transmission slow to change range

Discussion in 'Trucks [ Eighteen Wheelers ]' started by gunner76, Dec 12, 2015.

  1. gunner76

    gunner76 Medium Load Member

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    I've noticed since It's gotten cold my transmission is slow to go into high range when I first leave in the morning. In order to get it to go into high I have to flip the lever back and forth a few times then it will work fine the rest of the day. then after sitting all night it will act up again the first time I try and change the range. There are no leaks anywhere and I'm running synthetic fluid in the trans. Other winters it was a little slow to shift into high but not as slow as it is now and before it usually wouldn't act up until the temps were single digits or below zero. Now it's been doing it when the temps are in the low 30's. Any ideas what causes this?
     
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  3. DaveLV

    DaveLV Light Load Member

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    My first guess is the orings in the range cylinder are getting nasty. If you have your air dryer bypassed or have had it for any amount of time might have let moisture in. The silicone grease will bug up over time when mixed with moisture and any oil residue. That would be the first thing I would look at. Could be as simple as replacing the orings.
     
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  4. BoxCarKidd

    BoxCarKidd Road Train Member

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    Most likely to do with the air control and or slave pistons. If you put something like Marvel Mystery Oil in the lines so it gets to both side of all valves it may correct it temperarerly. Long term you have a reacurring problem and if you do not issolate and repair it will eventually shut you down.
     
  5. Cory wood

    Cory wood Medium Load Member

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    Range selector piston or orings, or slave valve is gummed up. Nothing to major hopefully, what kind of tranny?
     
  6. Ozdriver

    Ozdriver Heavy Load Member

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    True, or just put an O ring kit through them. Too easy.
     
  7. Cory wood

    Cory wood Medium Load Member

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    Depending on the tranny it's easy. Fro series you have to take the shift top off
     
  8. gunner76

    gunner76 Medium Load Member

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    it's a RTLO 13spd(if memory serves me). I'll check into the o ring kit.
     
  9. Cory wood

    Cory wood Medium Load Member

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    Nov 7, 2015
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    That's easy then, should be right on the back of the tranny upper right side
     
  10. Pool6710

    Pool6710 Medium Load Member

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    my truck has done this for years. Just flip it from low to high and wait for it to click in. Put it back in low and it works normal. Don't worry about it.

    When it gets to -20 it sometimes takes a bit.
     
  11. bavarian

    bavarian Heavy Load Member

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    Feb 13, 2014
    Winnipeg
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    I had the same problem. It got worse as colder it was. The problem was solved as I put an overhauled tranny in. The oilcooler leaked coolant into tranny. I know the leaking cooler had nothing to do with the slow changing ranges when cold but was solved with the other tranny.

    If it could be fixed by a few O-rings, I'd go with it.
     
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