Runaway diesel

Discussion in 'The Garage' started by telejojo, Jun 13, 2018.

  1. telejojo

    telejojo Been here awhile

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    I have a 20hp 2 cyc. diesel motor in my little farmpro tractor.I cranked it up today and it went wide open the throttle or shut off had no effect on it. I had to cut the fuel line to get it shut off before it blew up. What could cause this the injecter pump?
    #1
  2. PineyMountainRacing

    PineyMountainRacing Oops....

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    on some of my smaller Diesel engines, there is an electrical solenoid that shuts off fuel when you turn the ignition off. I have had more trouble with the engine shutting off as soon as I release the key (from start to run position). Usually that’s an electrical connection. Never had one start and run wide open, and not be able to shut it off. and i would think it would run at whatever throttle setting you have selected, not WOT.
    #2
  3. HeavyMetal

    HeavyMetal Been here awhile

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    Governor is stuck. Maybe that run loosened it up and maybe not. I would repair the fuel line and try it again. You can shut it down by blocking off the air intake with a board. Make sure you have access to it. Hopefully nothing was damaged.
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  4. ozmoses

    ozmoses .

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    ^^^^^^^This.
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  5. larryboy

    larryboy Chopper Rider

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    Is there any oil left in it?
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  6. hock2e

    hock2e This is a bad idea, but I'm all about bad ideas.

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    This may sound funny but check the oil level. If it's over serviced the excess oil can get sucked into the intake and cause it to run wide open. Seen it happen on a Kawasaki Diesel 4010 Mule.
    #6
  7. shovelstrokeed

    shovelstrokeed Long timer

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    Good question, diesels don't much care where or how they get fuel and crankcase oil will do just fine.
    It is doubtful it even has a throttle plate, just a hole for air intake. There will be an air cleaner though and that can/should be removed before checking the oil and starting it again. Have a chunk of plywood handy to block that air intake hole.
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  8. CaseyJones

    CaseyJones Ridin' that train

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    ^^^THIS^^^

    Back when I was going to school at Kent State...the students ran the bus line, the Campus Bus Service. It was the bus line for the whole county, Portage County...even ran commuter runs into Cleveland. One-hundred-percent student run.

    Except for four Gillig buses, the whole fleet was GMC New Look buses, with the V-drive and Detroit Diesel V-6s. And runaways...well, one never happened when I was working with them, but ALL drivers were trained on what to do. There was, from the driver's chair, a control that would shut off all air to the engine. We were admonished, at training, that if the engine started revving up with no throttle, and smoking heavily, CUT OFF THE AIR. Eight seconds, approximately, was the time the operator had - after that it wouldn't matter; the engine was going to race up until something failed.

    The cause was that when rings would get overly worn, or a seal fail, the engine would start consuming its own crankcase oil as fuel.
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  9. gonerydin

    gonerydin Been here awhile

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    For hours of entertainment search YouTube for "run away diesel".


    Sent from my iPad using Tapatalk
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  10. MJSfoto1956

    MJSfoto1956 Adventurer

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    had a turbo blow a seal in my VW diesel -- sent oil into the intake and it too would not stop. Had to step on the brakes to stop it.
    #10
  11. broncobowsher

    broncobowsher Long timer

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    Many small diesels have a compression release that is usually used to help start the engine. Pull that will stop a runaway as well.

    But what you describe, probably a stuck governor. It thinks the engine isn't up to speed yet so it adds more fuel, and more fuel, and more fuel.

    Another one is a failed seal. A bad pump can drain diesel into the crankcase. Fill the oil with diesel. Dipstick will tell.
    #11
  12. ttpete

    ttpete Rectum Non Bustibus

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    Jimmy 2-stroke diesels usually ran away because of leaking blower oil seals. Some of the inline engines had an overspeed trip mechanism that slapped a metal flapper door over the intake when the speed reached a set point. We had some gensets that had to be test run every so often, and the last check was to hold the governor down until it tripped out.

    We also had big generators that used GM 8-278 engines. They were straight 8s about 10 feet long and we had plywood pieces handy in case of a runaway.
    #12
  13. C Squared

    C Squared Now with TURBO!

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    Had a buddy who had a Golf Diesel from the late 70's. When the rings got worn and the cylinders... It would occasionally runaway on the blow by oil from the rings. Was kinda exiting..
    #13
  14. dtysdalx2

    dtysdalx2 PITA but useful

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    Good thing I've never owned a diesel! :eek7
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  15. victor441

    victor441 Long timer

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    Some of the DD V's had that feature too, I used to maintain a Detroit 24V71 that did, probably a retrofit...an impressive engine, 4 blowers PLUS 4 turbos for the 24 cylinders (it was basically 2 12V71's bolted together) Also had a 671 Detroit Diesel at another site, the original configuration from waaay back in 1938 and beautifully made...then realized where the 671 blowers that dragsters used back in the day came from. LOTS of history associated with them and some are still out there working 80 years after the 71 family was introduced.
    http://www.dieselduck.info/historical/01 diesel engine/detroit diesel/index.html#.WyHfYe0vyto
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  16. broncobowsher

    broncobowsher Long timer

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    Cutting the fuel supply (literally) stopped the engine. So the run away was from diesel being injected and not oil out of the crankcase. Problem is in the injector pump. Being a tractor engine it is likely a constant speed governor. Weight/spring broke/stuck in the governor in the injection pump. It is now going to be air locked as well, which is one of the better outcomes that could have happened.

    If the tractor has a manual transmission another way to stop it would have been to put it in a high gear, hold the brakes, let the clutch out and stall it.
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  17. RustyStuff

    RustyStuff Long timer

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    Grandpa had it happen in his semi back in the 70's when he was going up a mountain pass. Turbo seal failed and it started pumping all it's engine oil into the intake, held like 15 gallons of oil. Said the truck had never made it up that pass so fast, it was like it had twice the power. It ran out of oil and died.
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  18. CaseyJones

    CaseyJones Ridin' that train

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    I learned a bit from that.

    Didn't know; but it's the turbocharger seals that most-commonly causes it.

    Also, how freakin' COMMON it seems to be. There's dozens of vids.

    Then, how to stop it before a bearing goes. A block of wood will bring the speed down but unless you can get a perfect seal against the air plenum, it won't shut it down.

    A CO2 fire extinguisher can kill it dead - again, depending on a number of things. Might save the engine, though.

    And, of course, if you can keep your wits, and have a manual gearbox...just put it in high and dump the clutch. You'll buy a new clutch - but that's cheaper than a new engine.
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  19. telejojo

    telejojo Been here awhile

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    It was blowing black smoke so it may had oil getting past the rings. I will check the oil fix the fuel line and try it again.May put me a ball valve in the fuel line to shut off if needed.
    #19
  20. ohgood

    ohgood Just givver tha berries !!!

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    neutral?
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