To change or not to change fluid

Discussion in 'Transmissions' started by Dixietruck, May 22, 2019.

  1. Dixietruck

    Dixietruck Newbie

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    I have a 98 k1500 with the 5.7 and 4l60e with 124,000 i was driving the other day and thought I felt it slip only to be confirmed with a check engine light with trasmission component slipped codes. It was a little low on fluid so I topped it off in hope it would fix the slipping. The check engine light came back on after 30ish miles and the truck started shifting hard from 1-2. The fluid smells slightly burnt. Should I drop the pan and change the fluid and add some Lucas transmission fix or just pull the tranny for a rebuild.
     
  2. df2x4

    df2x4 Domestics only.

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    Sounds like rebuild or replace time to me. I've never had anything bring back an automatic transmission once it started slipping, and I've killed quite a few.
     
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  3. Dixietruck

    Dixietruck Newbie

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    Have you had any luck with pull a part transmissions
     
  4. df2x4

    df2x4 Domestics only.

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    When I blew up the second 4L60E in my V6 red truck I decided I'd had enough of that transmission and swapped to a junkyard 4L80E out of a truck with 230K miles. Only put around 5K miles on my truck since the swap, but it's doing great so far.
     
  5. skylark

    skylark I'm Awesome

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    Plan for the funeral. That tranny is dying. Trans man in a can won't help. Unfortunately with pick and pull trannies it is a total crap shoot. Most vehicles in the yards have 150k+ on them already and if they haven't had a tranny then they are due for one and those that have are probably about due for round 2.
     
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  6. kewljay223

    kewljay223 OBS Enthusiast

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    i agree that its probably time for a rebuild. mine was toast and i knew it because it would "stick" in first gear waaay longer than it should and then SLAM into second. i had a shift kit and it was always a hard 1-2 shift but this was BAD. Bad enough that under decent throttle, the rear would kick out. if your experiencing similar symptoms, then yeah, full rebuild is unfortunately in order. Sorry for the bad news.

    Your only saving grace MIGHT be the 1-2 shift solenoid which isnt uncommon to get clogged with grime and cause it to stick and not engage when it should. I tried replacing mine which didnt fix it cuz the trans was way more shot than i thought it was, but you may be lucky in that it might be your issue. the solenoid is like 15 bucks and just requires removing the pan. the VB didnt need to be removed, at least on my 80e. might be worth a try since its cheap and can be done in about an hour.
     
  7. Gramps

    Gramps I'm Awesome

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    It’s probably a dying trans, BUT before you get too hasty check out your mass air flow sensor. Dirty or bad maf sensor readings make the computer do weird things, hard laggy 1-2 shifts being one of them.
     
  8. Schurkey

    Schurkey I'm Awesome

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    Yeah, just replace the transmission. There's never, ever been a case where a plugged trans filter caused problems. Same with shift solenoids--they never fail.









    What gear were you in when it "slipped"? What were the exact codes--and--were you using a REAL scan tool to read those codes? Or were you using some consumer-grade half-assed code reader that substitutes generic codes for the real codes?

    It IS possible that the trans needs to be overhauled. Realistically, that's not what I'd expect at 125K miles. I'd drop the fluid and filter, see what sort of debris is in the pan. Unless I had hard evidence of trans failure, maybe replace some solenoids, clean and replace the pan with a fresh filter, flush the converter and cooler by running the engine with the cooler outlet tube flowing into a drain pan. . The trans is due for the fluid/filter service anyway. If that works, you've saved about $1500 dollars. If it doesn't work, you're out about $60 + solenoids.
     
    Last edited: May 25, 2019
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  9. Dixietruck

    Dixietruck Newbie

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    I have always thought about going for 4l80e swap. How big a pain was this. I’ve seen a few write ups but none were all that helpful.
     
  10. Dixietruck

    Dixietruck Newbie

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    I don’t remember the codes hopefully soon I can get back out to it and post. It’s not my daily and I only have time off every other weekend. Any idea of ballpark estimate if I pull the tranny and bring it to the shop for build?
     

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