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TH350 wont shift

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by EDdaTREE, May 25, 2000.

  1. EDdaTREE

    EDdaTREE 1/2 ton status

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    Just did motor and tranny swap over the weekend on my 76' K/5 and now she doesnt wanna shift past first gear. Been trying to de-bug it before work every day, but you know how that goes, not enough hours in the day.Swapped modulators WED.and messed with vacuum lines.Didnt hook up kickdown cable yet either. Anybody have any ideas? Thanks for any input
     
  2. 6.2Blazer

    6.2Blazer 1/2 ton status

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    You mentioned that the "kickdown cable" wasn't hooked up yet, I think you just answered your own question.
     
  3. hpfire7227

    hpfire7227 Registered Member

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    I don't think the kickdown cable has anything to do with it. Same thing happened on my 74 GMC 3/4 ton (wouldn't shift past second in the beginning, and eventually stayed in first all the time.)...changed the modulator and triple checked everything else. Changed the fluid several times and found some ugly metal shavings. I sent the truck down the road thinking the tranny was fried, which I attributed to high miles and 4.56's. Good luck.

    10 BOLTS O' FUN
     
  4. Eagle86K5

    Eagle86K5 1/2 ton status

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    When you did the swap, did you seperate the motor and tranny or do it as one piece? Tranny mechanic once showed me that you need to be careful when you put the converter on the tranny, better to stand it up and spin it on as there are dogs that need to connect to the different pumps in the tranny. What you will notice is that when you set it on the tranny and turn it a bit it will drop down, most folks stop there, but you need to turn it a few more times and it will drop a second and somtimes a third time as things engage, then you have to be careful it does not move out on you.
    I recall this was brought up because someone else had done the same thing, and because it did not line up it would not shift....just a thought...

    <font color=green>[​IMG]Eagle86K5[​IMG]<font color=red>
    Masonry...It's a Good Thing
    2B1ASK1
     
  5. BillR

    BillR 1/2 ton status

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    I had the same problem with my TH-350. I got it rebuilt and it's fixed. Sounds serious...

    Blazin' in Flagstaff
     
  6. Toad

    Toad 1/2 ton status

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    The valve body is probably stuck. Where did you get the trany from and did it work before? Can you shift into P,N,D,D2,D1? If not do you have the shift selector rod in the right spot?
     
  7. Black89k5

    Black89k5 Registered Member

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    If you can shift it manually to second gear then its definetly the kickdown cable. Because without tht it won't drop into passing gear.
     
  8. Kodiak

    Kodiak 1/2 ton status

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    The only time I had a problem with the trans not shifting out of first was when I replaced my carb and didn't hook up the vacum line to the trans. Hooked it up and it worked right.
     
  9. DMK

    DMK 1/2 ton status

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    Make sure your vaccum line comes off the manifold and not the carb. Check for leaks in the line. Hose should be all metal except for ends. Kick down cable is not the problem.If tork converter was not in pump all the way tranny would not get close enough to bolt to motor.
     
  10. EDdaTREE

    EDdaTREE 1/2 ton status

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    Went out today and found that it has a TV cable instead of a kickdown cable, at least thats what chilton's and hayne's manuals seem to say. Set the adjustment on it and still only have first and reverse. Vac. line to modulator should go to carb.,right? Cant get 2nd or 3rd by shifting manually,btw. Guess I'll have to dig into it over the weekend, thanx for the info guys
     
  11. EDdaTREE

    EDdaTREE 1/2 ton status

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    I hope its not what Eagle said...was working on something else and the brother-in-law had mtr. and tranny bolted together in driveway before I got to get a look at it. I'll check for vac. leals in the metal line too, hope it don't rain this wknd.
     
  12. DMK

    DMK 1/2 ton status

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    Beleive vacuum line should go to fitting on intake behind carb.
     
  13. EDdaTREE

    EDdaTREE 1/2 ton status

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    Turns out that the end of the vac. line was plugged with crud, couldnt see it cuz it points right at the trans. Thanx for the help guys.
     

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