2000 Subaru Outback Overheating

Discussion in 'Subaru Outback' started by Jake, Jul 23, 2006.

  1. Jake

    Jake Guest


    I live near the Rockies. When I travel up to the hills, my Subaru
    tends to overheat when the car shifts into overdrive and back. If I
    back off, the guage goes back down to the normal range. I also see
    this problem around town, again if I go into overdrive.

    I took it to a repair shop. They said they tested it and said
    everything looked normal. Unfortunately, I was in to get something
    else repaired and am not sure what "tests" were done.

    Any thoughts?
    Jake, Jul 23, 2006
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  2. Why don't you get a mechanic to fix it? ASE certified, BBB Approved.

    A lot of things can cause this overheating. Electric fan switch,
    temperature sensors, malfunctioning ECU, Blow-By, cracked cylinder
    head, leaking/ blown head gasket, old radiator fluid, clogged radiator,
    bad water pump, etc etc.

    Because you live in high altitudes and drive around in severe heat in
    middle America, your car is put under exceptional additional stresses
    that it otherwise would not by under if you lived on the West Coast for

    The high altitude/low pressure puts additional strain on the
    radiator/cooling system. The difference between inside and outside
    pressure on the radiator is drastically increased due to the high
    altitude. Result? Shorter cooling system lifespan. Shortened engine
    life. All of which is further exasperated by the freezing winters and
    hot summers of the rockies.

    eastwardbound2003, Jul 24, 2006
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  3. Hi,

    If I got this right, your overheating occurs in overdrive, then it cools
    down in drive? That sounds to me like a lack of coolant flow at the
    lower rpm of overdrive is a "first thing to look at" problem, followed
    by poor air flow.

    Possibilities for poor coolant flow:

    Partially clogged radiator. If you have been using coolant mixed with
    regular tap water instead of distilled, it's possible you're starting to
    develop some scale in your radiator that allows enough flow for "low
    demand" cooling, but not enough for "high demand" situations. At five
    years, you're close to halfway thru the average life of most radiators,
    even when properly cared for, according to several sources. New
    radiators aren't that expensive compared to the damage you may be
    avoiding. Two online sources I've used are www.radiator.com and
    www.radiatorbarn.com. Both have higher capacity radiators than stock for
    some apps. Take a look to see what they have for your car. My preference
    is Radiator Barn for fit and quality. They are a little higher priced,
    but the three trips to the warehouse to get a unit that fit last time I
    used the other guys ate up any price differential!

    Slipping drive belt, IF your water pump's driven by an adjustable belt.
    I don't know how yours works on the 2000.

    Grumpy thermostat: it's open, but not flowing enough coolant. While my
    experience w/ t-stats says they USUALLY work or they don't, I HAVE had
    some that didn't quite get all the way open when they needed to be or
    acted very slowly. This is especially a problem if the car's been
    seriously overheated and the t-stat wasn't replaced after that incident.
    The t-stat could be damaged. Most folks recommend using Subie OEM
    stats--some aftermarket units don't seem to flow as well. If you don't
    go OEM, I've had good luck with Stant Superstats (also sold under the
    NAPA brand as Superstats.)

    Possibly wrong temp thermostat. In today's engines, it's not so likely
    you'll have one that's too high a temp, since so many are running in the
    190-195 deg F (88-90 deg C) range, but there ARE still apps that call
    for a 180 (82 deg C), so if someone put a hotter one in, there COULD be
    some flow problems.

    Possibilities for poor air flow:

    Fan clutch dying, IF you have a fan clutch. The fluid in fan clutches
    does degrade over time, and the fan ends up turning slower and slower by
    the year. You COULD have a clutch that still turns fast enough at higher
    engine rpms but drops off when the engine slows. Just replaced one like
    that last week!

    Bad thermoswitch for an electric fan, or even a dead fan motor (check
    fuses first.)

    Radiator clogged w/ bugs or debris. Get out the garden hose or air hose
    if you've got a compressor and clean it out. Doesn't have to be perfect,
    but get as much crud out of the fins as you can without going crazy.

    And one oddball possibility:

    Wrong coolant mix. Most mfrs recommend 50-50 to 70-30 mixes. Pure water
    cools best, and the cooling ability (not boiling point--actual heat
    rejection capacity) drops as you raise the anti-freeze percentage.
    Contrary to some people's opinion, a 100% anti-freeze level can cause
    overheating! You can get testers at the auto parts store to test the
    mixture level.

    Lots of things to look at, no? Hope you find the problem easily!

    Rick Courtright, Jul 24, 2006
  4. superb post.

    Carl 1 Lucky Texan, Jul 24, 2006
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