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Tranny Flush - Good Idea or Not

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 84GMC, Feb 20, 2003.

  1. 84GMC

    84GMC Registered Member

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    A friend recently described how he flushed his tranny without paying $100. He said he removed his cooler lines and with the vehicle running, he left the incoming line in a waste bucket and left the return line in a bucket full of new fluid. He said he used up about 3 or 4 gal.(I forget which) of tranny fluid before he was finished with the process.

    Is this a legitimate way to flush a transmission.
     
  2. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    As far as I know, the intake line doesn't have any suction to it. I believe that the pump in a tranny is only one stage- this means it moves the fluid through the cooling lines by pushing it, as opposed to pushing AND pulling. Does that make sense?

    It sounds to me like your buddy is out to lunch.
     
  3. 84GMC

    84GMC Registered Member

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    Makes sense. I have a felling he was kidding around. I guess he got me to bite.
     
  4. Highlander

    Highlander 1/2 ton status

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    I got this from Amsoils web site

    1. Make sure the fluid is warm. Warm up the car so the transmission is at normal operating temperature. Pull the transmission dipstick (located near the firewall in most cars). Fresh fluid is translucent and cherry red. Some darkening is normal, but if it is reddish brown or mustard color and smells like burnt varnish, it is worn out.
    2. Drain the fluid by loosening the pan. Select the correct Hastings filter replacement based on pan shape and prepare a large pan to catch the fluid. Then loosen each pan bolt a turn or two and loosen one corner more than rest. Drain mostly from this corner.
    3. Finish removing the pan and any gasket material from the pan or case. Avoid scratching the metal and make sure the pan’s gasket surface isn’t bent or distorted.
    4. Remove the old filter. Most transmission filters are held in place with a bolt or two, but some are held by a clip. Be careful to include O-Rings or other seals.
    5. Install a new filter. Use the clips or bolts from the old filter. Be sure O-Rings, etc. are in place. If the filter has a long intake neck, gently push the neck into place without unseating the O-Ring.
    6. Clean the pan thoroughly. Inspect the pan before cleaning. A small amount of fine grey clutch dust is normal. However, if you find metal shavings, there has been transmission damage. Clean the pan with solvent and wipe dry so there is no harmful residue.
    7. Position gasket on pan. Some gaskets have four holes slightly smaller than the rest to allow four bolts through the pan and through these smaller holes to hold the gasket in place.
    8. Hand tighten pan bolts in a criss-cross pattern. After that, use a torque wrench to tighten bolts to proper ft-lbs as per manufacturer.
    9. Refill the transmission using only the amount shown as “refill capacity” in the owners manual or "AMSOIL Product Selection Guide,” using the type of fluid specified for the vehicle.
    10. If doing only a partial fluid replacement, skip to instruction 12 below. If doing a complete fluid replacement, follow the steps in instruction 11.
    11. You now have replaced the fluid in the pan. To replace the fluid in the torque converter and oil cooler also, follow these steps.
    Step 1. Obtain the total system capacity of the vehicle from the manufacturer or AMSOIL. Have this amount readily available.

    Step 2. Disconnect the oil cooler line from the oil cooler. As you may not know which is the pressure side and which is the return side, have both directed so the stream of fluid will be directed toward a receptacle.

    Step 3. With another person, be prepared to add ATF to the fill area as it is being pumped out of the oil cooler line.

    Step 4. Start the engine, and as the old fluid is pumped out, add fresh fluid to the pan.

    Step 5. When either the fluid color brightens or the total capacity has been replaced, shut the engine off and re-attach the oil cooler line. All fluids has now been changed.

    12. Recheck the fluid level. With the car on level ground, set the parking brake and the transmission in “Park” or “Neutral.” Let the engine idle for a few minutes. Shift the transmission into different positions before returning the lever to “Park” or “Neutral.” Check the fluid level again and check for leaks.

    Hope this helps


    Eric
     
  5. caryhenry

    caryhenry Registered Member

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    I was just curious as to how often most people do a complete fluid change. I have only ever done partial fluid changes, and I just wanted to see how many of you actually do a full change.
     
  6. Thunder

    Thunder 3/4 ton status

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    I have done it the way described above. By disconnecting a cooler line draining it into a bucket and running the engine and adding fluid down the dip stick hole till the fluid comes comes out clean. Works pretty good but it can get a little messy though.

    I only do a full fluid change the if the fluid is wore out and burnt.I dont like that old crap in my trannys. A Complete change of all the fluids is usually one of the first things I do when I buy a used vehicle.
    If you keep the fluid in your tranny fresh and clean by regular ATF changes. I dont think a complete fluid flush and change is nessary.
    But if the ATF fluid is bad it is a good idea.
     
  7. CHEVY 4WD

    CHEVY 4WD 1/2 ton status

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    Does anyone know how much fluid a 700R4 holdes?
     
  8. Highlander

    Highlander 1/2 ton status

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    When I did mine I used just over 2.5 gals to flush it but then I have a B&M Deep pan with a very big cooler. As for how much a noemal setup will take, I wish I could help but I can't find where I but that info sorry.


    Eric
     
  9. caryhenry

    caryhenry Registered Member

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    I just did mine today, and I used 11 qts(2.75 gallons). I was told the 700r4 holds 16 qts including the converter.
     
  10. the professor

    the professor 1/2 ton status

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    Sorry guys..
    --
    Flushing by removing the cooler lines is a BAD, BAD, BAD idea
    -
    Oil cooler flow:

    Oil pump;
    valve body;
    converter...;
    out of the converter;
    to the trans cooler;

    THIS IS THE IMPORTANT PART.....;

    From the cooler, it goes back into the trans for lubrication..

    You run the trans with no cooler lines, and you run the risk of destroying the bushings on the mainsaft in very short order...

    If you must drain, drill a SMALL hole in the front of the converter, about 1" from the rim...use a very small pipe plug to plug it back up when the converter drains...with lockups, you can do it toward the rear

    Ford converters drain this way

    Be aware, there is much risk in this operation..you may hit the lock-up internal piston seal, or one of the turbines...

    Or better yet, just drain the oil and refill, and do it again

    If the fluid is that bad you probably need a trans overhaul anyway

    Do cooler line drains at you own risk
    /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     
  11. BigRed89

    BigRed89 1/2 ton status

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    I normally do not do a complete flush of my transmission, instead I replace the filter and whatever transmission fluid that drains from the pan and out of the transmission when the pan is removed. I'm sure that if you follow the Amsoil directions that <font color="orange"> </font> Highlander indicated above, you'll be alright.

    As far as drilling holes in my torque converter, you will never catch me doing that.
     
  12. Chris_T

    Chris_T 1/2 ton status

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    Where exactly does it lubricate after returning? I was under the impression that the return fluid emptied into the pan.
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    As far as drilling holes in my torque converter, you will never catch me doing that.

    [/ QUOTE ]

    If you have a GM service manual, look it up, it's in there. Supposed to use a rivet to seal it.

    Not that I'd do it either, but GM thought it was ok. Ford's idea was good though, they just did it when the converter was made.
     
  14. the professor

    the professor 1/2 ton status

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    It returns to the pump housing, where it is directed into the main shaft..
    --
    It lubricates ALL the internal bushings, clutches and planetary sets..
    --
    It is THE source of lubrication for the transmission internals.. /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif
     

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