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Tranny not shifting???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Shooter40, Dec 23, 2000.

  1. Shooter40

    Shooter40 Registered Member

    Joined:
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    Location:
    Oklahoma
    Howdy gents, need some input on a new problem, I was deployed for about 5 weeks and my 81 sat in the drive way while it turned cold and froze and snowed here in Okie City, I returned monday and after replacing a froze battery, started her up and went for a drive and discovered the tranny wouldn't shift from first to second, it goes directly from 1st to 3rd, and when I stop a a light it forgets to downshift to first it stays in high or 3rd, now very occasionally it will shift properly, or if I shift with the shifter it functions great, nice firm shifts.......now second problem, it locks up and releases the lockup converter when I'm cruising around 35 to 40 mph. this isn't a big deal it just didn't used to do it as much as it does now, I'm at a loss on the shifting thing though, any advice on what it might be and how to remedy it would be appreciated, the tranny is fairly new I put it in in May. haven't had any probs till now
     
  2. Blue85

    Blue85 Troll Premium Member

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    Location:
    Grand Rapids area
    Since the tranny can be shifted manually, there is nothing wrong with your clutches, so whatever the problem is, it is unlikely that the transmission will have to be removed from the truck to solve the problem.

    If my hunch is right, you're in luck. The problem may be as simple as a misadjusted TV cable. When you say "high or 3rd" I assume that you have an OD tranny and I believe that '81 was the first year for the TH-700. Some moisture may have frozen around your throttle or TV linkage and knocked it out of adjustment, possible when you first pressed the throttle. If the TV is way off, the tranny will operate as though the engine is always at idle. That way, it just skips second and drops into 3rd based on the vehicle speed. To adjust the TV, there is a little button on the top of the cable that connects to the throttle linkage on the carb. You push the button in and slide the little slider all the way back towards the firewall. Then you floor the gas pedal once before you start the engine and it self-adjusts. If yours is different than that, you'll have to pull out the manual.

    If you have a TH 350, then it could be a similar problem with the vacuum control line.

    If the Throttle Valve cable is not the problem, my next guess would be the governor, which pulls out from the side of the tranny, near the rear. It have worn through it's drive gear or have sticking weights or something. The job of the governor is to adjust the upshift/downshift fluid pressure based on the speed of the vehicle (it is driven from the transmission output shaft).

    If none of this is right, the valve body will probably have to be pulled out from the bottom of the tranny and serviced.

    "If it aint broke...Make it work better!"
     
  3. NYC K5

    NYC K5 1/2 ton status

    Joined:
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    Location:
    Staten Island NY/da bronx
    i dont know much about automatics but always check the simplist thing first, like your fluid level. also like blue 85 said your linkage may need to be adjusted
     

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