PSA: Stop replacing glow plugs on cold starts without checking this first

I see too many guys throw new glow plugs at a hard start and call it fixed. Most times, the issue is with the relay or wiring harness corrosion. Grab a test light and check for power at the plug connector before you tear anything apart. On a 6.7 Powerstroke last week, a bad ground connection mimicked a dead plug. Cleaning the terminal fixed it in ten minutes, saving the customer a full set of plugs. Always verify the simple stuff before assuming the part is bad. It saves time, money, and stops comebacks.

2 comments

2 Comments

dylanbell4d ago

Yeah my buddy had a similar thing happen with his older Ford. Truck would crank forever on cold mornings, he bought a whole set of plugs ready to go in. Turns out the glow plug relay was just sticking sometimes. A couple taps with a screwdriver handle got it working until the new one came in. He wasted an afternoon for nothing, all because he didn't check for power at the rail first.

piper4704d ago

That sticking relay is a classic issue, @dylanbell. I always keep a multimeter handy to check power before pulling parts.