Th350 acting weird at WOT

Discussion in 'Troubleshooting & Diagnosis' started by Justin79maro, Aug 3, 2017.

  1. Justin79maro

    Justin79maro Member

    88
    1
    Jan 15, 2015
    Bonne terre, missouri
    My trans was rebuilt a year ago and has 6500 miles on it, it has a hardened sprag, new clutches and a shift kit. Also has a 3,000 stall. When I go WOT mostly going about 20mph and from a stop when it get to roughly 80-90 when it's suppose to shift into 3rd it feels like it revs out but it makes no power and it doesn't keep pulling hard like it should when I punch it from say 60mph. It just hangs at about 5000-5500 and it just stays there and feels like its barley pulling and the engine acts a little funny like it's just floating (sorta live valve float). Could my pump be going out or my clutches be bad?
    Btw: my engine makes 440hp/450tq. Any input would be helpful!
     
  2. wnmech

    wnmech Veteran Member

    681
    27
    Jul 20, 2014
    grand prairie tx.
    Possibly timing?
     
  3. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

    8,807
    131
    Nov 4, 2004
    Ringgold, GA
    Doesn't really sound to me like a transmission problem. What's leading you to that conclusion?
     
  4. Justin79maro

    Justin79maro Member

    88
    1
    Jan 15, 2015
    Bonne terre, missouri
    It's doing it before it shifts and sorta feels like a trans problem. What do you think it sounds like
     
  5. Justin79maro

    Justin79maro Member

    88
    1
    Jan 15, 2015
    Bonne terre, missouri
    It's at about 14 degrees when at idle
     
  6. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

    8,807
    131
    Nov 4, 2004
    Ringgold, GA
    Only doing it just before it shifts into 3rd at WOT ~ 6K + rpm? Since it's a TH350, disconnect the passing gear cable at the carburetor. It doesn't control pressure like a 700R4, so it won't cause any problems, just eliminates passing gear. See if that makes any difference. Also, check the vacuum modulator on the back of the transmission with a hand type vacuum pump.
     
  7. Justin79maro

    Justin79maro Member

    88
    1
    Jan 15, 2015
    Bonne terre, missouri
    6000rpm is what it shifts at. You think it could be line pressure? Only causing it to do it when I floor it from a stop or around 20mph and run it on up to 3rd? This has had me stumped for a while now and it only does it every once in a while but today it did it 3 out of 3 from a dig/ 20 punch
     
  8. CorkyE

    CorkyE Veteran Member Lifetime Gold Member

    8,807
    131
    Nov 4, 2004
    Ringgold, GA
    I'm not convinced it's a transmission issue but do the couple steps suggested first. I'm not a transmission guy but usually when a pump goes out, it out. And if it were line pressure, you should notice it on 1 - 2 shift. I would more lean toward fuel delivery issues.
     
  9. APEowner

    APEowner Veteran Member

    636
    10
    Dec 9, 2013
    Albuquerque, NM
    It pulls hard to 6k RPM in 1st?
     
  10. Coadster32

    Coadster32 Veteran Member Lifetime Gold Member

    1,185
    41
    Oct 2, 2013
    Milford,CT
    Maybe hold the rpms high in another gear and see if it still does it. Might be a fuel delivery issue that doesn't show it's head till the carbs get drained a bit.
     

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