Took me 3 rebuilds to realize I was overtorquing head bolts like a dummy

I kept having head gasket failures on a 5.9 Cummins I was working on. After the third time pulling the head, I finally sat down and looked at my torque wrench calibration. Turns out I was using a 3/8 drive torque wrench that was way off for the final angle torque step. The shop I work at in Denver has a calibration guy come through every 6 months, but I never bothered to check my personal wrench. I borrowed a calibrated one from a coworker and suddenly everything felt different. The bolts actually moved smooth instead of that jerky feeling I thought was normal. Has anyone else had a torque wrench give them false confidence for months before they realized it?

3 comments

3 Comments

ellioth371mo ago

That feeling when you realize your torque wrench has been lying to you is honestly soul crushing. I had a similar thing happen with an older beam style wrench that I thought was bulletproof because it didn't have any fancy electronics to fail. Turns out the needle had gotten bent somehow and was reading about 15 pounds low across the whole range. Three oil pan gaskets later I finally noticed the leak pattern matched a classic uneven torque situation. Did you end up checking your wrench against a known good one after that or did you just toss it and start fresh?

william_garcia1mo ago

Man I feel that, I checked mine against my buddy's brand new digital one and threw the old one straight in the garbage after seeing how far off it was. Now I just budget for a recalibration every year like clockwork.

joel_clark371mo ago

Bad torque wrenches are like bad relationships, they lie to ya face for months and @william_garcia knows the drill.