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  1. #1
    Silver Member
    Join Date
    Nov 2005
    Posts
    114
    Tractor
    JD 4100

    Default JD4100 won't start easy...it takes some time. Glow plug issue?

    I have a JD 4100. It had some electrical problems last year amd I ended up replacing the voltage regulator with a 40amp alternator. A few weeks after, it started having trouble starting.

    When I turn the key, it doesn't turn over for about 30 seconds and then shoots a lot of smoke.

    I suspected a glow plug issue since after you start it once, it turns right over every time until it cools down again.

    I traced the wires to the glow plugs and I tested them. They get battery power for 3 seconds and then they shut down. All 3 get power.

    Does it mean that there is something wrong with the glow plugs? Do they all go bad at once?

    What I don't understand is, when I turn the key to "on", the dash glow plug light lightbulb illuminates but it doesn't shut off until I move the key to start. Shouldn't it shut off after 3 seconds when the battery current going to the plugs shuts off?

  2. #2
    Advertiser kennyd's Avatar
    Join Date
    Jul 2003
    Posts
    11,863
    Location
    Westminster, MD
    Tractor
    John Deere 4110, 455

    Default Re: JD4100 won't start easy...it takes some time. Glow plug issue?

    A few quick things since I have limited connectivity now:

    -I don't believe the 4100 has a glow plug light, can you post a picture? My 4110 does not have one, the GP's are only active when the key is in the start position.
    -You can test the GP's with a ohm meter, just remove the wire and test the tip of the plug to ground, you should see near zero resistance.
    -Your saying you hold the key in start for 30 second before the engine turns over?
    KennyD
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  3. #3
    Silver Member
    Join Date
    Nov 2005
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    114
    Tractor
    JD 4100

    Default Re: JD4100 won't start easy...it takes some time. Glow plug issue?

    I always thought my jd4100 had a glow plug light on the dash. If i recall, there is a battery light and a glow plug light. the only thing is, the glow plug light on the dash does not shut off after 3 seconds, even though the current from the battery to the glow plug, cuts off after 3 seconds.

    how do i test resistance on the glow plug. I am not used to using ohms.

  4. #4
    Gold Member
    Join Date
    Jan 2006
    Posts
    355
    Location
    Stone Mountain, GA
    Tractor
    Case 1210, Mitsubishi D2050

    Default Re: JD4100 won't start easy...it takes some time. Glow plug issue?

    Hi -
    You are saying some confusing things. I assume when you say "When I turn the key, it doesn't turn over for about 30 seconds", you really mean that the motor is turning over, but it doesn't start firing on fuel for 30 seconds, followed by a lot of smoke. You need to be precise in what you are saying.
    You then say "I traced the wires to the glow plugs and I tested them. They get battery power for 3 seconds and then they shut down." I assume you mean that you saw power at each of the glow plugs for 3 seconds, but don't know how to test them.
    Ok, glow plugs are nothing but a wire going to a nichrome element, similar to a heater element in an electric heater, but the element is very short. They will have 3-20 ohms of resistance each. To test one, put an voltmeter on the ohms setting, disconnect the wire from the glow plug, and put one meter lead on the glow plug and one on the motor block. Each should measure the same.
    I suspect that the glow plugs are ok, as they won't heat up in 3 seconds; and therefore will not help the engine get started. Depending on the ambient temperature, they may not be needed to start the tractor at all. But if they are, typically you heat them up by turning the ignition switch to a "heat" location, and then on to start.
    It is possible that the ignition switch is faulty, along with the glow plug relay, or possibly a bad connection in the circuit between the ignition switch and the relay or between the relay and the plugs.

  5. #5
    Silver Member
    Join Date
    Nov 2005
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    114
    Tractor
    JD 4100

    Default Re: JD4100 won't start easy...it takes some time. Glow plug issue?

    I apologize for not being more exact with my descriptions. It isn't hard to tell that I am not very experienced with engine problems. The problem is, I don't really know anyone in my area that can help me or that I trust to help me. so I am on my own.

    I have a JD technical manual and my thought was that if I can go to the last place(the glow plugs) and check for voltage there, then everything else between the battery and the glow plugs must be good. I tried to test the glow plug relay but I can't find it. I think it is buried.

    I am killing my starter by cranking on that thing so hard to get my tractor to start.

    All I know is that the wire that leads to the glow plugs get battery voltage for around 3 seconds, then then get no battery voltage after that.

    What will checking the resistance of the glow plug show me? That they work? Are you saying that 3 seconds is not long enough to help the engine start? Should it be longer? The manual says the glow plugs get 3 seconds of battery voltage......

    thanks for your help and patience!!!

  6. #6
    Gold Member
    Join Date
    Jan 2006
    Posts
    355
    Location
    Stone Mountain, GA
    Tractor
    Case 1210, Mitsubishi D2050

    Default Re: JD4100 won't start easy...it takes some time. Glow plug issue?

    Hi-

    I am not trying to give you a hard time, just pointing out that it is hard to provide you a best guess if you aren't specific in what the problem is. With that said, I will be glad to help as I can.

    It really is hard on the starter to crank an engine that long as you say. For the engine to start, there need to be 4 things: 1) adequate compression (rings not too worn); 2) fast enough cranking speed; 3) fuel; 4) enough heat to start the combustion cycle. If the ambient air temperature is above 45 or so degrees, typically a diesel engine will start easily enough with or without glow plugs. Some engines are the exception to this rule, and are referred to as "hard starters" as they always take glow plugs to get them going. I have a Mitsubishi 4 cylinder diesel tractor that is this way, it runs fine, but requires glow plugs or a long crank time.

    Three seconds is an inadequate period of time for a glow plug to heat up. If the voltage to the plugs is sufficient (10 volts or more) and you get a resistance reading across all of them, then the problem is before the glow plugs. There is probably a glow plug relay which may be faulty, a bad connection or wire (between the glow plugs and relay, or relay to ignition switch), or a bad ignition switch.

    You mention that they are on for 3 seconds. Does this happen every time? If so, then it sounds like there is probably nothing wrong with the glow plug circuit, there is probably something else like a oil pressure sender that is bad. Some tractors (sorry, I don't know your exact engine) will cut off the glow plugs and probably fuel when there is a sensor that says something is wrong (like low oil pressure). Some modern tractors require that someone is sitting in the seat before they will start, that the tractor is in neutral, etc.

    Hope this helps.

  7. #7
    Silver Member
    Join Date
    Nov 2005
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    114
    Tractor
    JD 4100

    Default Re: JD4100 won't start easy...it takes some time. Glow plug issue?

    I took absolutely no offense at your request for me to be more clear. I completely understand.

    I removed a glow plug and brought it to my JD dealer and he said he tested it and it shows that it is faulty because it is "open". He said they don't usually fail like that.

    I ordered 3 more glow plugs and I am awaiting their arrival in about a week.

    I am worried I might have a relay or glow plug module problem but I tested them the best I can and according to my "amateur" tests, they seem fine. One thing that makes me think they are fine is: the glow plugs are getting 3 seconds of voltage and then it stops. If I had a relay problem, wouldn't the plugs either be getting NO voltage at all or CONTINUOUS voltage?

    I just don't want to have my new glow plugs fail too.

    thanks

  8. #8
    Gold Member
    Join Date
    Jan 2006
    Posts
    355
    Location
    Stone Mountain, GA
    Tractor
    Case 1210, Mitsubishi D2050

    Default Re: JD4100 won't start easy...it takes some time. Glow plug issue?

    You are correct in your assumption that the glow plugs should get a certain amount of time on, and then either be manually (via the starter switch) or automatically cut off. Almost all glow plugs that I am aware of take 5+ seconds to heat up, and typically are held on for 20+ seconds overall. For them to fail open means one of two things to me, either 1) manufacturing slight defect, which fails after a number of uses; or 2) they are held on longer than several minutes, which will cause them to burn out sooner than later.

    Bad relays can act a number of ways, 1) Failed open (no voltage to plugs); 2) Failed closed (continuous voltage to plugs; or 3) Intermittent (voltage off an on depending on it's mood).

    Does your tractor have an ignition switch with a "heater" position, to turn on the glow plugs? If not, what turns the glow plugs on?

    Hope this helps,
    Tom

  9. #9
    Veteran Member
    Join Date
    Dec 2000
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    1,709
    Location
    Southern VT, Southern ME
    Tractor
    John Deere 4100 HST /410 FEL, R4s

    Default Re: JD4100 won't start easy...it takes some time. Glow plug issue?

    You could cycle the key switch back and forth several times each time the timer clicks off before you try to start the engine but power to the glow plugs is also energized when you turn the key to the start position so you can try this procedure for easier starting...either move the shifter lever into gear, or turn the pto switch on, and then turn the key to crank and hold for several seconds. The engine won't turn over, but the preheat will work. After a few seconds, move back whatever switch you used to cancel the starter engagement back to it's normal position and start the tractor, with less cranking and less smoke. Thats how I start my 4100

    Dave

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