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Anyone ever hear a Th350 torque converter (or pump?) "sing"?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BadDog, Jan 19, 2004.

  1. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Anyone ever hear a Th350 torque converter (or pump?) \"sing\"?

    Beginning of the last trip out (Thumper's visit) my truggy started making a sound I've never heard from a vehicle before. Sounded sort of like a bird whistle in the area of the torque converter or trans pump. Mainly at idle or just above, then it would go away only to come back next time I dropped to idle. It seemed to be occurring at a frequency of about 1 per revolution just from looking at the converter spinning as I heard the noise. I had plenty of fluid, slightly over full in fact. I added additional fluid just because I noticed it “loosing prime” off camber and the chirp went away for about 15 seconds or so, then returned. /forums/images/graemlins/confused.gif. It’s now roughly 1 qt over full (any more and it would start puking) and still doing the same thing.

    Specs:
    Standard Th350 with (apparently) mild build and shift kit (bought used so I don’t know the specifics, works well till now though). Roughly 12-1600 rpm stall converter. Large stacked plate cooler and +3 pan with deep pickup. That’s about it...

    Any ideas?
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Re: Anyone ever hear a Th350 torque converter (or pump?) \"sing\"?

    Oh, and one more thing. When you cut it off, the whistle tapers off over a second or so. I'm guessing that's pressure bleading off, maybe indicating something stuck in a passage?
     
  3. NITRO

    NITRO 1/2 ton status

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    Re: Anyone ever hear a Th350 torque converter (or pump?) \"sing\"?

    sounds like maybe a vacum leak in the line going to the modulator on the trans.

    NITRO
     
  4. shane74

    shane74 1/2 ton status

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    Re: Anyone ever hear a Th350 torque converter (or pump?) \"sing\"?

    I have never heard of this before. I know, I am absolutely NO help to you. Sorry. Please keep us posted on what you find out though! /forums/images/graemlins/smile.gif
     
  5. Mudzer

    Mudzer 1/2 ton status Author

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    Re: Anyone ever hear a Th350 torque converter (or pump?) \"sing\"?

    Russ,

    I had a TH350 that the outer drive of the pump locked up and the whining noise was the sound of the Splines being ground off the pump shaft. It would still pull the truck but did not have the torque multiplication needed to overcome offroad situatoins.

    Mine sounded like a blower whine - I thought it was cool till I realised what it was!

    Sounds like a similar thing has happened. The "purge" you explain could be the loss of the converter. Meaning, when you shear off the splines on the pump shaft, it no longer turns the inner vanes of the converter fast enough. Eventually it would have left me stranded I believe.

    Of course, not being there to listen and ultimately pull the tranny loose, I can't be sure! Good luck.
     
  6. BobK

    BobK 1/2 ton status

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    Re: Anyone ever hear a Th350 torque converter (or pump?) \"sing\"?

    Mine does an awesome rendition of "The Rose" by Bett Midler. /forums/images/graemlins/rotfl.gif

    Sorry for the smart #ss reply. /forums/images/graemlins/grin.gif
     
  7. 75-K5

    75-K5 3/4 ton status

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    Re: Anyone ever hear a Th350 torque converter (or pump?) \"sing\"?

    Mine does some kind of funky chirping noise every once in a while. It's done it since I bought the truck and I've put about 5,000 miles on it so far, but then again I'm not one to fix things until long after they've broken. /forums/images/graemlins/rotfl.gif
     

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