Results 1 to 8 of 8
  1. #1
    New Member
    Join Date
    Nov 2010
    Posts
    13
    Location
    South-East N.-B.
    Tractor
    Kubota L4240

    Default Glow plug / Starting issue

    Good evening everyone,

    I have been having problems with starting my tractor (Grand L4240) for a while and I am not sure if it's the cold weather or humidity that is causing it. I question if it's the humidity because everytime it has refused to start has been on humid days. I tested the glow plugs a few weeks ago with an ohm meter and they tested good. Today I decided to pull the plugs out and test each one individually to make sure they work and they all glowed fine.

    After re-assembling everything, I tested the voltage going to the disconnect before the glow plug and the voltage was the same as at the battery. After reconnecting the disconnect and turning on the ignition, there was 0 volt at the glow plugs. Has anyone seen this before? Any ideas what could cause this?

    Other than doing the above testes, I have cleaned and greased every connection I could find (at the battery, ground at the frame, at each glow plug) to make sure it is not a corrosion issue; I have checked all the fuses and they look fine; I also replaced one of the glow plug relays thinking it may be the culprit because one of the pins showed signs of overheating (blueish color). When I plug the block heater, the tractor starts fine.

    The next thing I am going to try is to disconnect the temperature sensor to make sure it hasn't gone bad.

    Thanks.

  2. #2
    New Member
    Join Date
    May 2011
    Posts
    6
    Tractor
    Montana 2840

    Default

    Based on what you have tested, it sounds like the glow plug relay. If that does not work you might want to check the injectors. They could be dirty. You can usually just take them to a shop and have them tested. In the past I have taken the hard lines off the fuel pump, spun them around so they face away from the motor and hook my injectors to them again so I could crank the motor and watch how they spray. If they are not atomizing the fuel properly it would take more heat to get the fuel to ignite. Which is why when the block heater is used the motor starts better.

  3. #3
    Super Member
    Join Date
    Sep 2000
    Posts
    6,595

    Default Re: Glow plug / Starting issue

    Key switch? Is the signal from the key getting to the relay? Have you jumped the relay from the battery and seen if the glows get hot?



    (just a guess)

  4. #4
    New Member
    Join Date
    Nov 2010
    Posts
    13
    Location
    South-East N.-B.
    Tractor
    Kubota L4240

    Default Re: Glow plug / Starting issue

    Quote Originally Posted by john_bud View Post
    Key switch? Is the signal from the key getting to the relay? Have you jumped the relay from the battery and seen if the glows get hot?



    (just a guess)

    Thanks for the input guys.

    john_bud: Yes I thought of the key switch as well. So I started by tracing the power from the battery to the ignition switch. Then to test the ignition switch, I disconnected the wiring harness to it and checked whether there was continuity as I turned the key from off to accessory, to glow, and start. It all tested fine. I also did this test with the wiring harness connected, and checking for power on each of the key positions and there was power.

    Once I knew I had power at the ignition switch I checked if there was power going to the glow plug relays. I pulled them out of their sockets and found that the sockets have constant power to one of the pins (4) and it switches to the opposite pin (1), when the key is turned to the glow position.

    Turning the key to the glow position, powers pin (3), which closes the contact between pins (4) and (1) transferring power to the glow plug wire. I also tested the glow relays directly on a battery and they worked fine.


    < ===============

    The following is my crude diagram of the glow plug relay:

    Glow Relay
    ----------

    Pin 1 |

    Pin 2 & 3 | |

    Pin 4 _


    ================ >


    After testing all of the above, I tested if there was power at the glow plugs and there was none. So I disconnected the wire right before the glow plugs and tested again and had power coming from the relay. As soon as I reconnected the wire to the glow plugs and tested again, there was no power. So I thought one of the glow plugs must be bad causing a short circuit. But when I checked the resistance of each glow plug, they tested fine ( A short would have resulted in no resistance ). But to make sure the glow plugs were good I took each one out and tested them on a battery one by one and after approximately 3 seconds they glowed. so I know they are good.

    Before taking out the glow plugs, I tried disconnecting the temperature switch to see if it was defective and indicating the engine wasn't cold; and therefore cutting the power to the glow plugs but it wasn't the case; it did not change anything.

    After, re-installing the glow plugs and the glow plug relays, I tried starting the tractor and it started right up. So now I am confused. I am thinking humidity is playing a role here, because by this time it got colder and wasn't as humid as it was the day before and in the morning. As mentionned before, everytime I have had trouble starting the tractor it has been quite humid out.

    Unless anyone else can think of something else I can test my plan for the next time it won't start, is to provide power to pin 3 of the glow plug relays by bypass the ignition switch. If that works it will tell me the ignition switch is bad. If it doesn't then I'll try taking out the relays one at a time and put a jumper between pins 1 and 4 of the relay sockets and if that works, I'll replace the relay.

    Happy Holidays!

  5. #5
    Elite Member Don87's Avatar
    Join Date
    May 2010
    Posts
    4,226
    Location
    SW Pa.
    Tractor
    Massey Ferguson GC2400

    Default Re: Glow plug / Starting issue

    Quote Originally Posted by KewlTracks View Post
    Thanks for the input guys.

    john_bud: Yes I thought of the key switch as well. So I started by tracing the power from the battery to the ignition switch. Then to test the ignition switch, I disconnected the wiring harness to it and checked whether there was continuity as I turned the key from off to accessory, to glow, and start. It all tested fine. I also did this test with the wiring harness connected, and checking for power on each of the key positions and there was power.

    Once I knew I had power at the ignition switch I checked if there was power going to the glow plug relays. I pulled them out of their sockets and found that the sockets have constant power to one of the pins (4) and it switches to the opposite pin (1), when the key is turned to the glow position.

    Turning the key to the glow position, powers pin (3), which closes the contact between pins (4) and (1) transferring power to the glow plug wire. I also tested the glow relays directly on a battery and they worked fine.


    < ===============

    The following is my crude diagram of the glow plug relay:

    Glow Relay
    ----------

    Pin 1 |

    Pin 2 & 3 | |

    Pin 4 _


    ================ >


    After testing all of the above, I tested if there was power at the glow plugs and there was none. So I disconnected the wire right before the glow plugs and tested again and had power coming from the relay. As soon as I reconnected the wire to the glow plugs and tested again, there was no power. So I thought one of the glow plugs must be bad causing a short circuit. But when I checked the resistance of each glow plug, they tested fine ( A short would have resulted in no resistance ). But to make sure the glow plugs were good I took each one out and tested them on a battery one by one and after approximately 3 seconds they glowed. so I know they are good.

    Before taking out the glow plugs, I tried disconnecting the temperature switch to see if it was defective and indicating the engine wasn't cold; and therefore cutting the power to the glow plugs but it wasn't the case; it did not change anything.

    After, re-installing the glow plugs and the glow plug relays, I tried starting the tractor and it started right up. So now I am confused. I am thinking humidity is playing a role here, because by this time it got colder and wasn't as humid as it was the day before and in the morning. As mentionned before, everytime I have had trouble starting the tractor it has been quite humid out.

    Unless anyone else can think of something else I can test my plan for the next time it won't start, is to provide power to pin 3 of the glow plug relays by bypass the ignition switch. If that works it will tell me the ignition switch is bad. If it doesn't then I'll try taking out the relays one at a time and put a jumper between pins 1 and 4 of the relay sockets and if that works, I'll replace the relay.

    Happy Holidays!
    How much power was there? Did you check with a multimeter or just a testlight. If using a testlight, is it LED or a standard bulb..........the reason I ask, is that an LED testight will show power with very small amounts of current. (low enough currents that won't light a regular bulb).
    Don

    MF GC2400, FEL, 60in.MMM, 5ft. Cultivator, Single Bottom Plow, Bush Hog RTC48 tiller, MF 2360 front mount snowblower, 5ft backblade. BXpanded Piranha toothbar.

  6. #6
    Silver Member Oldtink's Avatar
    Join Date
    Mar 2011
    Posts
    148
    Location
    Deere Pen or Dog house
    Tractor
    JD 3520

    Default Re: Glow plug / Starting issue

    KewiTracks Sounds like you're on the right track checking voltages and resistance. Your problem is "high resistance" in the circuit and that won't show up with voltage checks with no load on the circuit as you have seen. Keep tracing back from the glow plugs with the glow plugs turned on and you'll find the voltage drop and the open element.

  7. #7
    New Member
    Join Date
    Nov 2010
    Posts
    13
    Location
    South-East N.-B.
    Tractor
    Kubota L4240

    Default Re: Glow plug / Starting issue

    Don: I used a multimeter and it was over 12V, same as at the battery.

    Oldtink: if you think there is an open element somewhere, it has to be the disconnect before the glow plugs because it's the only thing I have not tested yet. I'll have to take that apart and take a closer look. Thanks.

  8. #8
    Silver Member Oldtink's Avatar
    Join Date
    Mar 2011
    Posts
    148
    Location
    Deere Pen or Dog house
    Tractor
    JD 3520

    Default Re: Glow plug / Starting issue

    Something is not "totally open" but of high resistance. If it was an open you wouldn't have measured 12v at the connection to the glow plug at any time. Rather think there is a bad connection somewhere, whether that be a switch or contact with dirty/burned contacts or a wire connector or even a relay socket itself.
    When you turned the glow plug switch on and measured 12vdc at the lead to the glow plug that was because there was no current flow in the circuit and once you made the connection to the glow plug the voltage "seemed" to disappear. The 12v is being dropped across something prior to the plugs. What ever it is it should be dissipating some heat.
    Wish I was there to help. I just love tracking this stuff down. Sorry I don't know the circuit better but I would take a good hard look at these relays.
    If the relay coils are working (should hear them click) and power is supplied to #4 and feeds #1 and you always have 12v on pin 4 but not pin 1 during glow plug operation then there is your problem, the relay contacts of 4 & 1 are fried. AND if these relays plug into sockets don't over look the sockets themselves as a possible bad connection.
    IF all else fails you can try holding the glow plugs ON and feel for a component getting hot.......or smoke!
    You'll find it but sometimes it's just time consuming and requires patients along with a good eye for burnt or discolored insulation.
    I wish you the best.

Similar Threads

  1. Replies: 8
    Last Post: 11-09-2012, 10:28 AM
  2. Glow plug issue.
    By Deezel in forum Kubota Owning/Operating
    Replies: 2
    Last Post: 08-18-2012, 08:02 PM
  3. 2003 Kubota L4310HST tractor- glow plug issue
    By sshure in forum Parts/Repairs
    Replies: 1
    Last Post: 04-13-2008, 08:45 PM
  4. TC33D Glow Plug Issue
    By Bob_Bullock in forum New Holland Owning/Operating
    Replies: 37
    Last Post: 06-10-2006, 07:15 PM
  5. New JINMA 284 Winter Starting... GLOW PLUG BASICS?
    By playing2win01 in forum Chinese Tractors
    Replies: 4
    Last Post: 02-04-2005, 10:01 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
© 2016 TractorByNet.com. TractorByNet is a registered trademark of IMC Digital Universe, Inc. Other trademarks on this page are the property of their respective owners.