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Dynahoe Detroit 353 problem

Discussion in 'Tractor/Loader/Backhoes' started by ssrider, Oct 9, 2017.

  1. ssrider

    ssrider Member

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    Hello,
    I recently purchased a Dynahoe backhoe powered by a Detroit 353. It has a variable speed governer. I was having a problem with low power and slow throttle response when i first got it. I set the rack and adjusted the governer yesterday. I now have lots of power but throttle response still isn't right. When the motor is cold I have good response both up and down. But once the motor is warmed up to operating temp I am having a problem where it idles down very slowly. Sometimes it hangs at 1000 rpm for 5 seconds or so. Any ideas what I should be checking? Thank you
     
  2. Former Wrench

    Former Wrench Senior Member

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    A simple test would be to disconnect the linkage from the governor and operate it to see if you have throttle control issues. You might put vise grips on the handle for leverage.
     
  3. John C.

    John C. Senior Member

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    Kind of sounds like the buffer screw might be turned in a little tight. Also did you reset the air gap after redoing the rack?
     
    DB2 likes this.
  4. ssrider

    ssrider Member

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    I've disconnected the linkage and habe the same problem. The speed lever is returning to idle position no problem.

    For the buffer screw adjustment I backed it right out, set the idle, then slowly turned it in until the idle smoothed out. Is this the correct method? How do I set the air gap? Is that the 0.006 between the governer spring and the "plunger"?

    Thanks for the help I'm totally new to these Detroit's.
     
  5. John C.

    John C. Senior Member

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    Did you do the buffer screw when the engine was cold? That might make a difference.

    You are correct about the air gap. Someone on here should be able to tell you if that can make a difference or not.
     
  6. ssrider

    ssrider Member

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    I did the buffer screw with the engine warm. But I did set the air gap on a cold engine, and before I set the rack. Haven't checked it since. I'll check it out and see if it needs adjustment.
     
  7. ssrider

    ssrider Member

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    Okay so I warmed up the engine and checked the gap. It was about 0.008 so I re adjusted it to 0.006. Unfortunately it didn't help my issue. As I said earlier, the motor idles down quickly when not fully warmed up. But once warmed up it intermittently hangs up and idles down slowly.

    Also if I hold the throttle wide open, at operating temperature, the rpm will jump around between 2600 to 2800. Shoyld it be holding a steady RPM? Seems like its hunting which I'm not sure is normal.

    One thing I should add is that I set the rack on a cold motor. Is this procedure supposed to be done on a warm or cold engine?
     
  8. John C.

    John C. Senior Member

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    What are describing kind of sounds like a throttle delay they used in highway trucks years ago. I can't image something like that would be 3 53 industrial engine though. You didn't see anything that looked like a little pot with a piston hooked to the rack did you? Setting the rack can be done at any temperature as what you doing is setting an injector to the governor and then setting the rest to that single injector. Did you unhook the rack from the governor before setting the other two injectors to number one?

    Do you know anything about the history of the machine? Maybe it sat for a long time and has some rusted parts. You might try running it for a bit to see if things change over time.

    I don't know about how accurate the high idle no load speed will be on an old engine. Usually I would check the engine speed by stalling the torque converter if the machine has one. It's a more real world test.

    Hang out here for a bit as there are some gents far more versed in Detroit that me. I'm sure one will pop up soon.
     
    DMiller likes this.
  9. DMiller

    DMiller Senior Member

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    Should not have a delay unit anywhere on the rack. 53 series are pretty simple and sorrowfully can be stupid as well. Disconnect the rack from the governor with engine off, VALIDATE the rack rolls free and smooth NOTHING binding or dragging first to rule out injectors. That checks then is time to pull the governor off the end of the blower. Would need inspect the shaft, the support bushings/bearings and for excess play then really look at the flyweights, the weight contact points and the mechanism in general for wear patterns, for distress marks or damaged pivot point pins/bushings drillings and the retainer hardware. HAS TO BE positively PERFECT or will experience what you are dealing with in differing degrees. Could be a moisture intrusion damage(rust or corroded), or just flat worn slick.
     
  10. ssrider

    ssrider Member

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    Thanks for the replys. The machine had not sat for an extended period of time, the previous owner used it a handful of times per year. I did unhook the governer before setting the other 2 injectors.

    I had pulled the governer off a few days ago and briefly went over it. Everything seemed to move freely but perhaps I should do a more detailed inspection of it. Do you know if a new governer assembly can be purchased for a reasonable price?

    Tomorrow I'm going to inspect and set the rack again, just to rule that out for sure. John maybe your suggestion of running it for a while and seeing if it clears up.

    I also discovered I have a slight fuel leak from a fitting on the secondary fuel filter. I don't believe this would cause the issue I'm having though.
     
  11. Bill Smith

    Bill Smith Well-Known Member

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    My Detroit 671 600 cfm air compressor would speed up and slow down . Found out we had the wrong injectors in it
     
  12. ssrider

    ssrider Member

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    I currently have N50 injectors in it. Do you know if these are the correct ones?
     
  13. DMiller

    DMiller Senior Member

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    When you inspect the governor, will not stand out like a grinder mark, more than likely a step on a shaft or a wear spot to the weights at the contact region, very minor in appearance but at the right place will cause the governor to allow excess fuel then break over to slow drastically to repeat and repeat. May only look like a line but if can feel with a fingernail is probably too much. Usually occurs at the most loaded spot or often used throttle position. Check the rack pins for the same conditions. Anything that can momentarily stutter the free movement will cause this.

    Most of these were repairable by lightly sand flat spot edges or the step on a shaft out, sometimes just buffing the parts up.
     
  14. Bluox

    Bluox Well-Known Member

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    Post the info on your data plate. Did this problem start after you worked on it or before?
    Bob
     
  15. ssrider

    ssrider Member

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    The problem existed before I worked on it. After I set the rack the machine had way more power but still wasn't idling properly or maintaining RPM with the throttle lock.

    I just ran it for an hour or so. It's manageable for loader work because I'm using the foot throttle and can manually compensate for load. But with the throttle lock set and using the backhoe, it is basically unusable. If I set it at 2100, any movement of the hoe will drop it to 1500 or less. It sometimes will slowly come back up or just remain low until I adjust the throttle again. Idle it is hunting pretty bad. Randomly will climb to 1200 and then back down.

    I'm wondering if I should just order a re manufactured governer? I'm worried if I pull this one and tear into it i may not be able to find the problem, if it could be just a slight imperfection. What's your thoughts on this?

    Here's a few photos
     

    Attached Files:

  16. Bluox

    Bluox Well-Known Member

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    Your picture of the data plate missed the injector # but N-50's are used in 3-53's. If you PM me your phone # and when to call I will be happy to talk about this .
    Bob
     
  17. old-iron-habit

    old-iron-habit Senior Member

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    I think you are wasting your time and doing it no good trying to run it at 2100 RPM. The The 3-53s are typically screaming at 2700 on the governor. Open it up and let it scream. They have no power to speak of at 2100. 4-53s are typically set at 2400. Probably not going to change your problem but it should run better.
     
  18. ssrider

    ssrider Member

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    I have found the problem. I took the governer off and disassembled it. I found metal pieces/shavings, and a stray ball bearing in the lower housing of the governer.

    It looks to me like there should be ball bearings in the space where my screwdriver tip is. Can anybody confirm this?

    Also does anyone knoe where can I find replacement parts for this?
     

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  19. kshansen

    kshansen Senior Member

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    I pretty sure what you are point to are the races for the riser thrust bearing. Also the "fork" just below that looks to have some serious wear.
     
  20. Former Wrench

    Former Wrench Senior Member

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    It sounds like the sandwich bearing went bad. These are inexpensive and look like two stacked washers with ball bearings in between. They are the contact point between the circular motion of the engine and the mechanical action for fuel control of the injectors.