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disconcerting 308 noise at idle when warm

Discussion in 'Technical Q&A' started by corse driver, Aug 21, 2004.

  1. corse driver

    corse driver Rookie

    Aug 19, 2004
    15
    My 82 308 is making an odd noise at idle when it is fully warmed up. It is coming from the right side of the motor and sounds like a noise caused by a rotating assembly or belt. The noise quickly dissapears once the engine is away from idle and it only occurs when the car is fully warm. I looked at the right side with the wheel and wheel well off while running (however the car had cooled down at this point) and listened to things with a long screwdriver to my ear and everything sounded normal. Got any ideas?
     
  2. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,167
    San Carlos, CA
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    Mitchell Le
    Right side, passenger side, probably timing gear bearings (any one of four). Try a stethoscope.
     
  3. tbakowsky

    tbakowsky F1 World Champ
    Professional Ferrari Technician Consultant

    Sep 18, 2002
    15,098
    The Cold North
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    Tom
    Best way to determine if the nosie is an accessory or engine,is to remove each belt one at a time and fire up the engine to see if the noise disappears. Obviously when you get the water pump/alt belt off run the car for only a short period. The A/c belt is going to be a pain in the butt to remove,but hopfully by just removing the waterpump belt you will discover your noise. By what is being described,it seems to me like a waterpump bearing has gone south. Lets just hope it anit the cam drive bearings like the others have said..cause those are a bummer to replace.

    Goodluck!!
     
  4. f355spider

    f355spider F1 World Champ
    Rossa Subscribed Owner

    May 29, 2001
    17,058
    USA
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    Hugh G. Rection
    Try pushing your clutch pedal in and out and check for the noise......
     
  5. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,992
    Groton, MA
    Full Name:
    Verell Boaen
    There are only a few sources of bearing like noises on the passenger's side of the engine. They are:

    - Alternator bearings
    - A/C compressor
    - A/C belt tensioner
    - Water Pump
    - Cam belt idler pulleys
    - Cam Belt drive bearings

    Temporary belt removal is the quickest way to determine if it's one of the 1st 4. Just don't run more than a couple of minuites with the water pump belt removed for obviouos reasons. A mechanic's stethescope is the best way to diagnose further w/o disassembly.

    Water pump bearing failure is almost always indicated by a brownish stain and/or cooland trailing down from the weep holes in the bottom of the water pump's nose. Often this is a leading indicator of emminent WP failure.

    I have seen the weep holes clogged up with RTV after a rebuild, thus preventing weeping, so it's a good idea to clean them out with a q-tip or a drill bit. If they're clogged with grease, it's usually being cooked out of a bearing.
     
  6. corse driver

    corse driver Rookie

    Aug 19, 2004
    15
    I am going to use a mechanics stethescope on it tommarow and let you all know what I find. I am hoping it is not related to cam belts or is the water pump. The alternator is much easier to replace I think and I don't care about the AC anyway.
     
  7. robertgarven

    robertgarven F1 Veteran
    Rossa Subscribed Owner

    Feb 24, 2002
    5,082
    Ventura, California
    Full Name:
    Robert Garven
    When my timing gear bearing went I heard a slight rattle at idle, with the wheel off i could see the timing gear pulley moving around, not a good thing. I also had a transfer gear rattle once rasied the idle to the proper 1000 rpms and it went away, the car is not made to idle below about 800 and the surging made the transfer gears rattle.
     
  8. Verell

    Verell F1 Veteran
    Consultant Owner

    May 5, 2001
    6,992
    Groton, MA
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    Verell Boaen
    Actually, the water pump is the easiest to take care of the alternatives. It's a very easy one to rebuild yourself. The wp rebuild kit is about the same cost ($100) as having an alternator rebuilt.

    Pulling the alternator is next easiest after the WP.

    You're right about the belts tho. Anything belt related is a minimum of a couple of days. Just getting stuff out of the way & reassembling it again is 2/3 to 3/4 of the work.

    Timing drive repair can be in a class to itself.
     
  9. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    10,167
    San Carlos, CA
    Full Name:
    Mitchell Le
    Verell would be in a position to know this, this week, isn't it?
     

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