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TH350 w/ 1st and R only

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Blazer_Boy, Mar 16, 2001.

  1. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Alright, I've got a hankering to get our lawn ornament operational again. Its a 1981 K5 Silverado with a '78 350 and TH350 Tranny. This was pretty much my moms truck so I never did any mantiance. I wasn't even old enough to drive back when she was using it, lol. I finally got my license after junior year and it changed hands to me. I started to learn with it and go crazy fixing stuff. I pull the dipstick on the tranny about a day after it "became mine", it was bone dry..CRAP! I filled it up and kept it at the mark all the time. Well about a month later it stopped shifting. All it has is first gear and reverse. I also checked out the ratio on the diff, 2.73 and its running 32" (She didn't know about this back when she bought the 32"s about 5 years ago). I've got two theories going here now. A) The governor needs a look at (needs some clues how to check this out). B)The thing is pretty much cooked and its time for another one. I'm inclined to go with B. Would it be wise to pull the pan and have a look at whats floating in the bottom. I've got a TH350 in '76 C10 that I might just put in then if the '81s is cooked. I should only have to change tailshafts, correct?
     
  2. baldbandit

    baldbandit 1/2 ton status

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    i would check the governor gear and then change tranny filter and fluid! If that doesn't work, it is time for a rebuild or a new tranny.

    baldbandit

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  3. wheelin247

    wheelin247 1/2 ton status

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    try your vacum as well i had the same problem and all it was was a little vacum hose that needed to be changes .....good luck
     
  4. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    You'll have to forgive because I've never had trouble with transmission before so my knowledge is next to nill. Where abouts does the vacuum line come off the carb? How you do I check the governor. She's really greasy and all I found was one bolt on the front of the governor.
     
  5. Thunder

    Thunder 3/4 ton status

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    Yeah it sounds like it may be your vacume modulator. The vacume modulator uses manifold vacume to tell the trans when to shift. It looks like a small can screwed in the back of the trans above the pan. It should have a vacume line going into it. If the line is off or cracked or the modulator is bad the trans wont shift out of first. Put a new one in They are cheap to replace.
     
  6. mudfanatic

    mudfanatic 1/2 ton status

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    thunder and wheelin are probably right on, the vacuum line will originate from behind the carb and in front of the distributor. If your rig has cruise it will be a 3 way nipple screwed into the intake manifold. one line will run to a plastic canister on the passanger side of the rig, the other side will go to the cruise, if you have cruise, the one out the top will connect to a metal line that dropps to the back of the tranny. If the rig has been sitting that long i would change all of the lines $10 tops, and the modulator on the tranny that the line connects to (I have no idea what those run but I wouldn't guess more than $15-20.
    good luck
    Dan

    <font color=red>get involved with land issues or lose the land</font color=red>
     

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