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IT12 - 3204 piston problems

Discussion in 'Tool Carriers' started by Robbo55, Aug 25, 2019.

  1. Robbo55

    Robbo55 New Member

    Joined:
    Aug 21, 2019
    Messages:
    3
    Location:
    Western Australia
    Hi, from aus!

    Have tried searching before posting.


    3204: 45V74688

    Currently doing a major overhaul on my 3204 engine. Ive bought brand new everything and the piston pin does not fit into the bearing. The wall thickness of the new bearing is thicker than original. Looking at my parts book and confirming with the Cat dealers online system, we both have the same numbers.

    Piston pin: 7N9803
    Bearing: 9N5082

    The only difference in part numbers from the new to old, is the old bearing has an X at the end. But the dealer says it doesn’t mean anything and nothing comes up with the X.

    The pin from new and old are the same diametre. It’s the wall thickness of the bearing that has changed, so the pin will no longer go through the piston.

    This has been confirmed with measuring tools.

    I’m waiting to hear back from the Cat dealer to see what Cat have to say.

    Has anyone else come across this problem?


    Cheers, Ben!
     
  2. Cmark

    Cmark Senior Member

    Joined:
    Jan 2, 2009
    Messages:
    2,046
    Location:
    Australia
    Back in the day it was common for new small-end bushes to have to be reamed to size. Don't stress, just drop them in to whoever does your engine machining work locally.
     
    Robbo55 likes this.
  3. Dave Neubert

    Dave Neubert Senior Member

    Joined:
    Jul 19, 2018
    Messages:
    358
    Location:
    Monroe NC
    Like CMark said you have to have bushing reamed or honed to fit. Do you have the proper mandrel for pressing the bushing in because it is almost impossible to install it without damaging it
     
    Robbo55 likes this.
  4. Robbo55

    Robbo55 New Member

    Joined:
    Aug 21, 2019
    Messages:
    3
    Location:
    Western Australia
    Thanks fellas.

    Caterpillar came back with what you both said: press the bearings in, then machine to size. (They supplied me with specs)

    Nope, I don’t have the tool to press them in. I’ll leave that up to the machine shop who done my block, crank and head!
     
  5. Nige

    Nige Senior Member

    Joined:
    Jun 22, 2011
    Messages:
    11,774
    Location:
    G..G..G..Granville...........!!
    Speak to your machine shop before they start. Make sure they have to correct tooling for the job and aren't just winging it.
    An induction heater is one way of getting those bushes in easier, but it will still require a mandrel to ensure the correct bushing alignment.
     
    DB2 likes this.
  6. Robbo55

    Robbo55 New Member

    Joined:
    Aug 21, 2019
    Messages:
    3
    Location:
    Western Australia

    Yep, will do. Thanks for your information!