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New or Overhauled Engine break-in

Discussion in 'General Industry Questions' started by spitzair, Jun 20, 2020.

  1. spitzair

    spitzair Senior Member

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    Hello Everyone,
    I recently rebuilt the engine in my Bobcat 732 and am wondering what is the best break-in procedure I should be using? The book really doesn't say and doing a google search gives all kinds of different opinions that are sometimes quite contradictory... This particular engine is a small Ford industrial gas engine if that makes any difference...
    Thanks guys!
     
  2. funwithfuel

    funwithfuel Senior Member

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    I have always fired it up , established oil pressure and poured the coals to it under load until the thermostat opened and kept it @ WOT for 10-12 minutes. It promotes ring seat and wears in the tappers to the cam. Make darn sure your cooling system is purged of air.
     
  3. lumberjack

    lumberjack Senior Member

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    Of the millions of used machines that have been sold, have you ever seen an ad having anything related to how the engine was broken in?

    Fire it up, watch the gauges, and put it to work.
     
    Jonas302 likes this.
  4. John C.

    John C. Senior Member

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    Diesels need to be loaded up pretty quickly after the first start up. When I was doing them all the time the procedure was generally all the same. Make sure fluids were at the proper levels. Pre-lube the engine if possible. Make sure all the air is out of the cooling system. Light off for a few minutes to check for leaks. Shut down and check levels again. Start and low idle for five to ten minutes. Gradually raise the RPM to high idle and then start putting a load on. If you have a machine with a torque converter, then do stalls on and off for at least a half an hour. Run the torque temp up just below the hot mark and then release till the gauge is at normal temp and repeat. If you have a hydraulic machine, then find a way to load with the implements. You need to pull the engine RPM down at least a couple of hundred and maintain for a bit. After that do a cool down for ten minutes or so, shut down and recheck levels. You should be good to go after that. I also change engine oil at about half the usual hours on the first go round. Then will be wear in debris in the bottom of the pan and in the oil filter.
     
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  5. Welder Dave

    Welder Dave Senior Member

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    A gas engine in a skid steer I think just use it. Skid steers normally run full throttle so just vary the load occasionally without lugging it too much.
     
  6. spitzair

    spitzair Senior Member

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    Thanks guys, I appreciate your replies. One of these days when I have something for the machine to do I will do as suggested. I have new filters and oil on hand and after the first hour or so I will do a full oil change and cut the filter open to make sure there's no massive chunks in there...
     
  7. funwithfuel

    funwithfuel Senior Member

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    If I rebuilt something, it gets baptized in fire. I will never give someone something I haven't personally beat the snot out of first. That way if something goes sideways, it happens to me.
     
  8. Welder Dave

    Welder Dave Senior Member

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    You can go more than an hour on the break in oil. Just use it like a new machine. Change the oil at about 50 hours.
     
  9. funwithfuel

    funwithfuel Senior Member

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    What kinda cam is in it? Roller or flat tappet? Oil selection is critical.
    Gotta have zinc for flat tappet
     
    mg2361 likes this.
  10. skata

    skata Senior Member

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    This is the most important thing . If it's flat tappet, you should follow what's recommended. If it's a roller cam, then the only thing breaking in are the piston rings. And they usually say run it hard to break them in. Don't do extended idling.
     
  11. Welder Dave

    Welder Dave Senior Member

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    Remember it's a 4 cylinder Ford gas engine similar to a Pinto engine.
     
  12. spitzair

    spitzair Senior Member

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    Thanks guys, It's a flat tappet cam, and one of my co-workers gave me a zinc additive to put in the oil. I'm waiting for something for it to do that will give it a good workout so I can run it hard as you guys are suggesting. Here's a picture of the engine back in the machine.
     

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    Last edited: Jun 24, 2020
  13. funwithfuel

    funwithfuel Senior Member

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    It's a little late to ask... were the cam and lifters replaced? Did you coat em up good with the assembly lube recommended? This little bit is where everyone has their make or brake moment. Is it hydraulic lifters or solid tappets?
     
    Last edited: Jun 24, 2020
    mg2361 likes this.
  14. spitzair

    spitzair Senior Member

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    I reused the original cam and lifters, they measured out to new spec so I lubed them up generously and reinstalled them. They are solid tappets.
     
  15. funwithfuel

    funwithfuel Senior Member

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    As long as everyone went back where they came from, you'll be fine. Still need zinc, but the break in period is less critical if you're using a used cam. New cam and lifters have to get married. That's why the prolonged high rpm break in. They're basically wearing into one another for long life.
     
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  16. spitzair

    spitzair Senior Member

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    Yep they sure did, I made sure of that. Hopefully one of these days I can run it hard for a while and see how it does.
     
    funwithfuel likes this.