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Can a glow plug test good but be bad?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by chris142, Jul 9, 2019.

  1. chris142

    chris142 Full Access Member

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    Got the 1/2 second flash instead if a steady on gp light. Tested them with a test light using the positive battery terminal one at a time and they all lit up the test light. I have in the past eliminated the electrical connection on the fender that burns up. Bad controller?
     
  2. Skidtech

    Skidtech Full Access Member

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    What kind of test light are you using? If it's an led light they will almost always test good when they are bad. You need a test light with a traditional bulb.

    Sent from my LG-H700 using Tapatalk
     
  3. chris142

    chris142 Full Access Member

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    Good question. Its the one that the cornhole guy had. It has a built in voltmeter. Likely l.e.d. I will find one with a bulb and try again. Thx!
     
  4. Skidtech

    Skidtech Full Access Member

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    Ya that will be led. If u have a harbor freight near you they have the normal bulb ones for a few bucks.

    Sent from my LG-H700 using Tapatalk
     
  5. chris142

    chris142 Full Access Member

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    OK I got one with a light. All the glows checked out OK. Had O'Riley's bring out a controller. It didn't look anything like mine,looked more like the stratosphere in Vegas.
    Same with vatozone and crappa.
    Gave up on getting a new one today. Called a friend that used to have an idi. He has a junk engine in his back yard and i snagged the controller off it.

    Went home and spent an hour laying over a 220f 420cuin engine. So far it seems to be working.
     
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  6. Shadetreemechanic

    Shadetreemechanic Full Access Member

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    Yes they will test good even if they are bad. The only foolproof test I know is to pull them and put 12v to them. Often when they test good and are bad if you pull them you will find that only a small portion of the tip gets hot at all. There is enough continuity for the ohm tester, but not enough to heat well.
     
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  7. BeastMaster

    BeastMaster Full Access Member

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    Maybe we should be testing with an ammeter? Anyone know how much current these draw? My SWAG is maybe 10 to 15 amps each?

    Next time I have a few loosies in hand, I'll get my old Triplett and measure em.

    Anyone familiar with these?

    https://sub.allaboutcircuits.com/images/50024.jpg

    They work by sensing the magnetic field around a wire carrying dc. You put the wire in the slot in the back, and it's field will deflect the pointer. Very crude, but simple, and doesn't require cutting the wire or damaging insulation.

    I have not seen one of these in years. Sure wish I had bought a few of these... Like, uh, 50 years ago....
     
    Last edited: Jul 10, 2019
  8. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    Total current draw on a healthy system is in the 200-230 amp range. :Thumbs Up
     
  9. BeastMaster

    BeastMaster Full Access Member

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    25 to 30 amp each, eh? Thanks!

    Looks like I'll have to make really sure my batteries are healthy... That's a helluva lotta load... Then cranking that big IDI on top of that?
     
  10. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    Yep! I was pretty skeptical at first but did the test myself with a clamp meter that only goes to 199A and it said OL for Over Load. Lots of info out there on it, especially on FTE if you want to Google for more.
     
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  11. rhkcommander

    rhkcommander Full Access Member

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    theres a reason we use two batteries often!

    depends on the glowplugs you use too, 6V plugs like bosch work FANTASTIC on a pushbutton setup but are easy to burn out because they get so hot so the controller will kill them, so its 100% a no-go with the controller. The motorcraft berus in my SWAG run cooler and thus can take more abuse from the controller. My old blown out engine would start great on bosch, and barely on beru. I've heard OK things about wellman, but again I would only use motorcraft beru with a controller. Pushbutton opens a whole new world.

    Gotta remember how old these GPC are, the technology in them isn't very advanced at all...
     
  12. chris142

    chris142 Full Access Member

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    It was definitely the controller. Back to normal starting. I have beru glow plugs i i installed back in 2012 and so far they still work.
     

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