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Glow plugs gone haywire.

Discussion in '1982-Present GM Diesel' started by 6.2puller, Sep 20, 2004.

  1. 6.2puller

    6.2puller 1/2 ton status

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    Tonight my glow plugs started cycling after 20 min at 55+MPH. The engine was well up to temp running around 190 according to the stock gauge. I shut it down and started back up and same thing. Is my glow plug timmer shot?

    What are the pros and cons of replacing it vs going to a manual switch for the plugs?
     
  2. Pookster

    Pookster 1/2 ton status

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    Manual is better, I think I might do that with my truck- There's a temperture range that my truck doesnt like (namely, around 75-85 degrees). When the engine is cold, and between that temperature, sometimes, the glow doesnt cycle. Below that, its been pretty good
    If you go manual, you should get the new plugs so they dont burn out
     
  3. FWP

    FWP CRS

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    Haven't done alot of research on the controller, so I can't help there, but I do know this. If my controller ever goes out, and I can't fix it myself, I'm putting in manual control and 60Gs like Rene did(simple and easy to fix)
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    it's an easy and inexpensive modification. As Pookster said you should swap in some Kennedy GP's or at the very least some AC60G GP's to prevent swelling the tips if you glow them too long.

    I installed a momentary push button so they can't accidentally be left on, and use the seat belt light as a 'timer'. It stays on roughly 8 seconds...which is fine with a cold engine down to 50 degrees or so. Much colder and I let em glow for another 2-5 seconds. You get a feel for it pretty quick. When the engine is even remotely warm I don't bother using the GP's.

    If you want to do the manual switch just find and trace the little blue wire to the controller at the back of the motor. Cut the little blue wire about 6" away from the controller and pull it back out of the harness. Pull the wire through the firewall somewhere and attach the blue wire to one side of your switch. Attach a ground wire to the other side of the switch.

    Now when the key is turned to the 'run' position if you push the button the GP's will come on (with the glow light) until you decide they're warm enough...and they won't cycle for the hell of it when the truck is warm.

    Rene
     
  5. 6.2 man

    6.2 man 1/2 ton status Premium Member

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    Mine did that one time and it was low voltage .I had a bad alternator ?
     
  6. 6.2puller

    6.2puller 1/2 ton status

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    What is the other wire on the solenoid for the glow plugs? Is it always hot and when you ground the blue the plugs come on?

    Am I going to have issues in the AM when I head to work do you think? And more importantly if it runs fine in the AM but the plugs keep cycling what should I do for a quick fix to get to work? Maybe unplug the glow plug solenoid once the motor is running? I don't want to swell these plugs up any worse than they probably are befor I swap them this weekend.
     
  7. 6.2puller

    6.2puller 1/2 ton status

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    Little update. When I looked under the hood durring the daylight hours it became evident that low voltage was the problem. The Alt. belt was nicely wraped around the fan.
    Pulled out my spare belt from behind the seat and back to normal.
    I was quite surprised that the diesel can run for 30min (32mile trip) with no alternator. I know when it fell off now because the engine felt different as soon as the belt was wrapped up. I had the heat/radio/lights all on and the voltmetter was still in the mid range. Lower than normal but not bad. I started the truck 2-3 times that night to see if the glow plugs would resset then started it in the AM after fixing the belt. No problems with lack of juice /forums/images/graemlins/thumb.gif I am a lot less conscerned about my first new england winter with the diesel as my primary driver.
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I drove over 60 miles at night without a working alternator when I still had my 350, battery was deader than dead but the truck was still running. Just had no lights or anything else and it was starting to run weird.

    A diesel uses a fraction of the electrical power a gasser does and has double the batteries, so you likely could have gone quite a bit further...

    Glad to hear you got it figgered out.

    Rene
     
  9. Drey

    Drey 3/4 ton status

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    My belt fell off on a 70 mile drive, and i drove it that night again. The next day i drove it to work, and back up here before i realized i had no alternator belt.
     
  10. Pookster

    Pookster 1/2 ton status

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    I dont even think the diesel needs electricity. Unless you got an electric pump /forums/images/graemlins/frown.gif
     
  11. Blazr77400

    Blazr77400 1/2 ton status

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    It does need power to the pink wire on the pump. If it doesnt, it wont let fuel to the injectors. /forums/images/graemlins/truck.gif
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Power to the pump...plus whatever accessories are running. Not much draw if you know you have a problem and you're careful with what you use and for how long.

    Rene
     

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