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BIG problem

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 4wood, Nov 3, 2003.

  1. 4wood

    4wood 1/2 ton status

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    I drove my auto '85 K5 about 140 miles from home to school a few weekends ago and as I got off of the interstate I noticed that the engine was revving up really high and not kicking into 2nd and 3rd gears when it should. I checked the atf and it was low, so I topped it off and that fixed the problem for the time being. This weekend, I went on a camping trip with some friends and had the same problem, despite correct fluid levels, and it seemed worse than before. I don't have a tachometer, but it sounds like it's revving to about 4000 or 4500 rpm before shifting? When we returned from the mountains, she just shut off almost right after I got off of the interstate; however, the radio did not turn off and I was immediately able to restart her. I don't driver her much since I'm in school, but this has me rather perplexed/worried. Anyone have any ideas on this one? To the best of my knowledge the trans is a TH700-R4. Thanks!
     
  2. ramjet gmc

    ramjet gmc CK5 Staff Staff Member Moderator GMOTM Winner

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    the trans is a TH700-R4


    time for a new trany -- but what is the milage on your truck? and have you dun any thing that may have changed the TV cable --like a new carb ect
     
  3. k5guyva

    k5guyva 1/2 ton status

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    Just a guess, but I think one of the bands are going out. The 2-4 band would be my gut reaction. If you have a lot of miles on it, then it's rebuild time.

    If you plan on keeping the truck and rebuilding it, take a look at the TransGo kit.

    TransGo Link

    They are supposed to greatly decrease the wear and heat on your tranny.
     
  4. Thunder

    Thunder 3/4 ton status

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    Just courious. The truck is an 85 right?
    Are you sure you have a 700r4 in it? You only mention 1st, 2nd, and third gears. There are 4 gears(overdrive) in a 700.

    TH 350 and 400 trannys have 3 gears.
    Check to be sure if the trans is a TH400 or TH350. If it is a TH350/400 Your problem sounds like a bad vacume modulator or disconnected/broken vacume line to the modulator. Very cheap and easy to fix.

    If you do have a 700r4 check the TV cable to make sure its connected to the throttle linkage and adjusted properly.
     
  5. 4wood

    4wood 1/2 ton status

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    The odometer reading is off since I have 33s. It reads 145k, but I'd say more along the lines of 137k. Also, it's TBI, so there is no carb. Yeah...I was hoping I wouldn't have to do a rebuild...
     
  6. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    with 33's your mileage is actually gonna be lower than what it would have been so 145 more along the lines of 153
     
  7. 87BrnRsd

    87BrnRsd 1/2 ton status

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    Even though its TBI, it stll has a tv cable. Go here: TV CABLE ADJUSTMENT to see exactly how to adjust it. You may also want to check the transmission governer gear (shift modulator.) There will be a round metal cap towards the top of the tranny on the drivers side. Pry the cap off with a screwdriver, and pull out the governer. If the plastic gear on the end of it is all stripped and rounded off, then that is your problem. If not, than just slide it back in. The modulator only cost me like $25 when I had to get one last month. No biggie.
    -Harrison
     

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