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Cat 931B cummins engine swap

Discussion in 'Track Loaders' started by magnagreg, Feb 14, 2020.

  1. magnagreg

    magnagreg New Member

    Joined:
    Sep 11, 2019
    Messages:
    1
    Location:
    central virginia
    Bought a Cat loader with a hole thru the block... did a little research on block/engine availability before hand. Price wise, it would be pointless to spend the amount the dozer is worth trying to replace with a OE cat 3204.. I HAVE purchased a 4BT and will need some machining on the bell housing, flywheel, and crank adapter to make it work with 3F/3R transmission. ANY Recommendations? any body know how the youtube guy "labrador iron" is to work with or how I might get in touch with him? He posted several videos on machine work involved .. he did have a video posted of tractor running afterwards but didnt go anyfurther on "follow up" year later videos..
     
  2. Joe Fick

    Joe Fick Well-Known Member

    Joined:
    Jul 27, 2017
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    Location:
    65459
    Wouldn't it be better if you bought an engine from a salvage yard. Cat and Cummins are 2 very different engines. Yes it can be done but the results may not be worth it. I'm guessing the 4bt Cummins is a smaller moter than the 3204
     
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  3. Fat Dan

    Fat Dan Well-Known Member

    Joined:
    Jan 14, 2020
    Messages:
    80
    Location:
    Alaska
    I'm with Joe on this one even if they have equal hp. I put a ford engine in an International for a friend it worked but not like it did in my mind. The parts I had to manufacture was a daunting experience I wish never to encounter any time soon. :mad: The the gearing between the trans and ring n pinion were not very compatible. It seemed to me there were thousands of tiny little problems that would pop up and take many hours to cobble together. So if your time working the vehicle is worth it by all means slap er together but if your time is worth anything add that to the total price tag. I think you would come out ahead of the game, both in time and money, if you put in an engine that is comparable.
    Either way good luck.
    Fat Dan
     
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  4. Welder Dave

    Welder Dave Senior Member

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    Oct 12, 2014
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    Location:
    Canada
    I'm curious how you would drive the hyd. pump since it runs off the timing gears.
     
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  5. Fat Dan

    Fat Dan Well-Known Member

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    Location:
    Alaska
    He may have realized his project was too daunting.
     
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  6. kshansen

    kshansen Senior Member

    Joined:
    Mar 11, 2012
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    Occupation:
    Retired Mechanic in Stone Quarry
    Location:
    Central New York, USA
    Thing I see with these kind of projects is that if you have the tooling and skills to do all the machining and fabricating yourself you might end up with a working machine at a reasonable cost.

    But if you have to pay a machinist to make adapters and they also have to design the adapter the cost will spiral out of control in no time. Just modifying the coolant lines could cost a pretty penny. Also does the engine have coolers that can adequately handle the needs of the 931B? Is the 4BT engine oil system configured to handle the demads of this 931B, I mean the conditions a 931B may be used under might be very different than the 4BT was built to be used.

    Basic things like is the flywheel housing of the Cummins designed for a "wet flywheel"? Are both engines running the same SAE size flywheel housings? Just looking at the displacement of the two 3204 5.2 liters and 4BT 3.9 liters has me wondering if the 4BT would have the torque output needed, could not find those spec's real easy online but still have to wonder.
     
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  7. DB2

    DB2 Senior Member

    Joined:
    Jan 4, 2015
    Messages:
    453
    Location:
    Winnipeg MB Canada
    We had 4BT’s that had a hydraulic pump drive under the injection pump. The OEM ran a big Cessna style gear pump and a smaller back to back steering pump. I still have at least one. I’ll take a picture if anyone wants to see.
     
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  8. charles walton

    charles walton Well-Known Member

    Joined:
    Nov 25, 2012
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    Location:
    Etowah Tennessee
    I think that even if he makes it work it will be VERY underpowered.
     
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  9. Tyler d4c

    Tyler d4c Well-Known Member

    Joined:
    Mar 3, 2016
    Messages:
    247
    Location:
    Salix Pa
    There's a 931 with good engine for sale cheap he needs it it's in Gettysburg pa
     
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