The 6.7 Powerstroke glow plug harness is not a 'when it fails' part, it's a 'check it first' part

I keep seeing guys at the shop in Denver replace entire glow plug sets when a truck has a hard start, and they skip the $80 harness. That harness gets brittle after 50,000 miles in our climate, and a bad connection on cylinder 3 or 5 will mimic a dead plug. I've fixed three rigs this month just by swapping the harness. How many of you actually test the circuit before pulling the valve cover?

3 comments

3 Comments

emmas1920d ago

Okay, but is it really that big of a deal? You say it gets brittle after 50,000 miles, but what if the truck isn't having problems? I get checking it for a hard start, but calling it a "check it first" part for every single job seems like overkill. How many of these harnesses actually fail without any other symptoms? It just sounds like an extra step that turns a simple plug change into a bigger thing.

umamartin20d ago

Watch a coil boot tear because the wire wouldn't bend. Seen it. That brittle plastic cracks when you move it, not before. Now you're stuck ordering a new harness anyway, but your truck is apart. It's cheap insurance to look first. A five minute check beats a two day wait for parts.

julia_lee19d ago

Right? It's crazy not to check the cheap part first. I watched a buddy waste a whole weekend on plugs when his harness was just cracked at the connector.