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normal shifting??

Discussion in '1982-Present GM Diesel' started by smprider112, May 13, 2004.

  1. smprider112

    smprider112 1/2 ton status

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    I have an 85 blazer with a 6.2 pretty much all stock, Im having an odd thing with the way it shifts...not sure if this is normal for a diesel or what. Ok so when I take off normally it kinda rev's each gear pretty high, or at least it sounds like it does, 1st isnt too bad, but second, I'll be going around at like just around 35 and it will seem like it SHOULD have shifted but it wont...if I go a little faster say 40, then it will shift, or after a while maybe 10-15 seconds of this at 35 then it will finally shift. The tranny is a TH350, I just bought the truck maybe a month ago...its done this the whole time. My G/F's stepdad sold it to me so I trust him, he's had the tranny rebuilt rescently and Im pretty sure it has a shift kit cuz it shifts very solidly. Im just wondering is this normal, or maybe normal for one with a shift kit...or is it possible whoever rebuilt the tranny used a gasser torque converter or something weird. The whole thing is very livable I just wanna know if its normal is all...also what should the stock gears be? I think he said they where 4.10 but im not sure. thanks for any info.
    -Brian-
     
  2. kennyw

    kennyw N9PHW Premium Member

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    It may be possible that the vacuum modulator, vacuum line or vacuum generator may not be functioning properly? Have you pulled the vacuum line off to verify you have vacuum? Checked the condition of the vacuum line recently?
     
  3. smprider112

    smprider112 1/2 ton status

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    how do I check if I have vacuum or not??
     
  4. kennyw

    kennyw N9PHW Premium Member

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    With the truck running pull off the vacuum line and check to see if it is sucking in air /forums/images/graemlins/thumb.gif
     
  5. smprider112

    smprider112 1/2 ton status

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    hahaha...and now for the really stupid question, where is the vacuum line? unless Im blind I cant see it.
     
  6. arveetek

    arveetek 1/2 ton status

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    There should be a vacuum line running from the top of the vacuum pump located in the rear valley of the engine to the passenger side of the transmission. The vacuum modulator is a little bell-shaped thing screwed into the side, pointing out with a vacuum barb on the end of it. The TH350 was swapped in by the previous owner, it was never offered from the factory behind the 6.2L. If the guy didn't run a vacuum line to it, it will shift way too late. In fact, you might even need to have a vacuum regulator valve mounted on the injection pump to make it shift right. With full source vacuum to the tranny all the time, it may shift too soon!

    Casey
     
  7. kennyw

    kennyw N9PHW Premium Member

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    [ QUOTE ]
    hahaha...and now for the really stupid question, where is the vacuum line? unless Im blind I cant see it.

    [/ QUOTE ]

    Sounds like it was never installed when the tranny was swapped in /forums/images/graemlins/doah.gif
     
  8. smprider112

    smprider112 1/2 ton status

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    I'll have to look for it...I thought the TH350 did come with blazers for that year?? I'll have to check maybe it isnt a 350 but 400 maybe? how can I tell the diff...Im pretty sure everything is stock I dont think he did anything to it, and he was the original owner.
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    85 6.2 Blazer should have a 700R-4...unless it's a M1009 then it'll have a TH400.

    Those are the two stock possibilities. If it's anything else it has been swapped in (like my SM465...)

    Rene
     
  10. smprider112

    smprider112 1/2 ton status

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    this is really weird then...I dont think he changed the tranny but I know its not a 700, its not a military cucv so it isnt a stock 400...I wish I knew what the different tranny's looked like underneath. I'll have to ask him cuz I thought he said the tranny was rebuilt, maybe it got a new one instead, cuz I think its a TH350.
     
  11. savagek5diesel

    savagek5diesel 1/2 ton status

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    If you go to your local parts shop they should have a page of the different tranny pans for GM. they all vary a bit so if you take a good look at yours then look at all of theirs then you ought to be able to figure it out. my 6.2 has the 700r4 and 2nd gear shifts at like 45 when i'm getting on the freeway or when i'm peddle down through town.
     
  12. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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