Thoughts on flushing rather than pan drop...

Discussion in 'GM Powertrain' started by dedmon27, Apr 7, 2012.

  1. aloxdaddy99

    aloxdaddy99 Epic Member 5+ Years 1000 Posts

    I have only flushed my tranny's at Jiffy Lube. I have never had an issue. The reason I went with the flush instead of just dropping the pan and changing the filter is you actually get a more complete fluid change. I do understand not wanting to push the junk from the bottom of the pan into the tranny and it's cooler. If there was a way to get a more complete fluid change with just dropping the pan I would go that way.
  2. 08_rado_rocker

    08_rado_rocker Member 2 Years 500 Posts

    I can see the valid point in this. Gave me an idea that hasn't been brought up yet i dont think.. how bout you drop the pan and upon completing that, flush it? would prevent crap from the pan from getting to other areas of the transmission, and would give the "more complete" fluid change feel also. As far as being cost-effective.. i dont think so haha.. but just an idea.
  3. SurrealOne

    SurrealOne Former Member ROTM Winner 1000 Posts

    This implies that there's not other metal shavings elsewhere in the transmission that you'd be shifting around. But there are. Key to the concern with flushing is avoiding pushing things that are fine in one location ... into another location where they won't be fine.
  4. 08_rado_rocker

    08_rado_rocker Member 2 Years 500 Posts

    lmao... it was more of a joke than anything. I'm firm on my drop the pan standings. But i do agree with you. and also my "Idea" is a little ridiculous, lol.. as you would have to drain/drop, then refill to drive to get the flush, have the flush performed.. just a little overkill to me haha.
  5. dedmon27

    dedmon27 Rockstar 100 Posts

    Something just crossed my mind. Lets think about this. OK when they flush the transmission they go thru the lines either at the cooler at the front of the truck, the lines that go into the radiator, or where the lines go into the transmission itself. The machine that the quick change place I go to uses a T-Tech machine, one the uses the actual transmission pump to push out the old in pull in the new. Now that being said would it really dislodge any type of shavings etc., because if it would, then when your driving down the road it would be flowing debris thru the lines as well. So that being said I would like to hear more thoughts about this.
  6. GMCZ71

    GMCZ71 Rockstar

    I get a transmission flush every fall on my truck with no issues and she has 248k miles on her. I do have a post in here about an issue that I am having with it but I think that's because she has 248k on the original transmission
  7. Working at a shop that does tranny flushes every day, flushing it is a good way of keeping it clean. Our machine flushed everything including the filter and torque converter. I flush mine and i recently dropped the pan and changed the filter after i flushed it. I've noticed that is the best way because you arent getting all the old fluid through a brand new filter just my 2cents
  8. moogvo

    moogvo Epic Member 5+ Years 1000 Posts

    Fishing is ALWAYS more fun than dropping pans... A lot quieter too.

    Oooooh! You said "FLUSHING"... My bad!
  9. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner 1000 Posts

    I think it depends on how you are flushing. since you are talking about doing this at short intervals between filter changes and not in place of there are ways to do it and not sure how it could be dangerous. Besides a pan drop and filter change only gets about 40-50% of the old fluid out.

    Here is how I was advised to flush (did this after the pan drop and filter to remove remaining old fluid)
    1) Mark a large clear container with a line at 1 qt (I used a cleaned milk jug and a measuring cup. filled with 1qt water and marked jug. emptied then dried)
    2)Get a 3/8" ID diameter hose (vinyl, rubber etc) to put on the end of the tranny line. About 2-3 feet depending on the height of the truck
    3)Disconnect return line (I did mine on the line from tranny to radiator at the radiator end as I couldnt get the one from the cooler to the tranny without dropping the exhaust so there was probably about 1/2qt of old fluid left).
    4)fluid level should be full or close to it in tranny and have enough ATF on hand for full capacity (I used about 5 quarts on the filter change so I had another 3 1 gallon jugs of ATF. and full capacity is 13.5 in the 4l80e so I only needed roughly 9 more qts)
    5)With line disconnected and hose running from line in to container. With the help of a partner start the truck, then turn off when fluid level hits 1 qt (took about 15 seconds on my truck). 1 person watches fluid level other is doing the key.
    6)Add 1qt of fluid at dipstick
    7)transfer used ATF to whatever container you store your fluid in so that the measuring container is empty then repeat steps 5&6 until ATF comes out clean and new (for me I did about 9 cycles. 9+5 (initial fill) = 14). If you were doing this between recommended filter intervals you would go full capacity.
    8)Re-connect transmission line
    8)Check the cold level (if on dipstick) to make sure that the fill is close otherwise add to correct level. Drive vehicle and bring transmission to temp and check fluid level and bring to appropriate level if needed.

    This method requires no pumps other than vehicles and is doing no cleaners just replacing the fluid that is in the torque converter, so no gunk is going to break loose that isnt going to do it under normal conditions which is most warnings against flushes.
  10. aloxdaddy99

    aloxdaddy99 Epic Member 5+ Years 1000 Posts

    That seems a bit time consuming. But not as much as a tranny swap. I may start to use this method in the future. Thanx for the tip.

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