Gurgling and Sizzling Sound - Changed Trans Fluid

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by RexPrius, Jan 5, 2013.

  1. RexPrius

    RexPrius Junior Member

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    Hi folks,
    Today I changed the transmission lubricant (the oil not the coolant) on my 08. The drain plug was pretty tight, and it loosened up with a loud snap. Immediately after the snap, I heard liquid gurgling followed by a sizzling sound (like water hitting a hot skillet). The sound stopped after a short while, <1 min.

    I proceeded to drain and refill the transmission lubricant. When I drove the car after the work, everything was normal. Does anyone have any idea what caused the gurgling/sizzling?

    Prior to the trans lubricant change, the engine had been off for days except for the minute or so that it took to drive the car up on ramps.

    Thanks.
     
    #1 RexPrius, Jan 5, 2013
  2. jdcollins5

    jdcollins5 Senior Member

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    Did you remove the fill plug prior to removing the drain plug? If not that may explain the gurgling sound. I have no ideas on the sizzling sound.
     
    #2 jdcollins5, Jan 5, 2013
  3. RexPrius

    RexPrius Junior Member

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    The fill plug was still closed when the noises occurred. The noises happened after the drain plug loosened but before it was removed and before any trans lubricant started draining.
     
    #3 RexPrius, Jan 5, 2013
  4. bisco

    bisco cookie crumbler

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    maybe you heard a prius noise at the same time you were loosening the plug and thought they were associated?
     
    #4 bisco, Jan 5, 2013
  5. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes. What you heard was air entering the drain hole as fluid was coming out. When the transaxle is cold, there is a partial vacuum inside. As the transaxle heats up to normal operating temp, the heated air inside the case expands and a vent allows excessive air pressure to escape. Then when the transaxle cools down, a slight vacuum results.
    I recommend that you remove the fill plug first. This is a practice that you should always follow when replacing transmission, transaxle and axle fluids. Had you done so when the Prius transaxle is cold, you would hear the rush of air entering the fill hole.

    The reason for that practice is that if you should find that you are unable to remove the fill plug for whatever reason, you will be in trouble having already drained the old fluid. Then you get to tow the vehicle somewhere to seek professional help.
     
    #5 Patrick Wong, Jan 6, 2013
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