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  1. #1
    Bronze Member
    Join Date
    May 2005
    West Chester, Pa
    John Deere 4120

    Default 4120 smokes...

    My 4120, which has 111 hours on, developed a problem.

    I'm not sure exactly when, but it has been doing it for a while.

    It is an intermittant problem where the exhaust gets real smokey, it looks like oil smoke on a gas engine.

    When i check the crankcase, the engine oil level is fine, so i suspect it is injection pump related, something causing incomplete combustion.

    Anyway, the problem is that it doesn't do it all the time. It usually happens after I've been in the seat 1/2 hour or so. The engine changes tone, it gets like a real low rumble to it, and then tons of smoke out the exhaust.

    My dealer says they need to take it in to figure it out. i have two concerns, 1) that i pay them to take it in, and it doesn't do it, and 2) somehow they will telll me it is something i somehow did, and deny warranty.

    With 111 hours on the clock, is there any maintenance i should do before they come out?

    Thoughts appreciated,

    Thanks in advance,


  2. #2
    Veteran Member joes_427_vette's Avatar
    Join Date
    Aug 2004
    New Holland TC 55 DA, 4110 John Deere, HT 20 Bolens, 1456 Bolens

    Default Re: 4120 smokes...

    My 4110 will smoke under a heavy load. I use premiur diesel ( the best grade I can get ) but it still seems to have adequate power. My former 455 never smoked with 2000 plus hours on the clock. I noticed this one has a lower compression ratio. Don't know if this may have something to do with it. Only 30 hours to date.

  3. #3
    Gold Member
    Join Date
    Jul 2005
    saint leonard , MD
    John Deere 4320

    Default Re: 4120 smokes...

    Hi JT I had a simular problem with mine but it would lose power when it would happen. They had to reclock and shim the injectors, And replaced 1 injector. It took them 6 weeks to find the problem. Aparently they have the same problem with the skid steers at 300-400 hours with the same engines in them. I hope this helps.


  4. #4
    Veteran Member
    Join Date
    Dec 2004
    western NC
    JD 2320; 4520

    Default Re: 4120 smokes...

    I suspect you are talking of an injector problem. This has been a periodic issue with the PowerTech engines. The engine itself is likely fine, but you definitely do no want an overfueling situation, so I would run it in pronto. It should be covered since the tractor is under warranty. John Deere has had enough of these issues that they will take your concern very seriously. Bear in mind, they want you to buy green next time, and in most cases, will treat folks very well to get return business. That is a little dealer dependent though.

    John M

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