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? for auto tranny techs

Discussion in 'The Garage' started by Russ, Mar 8, 2006.

  1. Russ

    Russ 1/2 ton status

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    I have a th400 in my 88 crewcab dually. After I swapped the 350 engine out for the 454 I noticed the tranny did not shift nearly as firm as it did before. I am also getting a knocking? noise out of what appears to be the front of the tranny when I frst start it up. It will subside after about 45 seconds. I disconnected the torque converter and verified the noise is not coming from the engine.

    My question is: Is there anything in the tranny that can make a knocking noise???

    I left the torque converter on the tranny when I swapped the engines. My 454 does have an aftermarket eagle crank in it and the torque converter does not seem to slide all the way out to the flexplate. It stops about a 1/16" short. I shimmed the difference with flat washers between the torque converter and flexplate. The tranny has about 2300 miles on it since it was rebuilt and the torque converter/ cooling lines/ radiator and tranny cooler were all new at that time. I appreciate any help,

    Russ
     
  2. Russ

    Russ 1/2 ton status

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    help!
     
  3. TrcksR4ME

    TrcksR4ME 1/2 ton status

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    Is it hitting the flexplate in some way not allowing it to slide up to it flush? You should not have to shim it and there is no reason that the torque converter would not slide out far enough unless it his hitting something.
     
  4. Russ

    Russ 1/2 ton status

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    Best I can tell the torque converter is bottoming out against the end of the crankshaft. It is only about 1/16th, but it is making the noise regardless of when I shimmed it and without. If I don't put the washers in there it appears to bend the flexplate in just a little to meet the torque converter when I tighten the bolts down.

    I have watched everything spin with the engine running and there is not anything externally that is making contact.
    Thanks,

    Russ
     
  5. tarussell

    tarussell 1/2 ton status

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    Russ - what's up ?
    Hollar at me before You head up to Tenn. and we will break bread together at the Cracker Barrell in Crestview and talk truck talk !

    Is your crank play allowing the converter to walk back and slowly kill the tranny pump ? Is there any increase in whine or just the knocking sound ?

    Tom
     
  6. Russ

    Russ 1/2 ton status

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    Tom,
    I will be in and out of Florida until the kids finish up the school year so we will definitely get together before I leave. Today was my last day in the Navy though. Feels kind of strange after almost 25 years.

    I have about 1/4" of back and forth play with the torque converter unbolted from the flexplate. That is a little less than I had with the 350 engine, so I am thinking that the torque converter may be pushed back too far into the pump. Will the pump make a knocking noise? The noise never really turns into a whine, but does come and go with the temperature of the tranny. I am definitely getting a more sluggish shift than I had before also.
    Thanks,

    Russ
     
  7. tarussell

    tarussell 1/2 ton status

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    My knowledge is limited on auto tranny's but I do believe your TH400 is slowly dying. I have seen this problem before and it has turned out to be the pump getting beat to death internally and that is what causes the pressure variance/ sluggish shifts.
    Have you dropped the pan and checked for the pretty shinny stuff in the filter ?

    Tom

    P.S. CONGRATS on the retirement ! Uncle Sam lost a hell of a resource today ........
     
  8. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    Check to make sure the flexplate isn't cracked...
     
  9. Russ

    Russ 1/2 ton status

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    I dropped the pan once a couple of weeks ago and had what appeared to be some brown (clutch?) material and some fine metal, but not very much. I am going to drop it this weekend and check it again. I have a bad feeling you are right though and my tranny pump is going.

    Russ
     
  10. Russ

    Russ 1/2 ton status

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    I did check the flexplate and it looks good, It is a brand new one that I put on with the engine swap and only has about 150 miles on it now.
    Thanks,

    Russ
     
  11. tarussell

    tarussell 1/2 ton status

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    The hard part is finding out "why" the pump is going at this point . Before you pull it it might be wise to get ahold of someone that actually knows what they are talking about in depth. I would hate to see a new pump go south due to the same problem. I truly belive that the pump is going out but the crank walk is just a guess as to why.....

    Keep Me posted !
    Tom
     
  12. diesel4me

    diesel4me 1 ton status Premium Member

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    .....hope its not this...

    I saw quite a few motor homes and 1 ton trucks with the 454/TH400 combo have problems with the thrust bearing on the cranks getting wiped out due to torque converter "balloning",back in the late 80's ..it actually swells up, and puts excessive end thrust on the crank under heavy loads while pulling..they had some service bulletins posted on this in some trade journals I read at the auto parts store and machine shop I worked at..they claimed a kinked cooler line or clogged cooler could lead to converter balloning,and cause both the tranny and engine to fail...:doah: ...
     

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