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Technical A real trans head scratcher

Discussion in 'Traditional Hot Rods' started by Acelogik, Nov 21, 2017.

  1. Acelogik
    Joined: Jul 2, 2012
    Posts: 3

    from Hainesport


    I have a weird issue and maybe someone could help me out. I'm running a TH350 with a 3000 stall converter. If I start my van and put it into any gear I get nothing... until I shut it off and start it up. Than it goes into gear like it was its job. Shifts great and fluid levels are good according to dipstick (I hope anyway... deep pan with plastic lokar dipstick). Any ideas would be greatly appreciated.

    Seems to have started this since the temps have gone below 50*
  2. Put another quart in it and try it then.
    Yes, I know, it's not good to be over full, but just do it as an experiment.
    olscrounger likes this.
  3. Converter draining back???
  4. Acelogik
    Joined: Jul 2, 2012
    Posts: 3

    from Hainesport

    Another quart is not a bad idea. I'll give it a whirl. It shows overfull when off and perfect at idle hot but that's not to say the dip stick isn't off.

    This problem didn't start right after I swapped the converter and the deep pan BUT has happened SINCE I have. Been running strong for about 3 months since swap with no issues. Almost seems to be temperature related but I'm no trans expert

    I have also heard about this converter draining back as well. Never had that on any other vehicle but stranger things have happened.

  5. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 5,346


    If the converter is draining back, another quart won't make any difference. Does this just happen after you haven't driven it for a while (overnight)? Have you just let it idle for a couple minutes and then tried to put it in gear?

    The converter should refill within several seconds if it is draining back.
  6. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 25,733

    Jalopy Joker

    why running that converter? is it new? how many miles on it? how does fluid look/smell?
  7. Right. They all drain back to half full after a period of time.
    If you're lucky, the filter gasket is on upside down/ backwards/ missed a bolt.
    Probably not gonna be that lucky though.
  8. Sheep Dip
    Joined: Dec 29, 2010
    Posts: 1,572

    Sheep Dip
    from Central Ca

    Without more info on the van power plant, I'm imagining a daily driver, that's a lot of stall and would generate a lot of heat. Heat and auto trans are bad.
  9. mgtstumpy
    Joined: Jul 20, 2006
    Posts: 8,463


    Deep pan, OEM shallow pickup might be the cause?
  10. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,793


    My thoughts, too. 3,000 rpm stall in a van, is a bit much.
  11. Depends on how you go about it.
    Could be a tight 9.5 (245 mm) which would drive fine at light throttle, flat ground.
    Or, could be just a 12" "heater" , and yes, 3000 would not be good.
  12. Acelogik
    Joined: Jul 2, 2012
    Posts: 3

    from Hainesport

    Ok. Background on van. 3400 lbs with me in it. 12 bolt 3.73:1 spool. 5.3 vortec with Holley efi managing it. Those ls motors like a bit of stall (2500) and my next project is a cam which is right in the 2800-3200 range. Van is solid high 12’s right now And I plan on getting it into 11’s by next year. It is a 10” converter.

    Trans pan came with extended pickup tube do it shouldn’t be that. As far as filter gasket upside down or a missing bolt, I will definitely check that during winter. Was even thinking about sending the trans for a rebuild just to ease my head.

    The converter has about 300-400 miles on it and the fluid looks/smells good. I do have a remote mount trans cooler with a fan on it underneath the van. Tstat is at 180* and it barely runs. I will get a gauge on the in side to check temps.
  13. mt shasta steve
    Joined: Mar 26, 2010
    Posts: 270

    mt shasta steve

    A buddy of mine ran a transmission shop for years. He recommended with my hotrods (since they sit for several months over the winter) to start the engine, put the trans in neutral for about 30 seconds. This fills the torque converter. Then drop in gear and go.
  14. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 571

    from 94577

    I actually do this with all my AT cars. Especially the higher mileage vehicles, where they drain down much easier, this seems to really help the initial cold response. Most ATs this technique seems to charge all the circuits(not pressurize/activate) and removes the two times going into gear feel when placing in Drive.

    Ideally you should get an oil pressure gauge(0-300PSI) and monitor your main line pressure.

    It could be a sticking oil pressure relief valve, or possibly the sprag clutch is going bad, but I would drop the pan first and make sure there isn't something goofy going on with the sump pickup filter or O-ring.

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