - more like increase in fuel would be first symptom - depends how closely you watch it.

    Or best case it is a rattly heat shield.
     
  9. OP
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    amwebby

    amwebby Hardcore MB Enthusiast

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    Thanks. Power and fuel consumption haven't changed. It's due an MOT on the 6th of August. Guess I'll find out then.
     
  10. tromppost

    tromppost Hardcore MB Enthusiast

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    I do not think it will show on the MOT, If it is one of the cats they are more to the center of then car than the rear, with the door open rev the engine slightly, you should hear a rattle that you can control with your foot. if that make sense. It's best to get it replaced sooner than later because they brake up and may blow back in. This may be mad info as I am no machanic. (or speller)
     
  11. OP
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    amwebby

    amwebby Hardcore MB Enthusiast

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    I've been watching fuel consumption very closely with the current high priices, who isn't, especially those of us for whom 24 mpg is a really high figure. Nothing seems to have changed and the figures match the recorded ones given in the manual.

    I think I will get the MOT done by my local friendly independent and ask him to check cats and heat shields then.

    P.S - didn't I read about some exchange scheme run by MB for cats?
     
  12. kbhogalW126

    kbhogalW126 Hardcore MB Enthusiast

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    Further to this thread I checked the WIS and it mentioned that the handbrake shoes? may need adjusting.

    Hope this helps.

    Regards,

    KJ
     
  13. OP
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    amwebby

    amwebby Hardcore MB Enthusiast

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    Got back from Basel last night, picked up the car from the airport parking, and noticed the tinkly noise is now more of a rattle. It only seems to be at about 15-25 mph and disappears when the engine is warm, making me think it's a loose heat shield or exhaust connection.

    I've done a visual inspection by setting the suspension setting to the highest setting and looking underneath on the drivers side (where the noise appears to be coming from) but can't see anything.

    The car is booked in for an MOT on Monday. Is this something that might cause a fail?
     
  14. BlackC55

    BlackC55 Authorised Forum Sponsor Authorised Forum Sponsor

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    Sounds like a CAT to me.....

    I doubt it will cause a MOT fail
     
  15. Smiley

    Smiley Hardcore MB Enthusiast

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    If the cat has gone then it may fail the MOT on emissions. If it were mine I would ask the MOT guy to check the emissions first before he starts the formal MOT test - once he has started it on the electronic database he has to finish - and if it then fails there is a grey area if your current MOT is still valid or not - until it expires. So if you get him to check the emissions first see if there is a problem you can get it fixed before the current MOT expires a bit more at your leisure - assuming you are not close to the expiry date.
     
  16. Dieselman

    Dieselman Banned

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    What do you mean by this.?
     
  17. OP
    OP
    amwebby

    amwebby Hardcore MB Enthusiast

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    Coming as it does from an informed source I'm worried you may be right. What is the cost of a new CAT?

    Edit: Just looked it up on EPC Net and Inchcape, £648 a side. Anyone know of anything better/cheaper?

    I've read about "sports cats" what are these?
     
    Last edited: Aug 1, 2008
  18. Smiley

    Smiley Hardcore MB Enthusiast

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    I always take my cars for the mot well before the expiry of the old one just in case they need some work - my local mot test station told me that with the new electonic mot system as soon as the car fails it shows up on the records as having failed - so you may be pulled over by the police - even though there may be a month left on the old MOT.
    The only way around it is to have a pre MOT without starting the electronic DVLA record - of course this means more effort for the tester.
    Seems a bit unfair to me - but I can see what they are saying.
    Maybe someone else can clarify for sure.
     
  19. BlackC55

    BlackC55 Authorised Forum Sponsor Authorised Forum Sponsor

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    With your car ONLY fit genuine CATS as after market types sound awful and are a pig to fit.

    They are expensive but worth it:p :)
     
  20. sweeney

    sweeney Hardcore MB Enthusiast

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    what's that tinkly noise??

    must be Barry's final thread ! :eek:
     
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