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4L60E Fluid/Filter Change n Flush

Discussion in 'Chevy Trucks' started by ieetgluu, Jan 10, 2012.

  1. ieetgluu

    ieetgluu Member
    Messages: 47

    So I bought my 2003 GMC Sierra 4.8 4x4 with about 72k miles on it about 3 yrs ago. It has about 120k on it now. Im thinking about doing a fluid and filter change as it hasnt been done to this truck atleast since Ive owned it.
    Im looking for any info and advice on how you guys are flushing the TC i.e. which trans cooler line to pull and how you are performing the flush. I do most of my own maintenance and work and like usual Im doing the research first. Ive read plenty of peoples opinions on the subject, but have seen few write ups and videos on the actual flushing of this transmission. Opinions are certainly welcome, I dont mind reading them again :)
    The truck has the 16 bolt deep pan and drain plug that will probably be a PITA. Im fairly certain on the pan drop and filter change procedure itself. I also reserve the plan to leave the old filter seal in as I see that it can also be a PITA and may not be nessecary to change based on its condition.
    Thanks for your replies
     
  2. Jacobsmovinsnow

    Jacobsmovinsnow Senior Member
    Messages: 315

    When I change tranny oil , I replace the filter, put the old oil back in and add new oil as necessary. All new oil is hard on the clutches/linings. This was advice given to me by a experienced mechanic year ago
     
  3. 97S104x4

    97S104x4 Senior Member
    Messages: 153

    i have also heard from many mechanics that they dont like changing tranny fluid after it hits 100k miles. if you do its kinda hit or miss if its gonna give you problems or not
     
  4. ieetgluu

    ieetgluu Member
    Messages: 47

    Thats more or less why I havent done mine yet. Scared by the ole auto trans hear-say.
     
  5. theholycow

    theholycow PlowSite.com Addict
    Messages: 1,180

    It's an old wives' tale. People with failing slipping transmissions decide maybe throwing some new oil at it will fix it, but the old oil full of worn-off clutch material is all that was holding it together...people with good working transmissions don't have a problem unless some silly reverse-force-flush machine was used, but nobody uses those anymore.

    I was scared due to high mileage but I went ahead and did the backyard pump-out complete fluid replacement on mine. I'm glad I did.

    A decent howto thread:
    http://www.gmfullsize.com/forum/showthread.php?t=179148
     
  6. wirenut

    wirenut Senior Member
    from nh
    Messages: 513

    exhaust

    does the exhaust have to be dropped on a 04 z71 to get the pan down ?
    thanks
     
  7. ieetgluu

    ieetgluu Member
    Messages: 47

    No, if that were the case, I wouldnt be considering doing this. Of all the stuff I did on my 88 Silverado, the exhaust/Y-pipe was often the most frustrating to deal with. Funny though how I could get its manifolds on and off if needed, but my 03 manifolds are blocks of flaky rust. I dread the day I or my wallet has to deal with those things...
     
  8. ieetgluu

    ieetgluu Member
    Messages: 47

    That is a good how-to. Im only confused on at what point was the filter change worked in to the flushing. As it is written(step by step), it was completely flushed, then filter changed. But it almost seems like he would have flushed the first 3-4qts. out, then dropped the pan(little fluid should be left in it?), changed the filter, replaced it all and continued to flush the rest.
    He also mentions later on the he swaps out his rad. for one w/ TOC provisions. I already have a factory external tranny cooler and I wonder if it changes the flush point at all? Probably not, Im just good at over thinking things sometimes
     
  9. ieetgluu

    ieetgluu Member
    Messages: 47

    Also, do you know if that p/n 24208576 is for shallow pan or deep pan?
     
  10. theholycow

    theholycow PlowSite.com Addict
    Messages: 1,180

    Keep in mind that it's all mixing while you pump it out, so if you pump out 3-4 quarts then drop the pan that doesn't mean the pan has all the remaining old stuff. Doing the entire job until it comes out clean and then dropping the pan wastes a little bit but replaces as much of the fluid as you could want. You could also drop the pan first but then you expose your new filter to old fluid.

    I was going to open mine at the cooler output like you're thinking of doing, but I had corrosion problems so I did it at the radiator. IIRC I was going to use the passenger side of the cooler.
     
  11. When I did my '04 2500HD I dropped the pan and changed the filter. I then disconnected the return line on the side of the tranny and attached a piece of heater hose and ran it to a drain pan. I put in 6 qts of new fluid and ran the truck for about 30-45 seconds. I continued this process (adding a couple qts at a time) until the fluid coming out was fresh and red. Thats how you get all of it out. I think I used an extra quart or two but it's well worth it.
     
  12. JimACM

    JimACM Junior Member
    Messages: 23

    This video was some help to me in changing my filter

    http://www.youtube.com/watch?v=6THHOWxyV6I

    Even though he did not remove the shift cable bracket it is better to remove the two t40 bolts as the pan goes back in a lot easier. I removed the clip like he did and couldnt get the pan with gasket back in. There is really only 1 bolt that is a problem it is a 10 mm and I used a combination ratchet wrench like this
    http://www.gearwrench.com/catalog/wrenches/ratcheting/flex_combination/

    With the front up on ramps I got 5.5 quarts out of my 4L85 trans
     
  13. wirenut

    wirenut Senior Member
    from nh
    Messages: 513

    i tried today to change filter and couldnt get pan off without dropping exhaust...needless to say i didnt do it as i didnt want to break studs....
     
  14. ieetgluu

    ieetgluu Member
    Messages: 47

    Was the pan catching on the filter or something? I havent done mine yet, but Ive been under my Sierra which should be identical to your Z and I cant see where the issue would be. That, and Ive never read of that issue nor seen it in any of the youtube 'procedure' videos Ive watched. However I can certainly relate, it seems like it's always something that doesnt go as planned. Im sure New England corrosion will bite me when I do mine...it always does.
     
  15. wirenut

    wirenut Senior Member
    from nh
    Messages: 513

    i guess there are two pans, a deep one and a regular. and mine is deep
     
  16. ieetgluu

    ieetgluu Member
    Messages: 47

    Yes so is mine, hope I dont run into that
     
  17. zr900

    zr900 Junior Member
    Messages: 26

    I just dropped the pan on my 99 Silverado new body style about a month ago and was able to get the pan off without removing the y pipe. But when I put the pan back on I managed to unhook the solenoid connectors so the pan had to come back off. I pulled the Y pipe and it made life much easier.