Cummins CM871 in-frame DYNO after?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by SophiaWYO, Apr 22, 2021.

  1. SophiaWYO

    SophiaWYO Bobtail Member

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    Hello, I'm in the process of getting my Cummins ISX CM871 engine overhauled. Some tell me to get the truck to a dyno and have them break it in. Some have told me, just run it. The closest dyno is 255 miles away from me, so I'm going to have to drive it at least that far even if I get it dyno'd.

    I live in an area where my closest loads are 4 to 5 hours away. I want to make sure I seat everything correctly since I'm spending close to 30k on this rebuild.

    Any advice would be greatly appreciated..

    Sophia
    O/O from the Cowboy state
     
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  3. Magoo1968

    Magoo1968 Light Load Member

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    A buddy is getting his inframed too right now if the parts ever show up (COVID delays) he was told to substitute one gallon of oil for gear oil due to zinc being removed in oil .
     
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  4. AModelCat

    AModelCat Road Train Member

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    Honestly I'd just run it.

    By the time you get to the dyno things will mostly be seated in anyways.

    Minimal idle and put a load on it as soon as you can.
     
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  5. BoxCarKidd

    BoxCarKidd Road Train Member

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    That is interesting. I used to run Rotella 15 w 40 in everything but my chainsaw. Then I read about removal of zinc and such. Supposed to be good for the diesel exhaust emission systems but not for flat tappet cams? Have been wondering what to do myself.
     
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  6. Flint1

    Flint1 Medium Load Member

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    There is no flat tappets in an isx. Zinc is a non issue. Just fill with good quality oil and run it. I never understood adding gear oil to engine oil. Most gear oil is GL5 rated and is no good for bronze bushings.

    Like @AModelCat said. Run it. Most engine manufacturers suggest varying your speed often.

    Drastically shorten your next oil change interval. Good opportunity to clear any dust and crap out of it. Cut open the filters to make sure nothing is piling up in it.
     
    Last edited: Apr 22, 2021
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  7. lester

    lester Road Train Member

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    Think about every new truck that's ever been built. How many of them were ever put on a dyno or ran hard the first thousand miles? Probably not very many.

    John Deere sells break-in oil. Some guys use it in trucks. We always did with new tractors. Usually 2 or 3 changes after 100 or so hours each
     
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  8. BoxCarKidd

    BoxCarKidd Road Train Member

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    To my understanding and the best of my knowledge The piston rings need to be under load to seat them to the cylinders early on. If you put an engine together and let it idle for 4 hours it can cause the cylinders to glaze. This may cause oil consumption and blow by forever.
    I toured the JD plant in Germany. When those tractors come off the line they go right on a dyno. Rollers on the floor, test HP and such. Not for long. If everything is good it goes left to the shipping department. If something was off it went right to the correction department. That is all the load they had maybe two minutes.
    When you by a new vehicle how do you drive it?
    Just put it right to work. Don't let it sit and idle. If you cannot load it go to the nearest steepest hill you have. High gear and pedal to the floor. Left foot on the brake and slowly bring it to its knees. Let the brakes cool off and repeat that a time or two. I thank you are good just do not sit and idle.
    Anyone else ever heard of one of the big three with and oil burning issue in the 50's? The hone deal on the cylinders was not correct and the rings would never seat. Dealer fix was to run the engine at mid RPM range and sprinkle Borax or Bonami? in the carburator. That would skuff up the cylinders so the rings would seat.
     
  9. AModelCat

    AModelCat Road Train Member

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    Funny you mention that @BoxCarKidd. I was told that thing with Borax not long ago by a coworker.
     
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  10. SophiaWYO

    SophiaWYO Bobtail Member

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    I was thinking this same thing. 255 miles to get to the dyno I would think the engine would have seated in by then. Cummins told me to change the oil after 5,000 miles to remove any metal debris left on the engine parts during manufacturing. Figured I'd pickup a 40,000 lb load and run it around 70 mph, maybe go up and down a few hills with the load. If I run from Wyoming to Chicago, Nashville, Atlanta, Ontario, CA then back to Wyoming that should give me just over 5,000 miles and plenty of decent hills.

    Thanks everyone for helping me decide. I'll see you out there once my engine is done!!

    Sophia
     
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  11. jamespmack

    jamespmack Road Train Member

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    Used to do this to 406 SBC on alcohol. Only way to get moly rings to seat. Still had to change oil every race.
     
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