Transmission Flush Question

Discussion in 'Chevy Truck Forum' started by DannyCO, Jan 29, 2016.

  1. DannyCO

    DannyCO Full Member

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    The lube places always want to get me to do a transmission flush. I always decline. My thought are the changing the filter and a few quarts of fluid is better than a flush that may cause more harm than good. What are your experienced opinions on transmission flushes?

    Thanks, Danny
     
  2. Bad88

    Bad88 Full Member

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    Hi Danny. I have never had it done. I do no know how they an flush all the valves. Maybe it is better than nothing though.?
     
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  3. leolkfrm

    leolkfrm Full Member

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    have had flush done on a couple of cars, think it helped.... allision is a exterior filter change on gmc....

    cooling line rotted out on the beater lost 7 quarts, guess that make it a fluid change lol....:rofl::rofl::rofl:
     
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  4. mowfixer

    mowfixer Full Member

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    I think it helps if done at intervals of 25-30K miles and started when the vehicle has low mileage and if done by a reputable transmission service place. If you take a worn out transmission and flush it you might be signing its death notice. And if you go ta a hack mechanic he might just pump the fluid out the dip stick and charge you for a flush.

    My new car gets a flush at the dealer every 30 K and I hope it helps down the road.

    This is one of the most debated subjects in car repair on the web.
     
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  5. DannyCO

    DannyCO Full Member

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    I know! I have been researching it and have found widely different opinions!

    While I think changing ALL the fluid would be a good idea, I don't think the methods I have found on the web would do much good. The best way in my opinion is where they disconnect one of the cooler lines and let the engine run. They put in as much new fluid as comes out. However, this does not change ALL the fluid and can waste a lot of new fluid. They take a quart out and put a new quart in. The next quart they take out has mostly old fluid but some new fluid mixed in. The more they replace, the more of the fluid is new. Just my thoughts.
     
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  6. kbrown11

    kbrown11 Full Member

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    Once I was told that if I have over a 100k that its best to leave it alone. I also heard that if I wanted to do it just change the fluid and not the filter. I have heard alot of things ha ha. I did do it on 2 trucks that had lower miles. I don't know if it helped but both trucks lasted over 250K miles on them without any transmission problems. One was a 1997 K2500 that had 114K miles on it when I changed the fluid and filter (I stripped one transmission pan bolt). The other was a new body style 1999 Silverado 1500, this one I took to a transmission shop and they did the fluid and filter for $99.
     
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  7. hatzie

    hatzie Full Member

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    #7 hatzie, Jan 29, 2016
    Last edited by a moderator: Mar 17, 2016
    Personally I wouldn't put anything other than transmission fluid in the transmission. Introducing a cleaning solvent is asking for trouble IMHO. Just say NO.
    If you want to do a complete drain and re-fill that fills the torque converter with fresh fluid;

    1. Drop the pan and change the transmission pickup strainer "transmission filter".
    2. If you don't want to keep wearing tranny fluid every change weld/braze a drain plug into your pan or replace it with a pan that's got one already welded in.
    3. Re-install the pan.
    4. Refill the pan with Dexron VI.
    5. Remove the upper cooler (return) line from the radiator and add a section of rubber hose that reaches the bottom of a bucket of fresh Dexron VI.
    6. Add a section of temporary hard line to the upper radiator cooler fitting and put the end in an empty waste oil bucket.
    7. Chock all four wheels front and back.
    8. Have SWMBO or some other assistant set the parking brake, start the engine, and put the transmission in drive.
      • If the level of fresh fluid in the bucket doesn't immediately start to drop you'll have to put a fitting in the cover to attach the temporary return hose and place the bucket O fluid above the return line to push fresh fluid back to the transmission... or make some other arrangement to accomplish the same thing. I've actually seen guys just pour 9 quarts in the dipstick with the engine running and the cooler open to the drain bucket.
    9. As soon as the fluid flowing into the spent fluid bucket looks clean and red have your assistant kill the engine.
    10. Remove the temporary hoses and re-install the trans cooler line into the radiator.
    11. Cut a section out of the return line that matches the length of a Magnefine Transmission fluid filter.
    12. Install a Real Magnefine filter in place of the section of return line you removed. There are some dubious quality Chinese ripoffs floating around that have shells with a tendency to burst and shatter. Raybestos is selling one of these ripoffs. The real deal is made in Australia by Boss Products. They tell on their web-page how to identify ripoffs. I just order direct from their US presence here --->Magnefine Filters--Online Order Form
      • I do not trust the cheap hose that comes bundled with inline filters... Use Real SAE J1019 Transmission and Oil Cooler hose. SAE J1019 hose is available from the major players like Gates. J1019 is printed right on compliant hoses. Why use it? J1019 Compliant hose is reinforced with a burst pressure of more than 250PSI and the inner liner will put up with -40 to 302°F transmission oils.
      • Use Fuel Injection hose clamps or properly sized Constant Tension Spring Band Hose Clamps DO NOT USE SMALL DIA WORM DRIVE CLAMPS the small size worm drive clamps can't provide sufficient clamping force to prevent leaks and they cut into the hose outer jacket.
    13. Start the vehicle again and set the tranny in Neutral. Warm her up to operating temp and top up the tranny pan with the pint or two of Dexron VI you need.
    14. Go to your handy dandy AutoZone or the like and get rid of your spent oil.
    15. All done.

    Change the magnefine filter once at 5,000 miles and then every two or three oil changes, I do 5K oil changes so that's 10,000 or 15,000 miles or so between trans filters, and top up the pan with Dexron VI to make up for the half pint or so that drained out with the old filter and open cooler.
    Change the fluid every 20-30,000 miles if it looks darker than fresh fluid.
    With a real 25 micron filter in the cooler return line the 100 micron strainer will not need service for the life of the transmission but you can change it out every 100,000 miles if it makes you feel better.

    TSB 08-07-30-040B was released for the 4L60(E), 4T40, 4T45, 4T65E, & 4T65E-HD transmissions to inform techs to change the cheapo low temp magnet GM installed at the factory out for one or two that actually still have a magnetic field at the 180-230°F normal transmission operating temp and add one more of the same to the strainer on the 4T65E & 4T65E-HD. It probably wouldn't hurt to do the same on the 4L80E, TH700R4, TH350, & TH400. I've seen people put rare earth super-magnets on the outside of the transmission pan. Not sure how effective that is... but they don't come off and I bet they gather some fine metal shavings inside the pan.

    Here are a couple videos showing exactly what makes it through the OEM Transmission "Filter".
    [video=youtube_share;WbPM0hW9DmQ]http://youtu.be/WbPM0hW9DmQ[/video]
     
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  8. DannyCO

    DannyCO Full Member

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    Great info hatzie! Thanks!
     
  9. hatzie

    hatzie Full Member

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    #9 hatzie, Jan 30, 2016
    Last edited by a moderator: Mar 17, 2016
    This guy installed a ZF allen head drain plug and a mating 14mm Jam Nut from his junk drawer in his 4L80E pan. The dimple is there for a drain plug on this pan but was not installed by GM.
    The only thing I might do differently is screw an M14 bolt tightly through the Jam Nut, pre-drill a hole in the pan to clear the bolt threads and, tightly install a Nut on the inside of the pan clamping the Jam Nut forcibly against the pan for welding. The bolt will also keep any weld spatter out of the threads and hold the Jam nut centred on the hole. The extra nut and bolt can be removed after it's finished.


    Metric Jam nuts will give you the lowest profile
    Parker Hollow Hex Plugs from Grainger Industrial --->PARKER Hollow Hex Plug,M16 x 1.5,Metric - Carbon Steel Pipe Fittings - 39A343|VSTI16X1.5EDCF - Grainger Industrial Supply
    VW-AG Metric Allen Head flange head drain plug. M16x1.5 from ECS Tuning --->https://www.ecstuning.com/ES2622740/?gclid=CNSsrsqg0soCFcZbfgodidoCGA
    Steel Metric Jam Nuts for welding to steel pans.-->https://www.belmetric.com/metric-jam-nuts-zinc-plain-jam-nuts-c-3_279_1297.html

    SAE will be a higher finished profile unless you machine your own pan fitting.
    Moroso SAE 3/4-16 Allen Head Drain Plug With O-Ring Moroso Drain Plugs 97006 - Free Shipping on Orders Over $99 at Summit Racing
    SAE 3/4-16 Jam Nut QA1 Jam Nuts JNR12S - Free Shipping on Orders Over $99 at Summit Racing
     
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  10. 96silverado

    96silverado Full Member

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    Never, Nadda, nope to such..
    just changed tranny oil&filter my entire life.
     
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