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That old timer at the parts counter got me thinking about glow plug maintenance
I was in at the local Cummins dealer in Lubbock last Tuesday picking up a set of injectors for a 5.9. This grizzled old guy next to me starts chatting while we wait, says he's been turning wrenches since the 70s. He goes off about how he replaces glow plugs every 50k miles on his own truck, even if they test fine. I always figured if the multimeter says they're good, leave em be. But he told me about getting stranded in a blizzard in 1985 because a glow plug failed internally after just passing a test. He said the electrical resistance lying to you is the number one hidden failure. Made me wonder how many trucks I've sent out with borderline glow plugs that could pop any time you need them most. Any of y'all run into glow plugs testing good but still causing hard starts?
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jenny471mo ago
Pulled a set out of a 7.3 last month that ohmed out perfect. Put a load tester on em and three dropped voltage instantly. That old timer's not wrong.
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holly_reed551mo ago
jenny47, that load tester story hits close to home. I had a 12 valve that would fire right up every morning but start missing like crazy after 30 seconds of glow plug cycling. Ohm test was perfect. Turned out the relay was dumping too much voltage and the plugs couldn't handle it. Makes you wonder how many borderline failures get written off as "just old batteries" or something. What brand were those plugs you pulled out?
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