Tranny fluid & filter change

Discussion in 'The Garage' started by ozmoses, Jan 25, 2013.

  1. ozmoses

    ozmoses Ride On

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    GMC Savana.

    Is this a DIY or no? Tricks, tips?

    Not talking a flush & fill, just drain, drop pan, filter change & refill.


    Always driven a stick...
    #1
  2. Strong Bad

    Strong Bad n00balicious

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    Automatic trannys in general; most have a screen NOT a filter. Draining does not take into account the large volume of fluid in the torque converter. That's where the flush comes in. Take it to a quick lube joint, saves you the mess and disposal of the used fluid.
    #2
  3. troidus

    troidus Long timer

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    Make sure you have the tools to reach every pan bolt before you get started, plus have the filter, gasket, and fluid in hand. If the anti-drainback valve for the torque converter leaks, you'll dump more fluid than it says you will in the manual, so be prepared for that, too.

    If the crossmember is in the way, have some way to support the tailhousing when you unbolt the crossmember to move it, and make sure you have room to move it without disturbing your temporary support. Unclip the wiring harness so if the tranny slips off the temporary support it doesn't yank the connectors off.

    If the tranny is a 700-R4, note that there is a ridged silicone seal on the intake pipe on the filter and it can stay in the tranny when the filter is removed. You may have to reach up in the hole with something to catch and pull the seal out before seating the new filter. 4L60/80 trannys may be similar.

    Mind your bolt torque and pattern when putting the pan back on. Tranny fluid leaks suck.
    #3
  4. CycleDoc59

    CycleDoc59 Wrench Rider

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    I recently changed out the filter and all fluid in a Chevy 3500 Express van.
    I pushed a bucket under front, disconnected a trans line to the radiator and started
    the truck. As soon at the fluid started to sputter, I shut off the truck and removed
    the pan; washed out pan, installed new filter, poured in about the same quantity of new
    ATF that had been pumped into the bucket (about 4-5 quarts)

    Then I started the truck, shutting it off again as soon as fluid starts to sputter into the bucket.
    Then I reconnected the line and refilled the trans. This changed all the oil in the trans,
    about 2-1/2 gallons.
    #4
  5. troidus

    troidus Long timer

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    When I flushed my Camry trans, I started with a filter change and pan wash (cleaning the metal shavings from the magnets), then disconnected the cooler return line and piped that to a bucket. I then uncapped 12 quarts of fluid, started the engine, and poured in fresh fluid as the old fluid ran into the bucket. I made sure to cycle the gear selector a couple of times while doing this. As I got near the end, I shut the engine off, reconnected the cooler line, and topped off the fluid level.
    #5
  6. ozmoses

    ozmoses Ride On

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    Reason I ask- went to a transmission repair shop who recommended not to flush with 160k miles, only pan-filter-fluid.

    Stopped at a quick-lube joint who advised that they only flush & refill but do not drop pan or change filter.

    So??

    I like the idea of disconnecting a return line and flushing that way. Anything to damage w/ this method by running it dry, for example? Is there a need to bleed the system afterwards ?
    #6
  7. troidus

    troidus Long timer

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    Don't let it run dry or you can damage the bearings. If you see foam in the output, shut down the engine until you can get the pan refilled. Using a clear line from the cooler return to the bucket will help with this.

    The lubrication system is not sealed, so it will bleed air on its own.
    #7
  8. D.T.

    D.T. Difficult but useful

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    It was a PITA on the GMC Jimmy. There is a crossmember that has to be removed just to get the pan off.
    #8
  9. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    The last time I changed the transmission fluid in my Sierra 1500 truck automatic transmission, I siphoned the fluid out using clear tubing pushed down the dip stick tube. The end of the tube was put in a one gallon jug and left for several hours. I didn't change the screen. I don't like getting transmission fluid all over me anymore.

    Edit: For the automatic transmissions I have worked on, I never saw a screen clogged and the mesh is not fine. Some transmissions may have have a different 'filter' though. The ATF fluid is high detergent which carries contaminants, so it is good to replace the fluid.
    #9
  10. CycleDoc59

    CycleDoc59 Wrench Rider

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    No, there's no problem if you shut off engine as soon as the fluid starts to sputter; that means fluid is now
    below the pan pickup. It only takes a few seconds, so it's best to watch while someone else runs the
    engine. You are only doing what the transmission is constantly doing all the time; circulating oil throughout
    the trans and cooler, only you are replacing the old fluid with new. Changing the oil without removing/cleaning
    out the pan and changing the filter is foolish since a clogged filter can quickly starve the pump and damage
    the trans. No matter if it's a fabric filter or a mesh screen, they still clog....there is no by-pass as there is
    for engine filters.

    I have changed the oil/filter in an '05 Grand Carravan which now shows 320K miles on same trans w/no trans
    problems.....
    #10
  11. vtwin

    vtwin Air cooled runnin' mon

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    +1, just did this on a Mustang and the Chevy. I usually pour fresh fluid in while it's running and pumping out to push any old fluid out. As the poster mentioned, once it sputters, turn engine off, reconnect the line, add a few quarts, run and top off. Of course, make sure which line is which so you don't have a big mess on startup. damhik.
    #11
  12. rabbitears

    rabbitears Been here awhile

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    The flush v pan-drop debate is probably only slightly less contentious than the ownership of Jerusalem, and certainly more debated online. ;) There is a theory which circulates widely (but I have no idea whether it's true) that: flushing a transmission will "stir up" all sorts of filings and other nastiness, forcing them from their current quiet resting place back into circulation where they can do damage and cause further problems. Flushing necessarily means that you're not cleaning the filter/screen and removing any metal filings. On the other hand, flushing can be done just by disconnecting two hoses and hooking the car up to a (mostly?) automatic machine, so it's attractive to quick lube franchises who often don't have highly trained mechanics.

    Whether any of the above is true, I have no idea - but that's the version I read a hundred times when I was researching this myself a couple years ago. For my own part, I have a pretty basic mechanical knowledge and less experience but even I was able to (slowly) drop pan etc without too much difficulty. It's not very tricky. I didn't, however, go to any effort trying to drain the rest of the system beyond removing the pan - I was happy enough replacing a large percentage of the ATF and wasn't going to worry about the rest.
    #12
  13. troidus

    troidus Long timer

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    I think it's an and, not an or. Drop the pan, clean the magnets, install a new strainer, fill with fresh, then immediately disconnect the cooler return and pump out the rest of the old fluid while adding new. Anything that gets dislodged ends up in the bucket. It's the best of both worlds. No quicklube place is going to do it, and the dealer will charge a fortune, so just do it at home.
    #13
  14. concours

    concours WFO for 41 years

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    LOL +1 The 8.1L/4L80E in my 2500 'Burban had shift cable bracketry and 3" exhaust snaking UNDER the pan. The perverted CAD designed needs his balls cut off. I have most every widget on the Snap-On truck and it still was a ball buster. YMMV
    #14
  15. CycleDoc59

    CycleDoc59 Wrench Rider

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    That actually works well; if you change what's available in the pan two/three times, virtually all the
    oil will be changed since it mixes. This can be done w/out dropping pan (after the filter has been changed
    the first time) by using a vacuum pump. Same technique works for changing brake fluid by changing the
    fluid in the master cylinder several times over several months. No, it's not as good as a flush-out, but is
    still quite effective....

    The reverse is a bad idea; flushing w/out changing the filter. Because, as you say, old previously stuck-on debris
    can be washed into the filter, plugging it up fairly quickly.
    #15
  16. concours

    concours WFO for 41 years

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    My vehicles always had a 1/8" NPT half coupling TIG welded to the pan after the first fluid change, enabling me to change the fluid every oil change, thereby getting the rest of the oil changed out. $20 worth of ATF was cheap insurance. Of course, still changed filter on schedule or better. SOME modern tranny's have drain plugs in the pan.
    #16
  17. CycleDoc59

    CycleDoc59 Wrench Rider

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    Which brings up a good point; why don't most vehicles auto trannys have drain plugs?
    -For the same reason modern vehicles don't have grease fittings on ball joints or other
    vital front-end fittings; because it all reduces scheduled maintenance. "All you need to
    do with your new vehicle is change oil and run it thru the car wash.." Pretending that
    ball joints last forever or that transmissions don't need servicing usually takes vehicle
    up to 100K or so, and after that you should buy a new vehicle, right? So what happens
    is that junk yards are stuffed with good vehicles except for failed transmissions, and it
    keeps repair shops backed up rebuilding front ends and trannys... The only thing that
    comes close to "lifetime" is the resulting credit card bills. - Rant over.
    #17
  18. H96669

    H96669 A proud pragmatist.

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    100,000 miles...:puke1That's what GM says for my car. But 50,000 in severe service. That applies to me if just for the "hills" part.:rofl

    Easy to get at but sure will get a plug when it warms up enough to do that job. But funny how it went on older vehicles sometimes, change filter/fluid on apparently good transmissions and then soon after they start slipping. Mind you, even slipping you can drive them like that for a very long time with some judicious hand shifting/throttle action. :wink:

    My dad was a transmission specialist amongst other things.....don't touch it if "that old" he would have said.:wink:
    #18
  19. concours

    concours WFO for 41 years

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    Pretty much. I agree. Great example is Dodeg/Jeep continuing to require transmission band adjustment decades after Ford/GM went to long travel servos, and nobody did the service. OFF THE RADAR. OTOH, I'm at 442,000 miles on my VW TDI with original tie rod ends (inner and outer) so, it can be done, using robust enough sized components and quality sealing design.
    #19
  20. Bayner

    Bayner Long timer

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    The majority of trans flush machines are just fluid exchangers. They measure what is being pumped out of the cooler line and return that amount of new fluid to the system through the opposite line. No different than what the tranny does itself. No danger of doing damage with those types. (Excepting extremely high volume output from the trans that the machine could not keep up with). Maybe someone makes a machine that works on a different principle, but I haven't seen it yet.
    #20