Master tech told me I was overtorquing head bolts and showed me the torque wrench calibration date

I was doing a head gasket job on a 6.7 Cummins last month and a master tech from the shop next door walked by. He watched me for a second then said 'your torque wrench is lying to you man, check the sticker.' Sure enough it was 8 months past calibration and I was doing 280 ft lbs instead of 250. I bought a new Snap-on torque wrench the next day and re-did all the bolts. Has anyone else had a calibration issue bite them on a big job?

2 comments

2 Comments

fionaa351mo agoMost Upvoted

That calibration sticker thing is a trap a lot of guys fall into... but honestly the bigger issue nobody mentions is how you store your torque wrench between uses. I've seen guys toss them in the bottom of a toolbox or hang them by the head and it throws the calibration off way faster than just using it. The Snap-on one is good but even the best wrench goes out if you treat it rough.

tylerlane1mo ago

Man that's rough... 280 instead of 250 is a huge difference, especially on a Cummins head. I've been there though, not with head bolts but on a main cap job for a Duramax. Calibration slip was three years old, didn't realize till after I torqued everything and the block cracked the next day. Now I keep a logbook for my own wrenches and I always check the date before starting anything critical. Some shops think they can fudge the numbers but a few extra ft-lbs can warp a deck or snap a bolt real quick. Good call on buying a new Snap-on though those hold their calibration way longer than the cheap ones.