`95 Legacy L with 'whine' & weird smell.

Discussion in 'Subaru Legacy' started by Bradley Walker, Jul 18, 2006.

  1. Hello all,

    My mom called me from work earlier today regarding an issue that started
    happening with her legacy L wagon. On her way to work she first heard what
    she described as a high pitch/whine noise coming from the engine
    compartment. While she was at work, I took it to the dealership and on my
    way there, I could hear a a similiar noise. It reminded me of what happens
    when a belt is too tight around a pully and the noise it makes when the belt
    is rubbing hard against a pully.

    The second issue was that there was a "heavy chemical smell" coming from the
    engine compartment blowing back in the window. I too smelled this and the
    closest description I can give is that it is a mixture of a burnt belt/hose
    smell mixed with that of a chemical nature. I was running things through my
    head of what it could be and did a visual inspection but couldn't see any
    belts that were tearing/cracked/broken or any hoses that were torn or loose.

    When I arrived at the dealership to schedule an appointment and leave it for
    them over night to diagnose, the service manager hopped in the car and
    revved the engine up to around 3-4k rpm. When he did that with the hood up,
    I could once again hear the whine and smell the smell. It seemed to
    originate somewhere from the middle to the front/middle of the engine
    compartment. Upon closer inspection he and I both could smell that smell
    coming from the alternator area. His first reaction was that the alternator
    was burnt out.

    I do know in recent weeks with my mom's car, that when starting it, I have
    to hold the key in the ignition position for an extra 1/4 of a second for
    the engine to start. It seems like putting these things together could be
    the cause of that. My mom also reported this morning that when she sat in
    stoplights the car acted as if it was wanting to 'give out' while idling.
    When she said that, I was wondering if it might not be PCV valve related.
    The dealership had flushed the carbon out of it last year, rather than
    replacing it when it was having idling problems and wanting to idle to idle
    to halt.

    Anyone here have thoughts/ideas/suggestions?

    Brad
     
    Bradley Walker, Jul 18, 2006
    #1
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  2. Bradley Walker

    Frank Guest

    One potential source of smell is grease or oil leaking on exhaust
    system. This happened to me and is easily seen by looking underneath
    for burnt spots on exhaust.
    Car could have multiple problems.

    Frank
     
    Frank, Jul 18, 2006
    #2
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  3. Bradley Walker

    Jim Stewart Guest

    Shorted alternator diode will cause a whine
    and might very well cause the smell.

    Typically, a shorted diode will still allow
    the alternater to charge the battery marginally,
    but at the same time will discharge the battery
    quickly if the engine is not running. Have you
    had to jump the car lately?

    A tech can sort this out pretty quickly. He
    needs to disconnect a battery cable and measure
    the current with the engine off. I would expect
    a reading of 1's to 10's of milliamperes if the
    alternater is good and something like 2-3 amperes
    if it has a shorted diode.
     
    Jim Stewart, Jul 18, 2006
    #3
  4. It's definately a bad alternator. The dealership called and are replacing
    it for $233 (including labor). The car hadn't needed a jump at all as far
    as I know, the only indication was that when it idled at a stop light my mom
    said it felt like it wanted to just stop.
     
    Bradley Walker, Jul 18, 2006
    #4
  5. Bradley Walker

    Zootal Guest

    Did the alternator fix the problem? I've worked on auto electronics for
    years, and I've never heard a bad alternator make any noise. They usually
    quietly stop working or otherwise go bad and stop charging, drain your
    battery when off, etc.
     
    Zootal, Jul 19, 2006
    #5
  6. I'll find out today. My mom is scheduled to pick it up around noon, I'll
    definately let you know.
     
    Bradley Walker, Jul 19, 2006
    #6
  7. Bradley Walker

    Jim Stewart Guest

    It's a good troubleshooting key. A shorted
    alternator diode causes the alternator's
    rotor to "cog" since rotation of the shaft
    will be much more difficult as the rotor's
    magnetic field moves across the winding with
    the shorted diode. The cogging is what causes
    the whine.

    The bad smell was probably from that winding
    cooking, since it's full output was being
    short-circuited by the diode.

    Often, the battery will go dead since the
    shorted diode provides a path for battery
    current through the winding even when the
    engine is stopped. The diode normally functions
    as a one-way valve allowing power to charge
    the battery, but not to flow back into the
    alternator when the engine is off.

    You used to be able to replace the diode
    pack for about $30 in parts. I haven't
    had to deal with the issue for 20 years
    so I don't know if you could still buy
    one. The job is pretty labor intensive
    so I doubt that you'd see many shops doing
    it anymore.
     
    Jim Stewart, Jul 19, 2006
    #7
  8. That was the correct issue, however this happened once to my mom a month ago
    but the issue went away. It didn't reappear until yesterday and was
    verified as being the issue by the shop. She was billed for $239 for labor
    and an entirely new alternator, not just the diode.
     
    Bradley Walker, Jul 20, 2006
    #8
  9. Bradley Walker

    nobody Guest

    I'm not 'directly' a mechanic; but I've seen about every version of
    alternator failure at work. (I'm a two-way radio tech)

    Alternator problems often show up as two way radio problems because many
    failures produce "dirty" power that drive microprocessor-controlled
    transceivers batshit. Most people don't realize that alternators *do*
    have brushes (riding on sliprings) because they don't usually wear out.
    "Chattering" brushes can make ungodly audible noises that also produce
    massive amounts of electrical noise.

    Depending on belt wrap and position; a shorted diode can cause little
    "stalls" as the rotor turns that can cause a squeal that's sort of like
    a plain old loose belt.

    My old Jeep would lose seals in the alternator bearings and squeal like
    hell about every two years. (it too spent many hours trying to be a
    submarine;}
     
    nobody, Jul 22, 2006
    #9
  10. Bradley Walker

    felixc Guest

    Two Subaru Legacys, three alternators with the whining problem. It
    seems that this alternator has a design flaw. (a fourth alternator
    broke the usual way: worn-out brushes)

    Yes the whining problem is a shorted diode. I opened up one alternator
    and found the faulty part. ( Do not try this without having the shop
    manuals, there's a trick.) The shorted diode causes one of the three
    coils to short circuit. Excessive currents flow through this winding.
    It causes the noise by magnetostriction, and it causes the whole
    alternator to overheat, eventually making the rest of the components to
    fail. With the shorted diode, the Failed battery indicator does not
    show in the dash, but the battery will not charge so the car will stop
    after a while...

    As a test I cut open the diode and reassembled the alternator. No more
    noise, no more heat, the battery did recharge. However the remaining
    two diode sets were overstressed and second one shorted after a couple
    of weeks.

    The diodes are press-fitted into plates. Impossible to change one
    diode. Changing a plate? Well, the Subaru dealer was asking more for
    a single diode plate than it costed to have a rebuilt alt. (not at the
    subaru dealer) Alts rebuilt by Delco have a lifetime warranty.

    It is easy to find if your alternator charges properly. Get a $!0.
    digital multimeter, and measure the voltage at the battery posts. If
    the charger works, the voltage will be at around 14.1 volts with the
    engine running.

    Felix
     
    felixc, Jul 26, 2006
    #10
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