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Tranny fluid exchange

Discussion in '80-Series Tech' started by squeezer, Dec 10, 2003.

  1. squeezer

    squeezer

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    First...its home...its finally home ! After 3 months of searching We are the proud new parents of a 96. White on tan locked and loaded. woo hoo !!!!

    Now for my question. I am going out to the garage to start a full synthetic swap ($211 worth of Amsoil...ouch) and am wondering the correct procedure for the automatic. I have used a procedure that has you remove the pressure line to the ATF cooler and pump old fluid out then refill on domestic trannys before. What is the recomended way on the cruiser ?
     
  2. MTNRAT

    MTNRAT SILVER Star

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    Congrats,
    Sean
     
  3. Cruiserdrew

    Cruiserdrew SILVER Star

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    I have always been leary about wholsale flushing of tranny fluid. I would just drain and replace the pan contents (about 4 qts). Do this at each oil change for a year and you have swapped out a large portion of the fluid. I did this when I first bought the truck with Mobil 1 ATF and now do it once per year. I did the calculation once and am at 92% synthetic ATF. That's good enough for me and the switch was gradual for my tranny. Now, maybe it's an old backyard mechanics tale that a complete flush can cause tranny problems but it made some sense to me and so I did it gradually. Is the current fluid burned looking or smelling?
     
  4. DanKunz

    DanKunz SILVER Star

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    If you flush using the onboard pump you run no risk...if you power flush you are asking for trouble.


    I had the opportunity to drop my whole pan so I got a lot out of mine last time I serviced it.

    Cleaned the screen too :flipoff2:
     
  5. Sailfish

    Sailfish

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    I had my 1996 LC power flushed at Toyota Dealer - $99 plus tax - on special. Also power flushed cooling system with Red fluid. It's been almost a year already and no problems. Toyota didn't seem to think it was an unneccesary risk and they gave me the option to drain-n-fill before we did anything.
    When the time comes, I will power flush again. 8)
    Also, using Mobil One over Amsoil - better price and wider availabilty.

    Congrats and best of luck with your new rig. IMO, 96 TLC is one of the best models ever made - period.[flash=200,200][/flash]
     
  6. instigator

    instigator

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    the line you want to remove is the line that crosses the main pulley,the line going from the pair of hard lines directley into the radiator cooler. the fluid will flow from the hose into what ever you have to collect the fluid. i did mine with a graduated contaner to show how much to put back in, takes about 15qts to flush it all out. but first drop the fluid from the pan and start fresh from there.
     
  7. Pitbull

    Pitbull

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    I've had it done several times but alway with a machine. Also used Mobil synthetic ATF and never used the flush. Just do the fluid exchange. I understand that you can do it with just a bucket and pouring fluid in as it sucks fluid out. The only thing I would worry about that is I wanted to make sure I was getting enough in as the old was going out and the machine does that. I used 15 qts to do the exchange. I would find a shop with the machine and supply your own fluid. I think it will be safer. Congrats on the new LC
     
  8. Beowulf

    Beowulf

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    I thought we lost you for good when we sneaked out of SOR when you weren't looking.
    -B-
     
  9. IdahoDoug

    IdahoDoug

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    I recommend against even a fluid exchange. The issue with chemical power flushes has been well explained - never do this. But a complete fluid exchange has it's dangers as well. Here's why.

    AT fluid has a very high detergent level to keep dirt moving and out of delicate valve bodies and tiny orifices so it ends up on the filter or settled on the pan. The 'dirt' is really metal dust in the main, of course. Over time, the detergents wear out and pockets of deposits collect and settle in grooves, corners and other areas of slow/low flow.

    If you do a few drain/refill cycles, you're adding a gradually stronger replenishment of the detergent which will gradually dissolve these pockets in a way that is going to have a small amount of solids circulating in a diluted form. If you completely renew 100% of the fluid, the strong level of detergent may cause these accumulations to come off in chunks that might block a small orifice long enough to ruin a valve, or permanently block it. This would be a huge issue on tranny that has been regularly drained, but not had it's filter and pan cleaned yet. I'd NEVER do a 100% refresh if this is the case. Conversely, it would make little sense to do a 100% refresh without doing a pan/filter cleaning at the same time.

    If the tranny fluid has been regularly replaced, these accumulations won't stick places other than the filter and pan as designed. So if you know the history it may be something you're willing to do. But if you're wrong, it could end up costing big bucks to tear down the tranny over a glob of semi congealed metal paste that could have been slowly dissolved with a slow strategy.

    Literally this very day, my brother in law changed his mind on a fluid exchange and had the pan dropped, filter cleaned and the normal 6.3 quarts replaced in a normal drain/refill sequence.

    DougM
     
  10. cruiserdan

    cruiserdan SupportingVendor Emeritus Moderator

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    Oh, Dr Doug Doom, ;)

    I respectfully dis-agree with your view of an exchange. Afterall you are not dumping a cup of Tide into it. ;) I have done mine twice using that method and unless you find ATF pouring out of that hole in the front of my block( :flipoff2: ) . I'll continue to do so.


    :cheers: D-