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3126 Cat into 645 Fiat loader?

Discussion in 'Wheel Loaders' started by Cat_man320, Mar 5, 2020.

  1. Cat_man320

    Cat_man320 Well-Known Member

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    Hi folks
    Well I just bought another old 645 Fiat wheel loader. I acquired a real good 3126 Cat engine but it's computerized , Engine is from a school bus and I got the whole bus so I have all the wiring harness . My question is : does anybody know what wires or numbers on the ECM I would have to use to get the engine running and to use the potentiometer(accelerator) to make the loader usable . I know it needs a ground . and hot wire plus a hot wire when the key is on and the accelerator . I think it is a 50 pin ECM . I see these engine on sale on E bay and other places and they have the engine on a test stand with about 5 or 6 wires going to the ECM . Anybody know which ones I should use . ?
    Also looking for a bell housing and flywheel the engine I got has a SAE #2 and I need a SAE #3 or 16.125 dia on the inside circle .
     
  2. Delmer

    Delmer Senior Member

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    I don't always do stupid **** like this, but when I do, I leave the engine running and take apart the wiring harness and remove any wires that don't look important, check that your accelerator still works after every snip and you won't have to fix much if you cut the wrong wire.
     
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  3. Mark250

    Mark250 Senior Member

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    serial number will get you an electrical schematic
    you may need a pwm pedal for throttle control
     
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  4. Cat_man320

    Cat_man320 Well-Known Member

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    Thanks for the replies guys . Delmer, I have done lots of stupid **** over my 55 years of wrenching on heavy equipment. If i could afford to install a new engine in the loader , I would probably do so, but I have very little faith in those 3500 MKII engines. Now I realize that the 3126 might no be the best engine out there either but for what I paid for it , it's worth a try . The bus is running and I haven't chopped any wires, i just thought somebody might know the pin configuration for the 5 or 6 wires that I need to hook up rather than spend time trying to get the underdash harness out and still have a running engine.
    Mark , I have the whole running bus and I have the pedal .
     
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  5. kshansen

    kshansen Senior Member

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    First off I know nothing about this engine but knowing nothing seldom stops me from making comments!

    If you can post some Cat numbers off any of the Cat components there might be a chance someone could find so info on wiring.

    Main thing might be the Serial Number of the engine, that should get to a wiring diagram of the engine on SIS.

    "Start a Conversation" with me and I could email you a copy of that !
     
    Last edited: Mar 6, 2020
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  6. Cat_man320

    Cat_man320 Well-Known Member

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    the 3126 is a BDZ 01747
     
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  7. Nige

    Nige Senior Member

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    That's listed in the system as a generator set engine............. 209 BHP @ 1800 RPM.
    That doesn't sound much like a bus engine to me.
     
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  8. Cat_man320

    Cat_man320 Well-Known Member

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    Thank you for the info but I have no idea . it is in an older school bus and could have very well been changed years ago .
     
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  9. Nige

    Nige Senior Member

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    Here is what appears to be a generic electrical schematic for a 3126B Truck Engine.

    The only hope I can hold out is that when whoever repurposes the engine for truck application made the changes, that they changed everything that needed to be done to suit the application. Otherwise you have a b**stard step-child that you'll never be able to find parts for when using the Serial Number on the plate.

    My fear is that either they would have simply replaced the ECM with one from a truck engine, or even re-flashed the original ECM with some version of truck engine software. To find out what's in there will need Cat ET.

    Whether they replaced any appropriate hard parts such as injectors, turbo, etc, etc - your guess is as good as mine.

    upload_2020-4-22_18-56-0.png
     

    Attached Files:

    Last edited: Apr 22, 2020
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  10. Cat_man320

    Cat_man320 Well-Known Member

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    Thanks again for your information . from looking at the schematic , it looks like I should be able to start this engine and have an accelerator pedal with about 6 or 7 wires plugged into the ECM
     
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  11. Nige

    Nige Senior Member

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    Is the engine still installed in the bus chassis..?
    If so, then why not try following the wiring from the engine ECM as it is installed right now and see where each wire leads.?
     
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  12. Cat_man320

    Cat_man320 Well-Known Member

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    I'll have to do that just to make sure , so many wires in the harness under the dash , gonna be a pain to try a get that harness intact . This engine is 209 hp @1800 so it's about 50 hp more than I need but I need more rpm then that to stall the torque . I need at least 2500 rpm . just hope the engine is not ecm'ed at 1800 , then again it worked in the old automatic bus . Thanks again. before i make the plunge , I will check with the cat dealer and see what info if any they can help me with . I still have to find a SAE #3 bell and flywheel for this engine and low profile base pan . Thank you again for your help .
     
  13. Nige

    Nige Senior Member

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    A couple of comments.
    1. The engine WAS at one time rated at 209 BHP @ 1800 RPM when it was built by Cat to run a genset. What it is rated at right now, either BHP or RPM-wise, is anybody's guess.

    2. The Cat dealer is not likely to be any help to you because all they are going to be able to go on is the Serial Number which leads to all the data I've already posted. The only help I can see the dealer (or anyone else who has ET) being is the ability to hook up to the engine and take a look at what Flash File Part Number is in the ECM. That Part Number will determine what the engine rating is SUPPOSED TO BE right now, PROVIDED that someone not only changed the electronic Flash File but also made the appropriate iron changes to support the engine re-rating that I referred to earlier.

    3. If the dealer (or indepenndent mechanic) has the appropriate test harness they MIGHT be able to have a look in the ECM if you were to take it to them, which would save the expense of a field service call.
     
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  14. crane operator

    crane operator Senior Member

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    Find someone who rebuilds and dyno's engines before sending them out the door. They will know which wires they hook up on the test stand and you will eliminate a lot of headaches.

    Of course if you really wanted to eliminate headaches, you would just use a 6bt, 8.3, dt466, cat 3306, perkins, deere or anything with a mechanical injection pump and air compressor. Whatever fits in the engine bay. The 3126 isn't known for being a great engine. But I'm kinda biased because I'm not the best electrical mechanic, but I can make linkages and hook up a 12v fuel solenoid, without needing CAT ET computer hook ups.

    I realize the 3126 is already there, but I would find something easier to make work.
     
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  15. Birken Vogt

    Birken Vogt Charter Member

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    I am also wondering what the operating characteristics will be like in a loader when the throttle type is set up for a bus.
     
  16. crane operator

    crane operator Senior Member

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    I think the only real issues with engines and governors comes from trying to use genset engines in equipment or trucks.

    I've used engines from combines and trucks in cranes, without any problems. Throttle input is throttle input and usually it works out. But I'm a primitive pete on things like that.

    I don't think you would notice any difference in a bus engine into a loader. Maybe bump the idle up a little so the hydraulic pumps wouldn't kill it down low.
     
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  17. Mark250

    Mark250 Senior Member

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    here are the ECM pin numbers that will get your engine running
    Un switched power directly from battery via 20A circuit breakers per line
    pin # 48, #52 and #53
    Bat Neg return from ECM pin #61, #63 and #65
    Bat power via key switch to ECM pin#70
    wire gauge needs to be at least 14G
    you have mentioned that you already have the throttle so I wont go into that
    Even if you run this engine I have no way of knowing if the ECM will derate from missing parameters this is controlled by the Flash file installed in the ECM which we have no access to
    if you could get a config file download and a status report we could offer more help
     
  18. partsandservice

    partsandservice Senior Member

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    I have heard people but down the 3126 but can't understand why. I have no experience with the truck version. On the industrial side I find the 3126 mechanical , the 3126b and c and the c7 to robust and dependable. I have a cat 3kz skidder with 17k hours original engine 3126 mechanical. It has the fuel rack like a 3116 .
     
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  19. Birken Vogt

    Birken Vogt Charter Member

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    Around here they were thought of as high-revving, not torquey, not powerful, and they tended to drop valves and shell HEUI pumps. Maybe the hills did them in here, you are either grinding uphill WOT or downhill at redline with the engine brake on here all the time.
     
  20. partsandservice

    partsandservice Senior Member

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    So max rpm would be 2200 in the applications I am familiar with . Some applications such as a rubber tired buncher operate full out constantly. And what a beast that machine is with a 3126b stuffed in it. Skidders and wheel loaders will have a foot feed and would throttle like the bus. I think it would work correctly in that loader if you could put a flash file from a wheel loader with that same teir level 3126b engine. Engine parameters would then be talered to the application. I might be repeating some above. You may be able to buy a Murphy display that that you could hook into the data cable and then not have to run all the manual gauges. The Bus engine likely used J1939.