Old timer yelled at me for using impact on glow plugs

I was swapping out glow plugs on a 7.3 Powerstroke last Tuesday and grabbed my impact gun without thinking. A retired mechanic who hangs around the shop just started screaming at me from across the bay. Told me I was gonna break the tips off and ruin the head on a $600 truck. Now I hand torque every single one to the factory spec, even on my own rig. Has anyone else learned something the hard way from a shop elder like that?

3 comments

3 Comments

paul_morgan1mo ago

Did you ask why the old timer told you that? Because he probably had a good reason from back when these trucks were still common on the road. I learned a similar lesson when a shop foreman caught me zipping valve cover bolts on a Cummins with an impact and he made me retorque every single one by hand, told me about a guy who stripped out four holes in a head and had to helicoil the whole thing. Its easy to get lazy with power tools but that split second of torque can crack a glow plug tip and then youre fishing pieces out of a cylinder with a magnet.

evanr791mo ago

Ngl though those impacts are fine if you've got a calibrated trigger finger and know the feel.

wren6521mo ago

That phrase "know the feel" is what gets me. I remember back when I was wrenching on my old Ford pickup, a buddy of mine swore up and down he could feel the exact torque point through a long ratchet handle. One day he was tightening down some header bolts on his Chevy and cracked a bolt right at the flange. He spent the next three hours drilling and extracting that thing while I just stood there watching. The problem is your hand and brain can fool you when you're tired or in a hurry. Those impacts have a habit of making you overconfident until you're dealing with a broken fastener and a long afternoon.