Old timer told me I was using torque wrenches all wrong

Guy with 30 years on the line caught me torquing head bolts without a drop of oil on the threads... said I was basically guessing the real clamping force. Now I always lube the studs lightly with 30 weight, and my gasket failures dropped to almost zero. Has anyone else gotten a wake-up call on something this basic?

3 comments

3 Comments

ryan_barnes1mo ago

The 30% stat makes me cringe thinking about all those dry torqued bolts I did early on.

victorh811mo ago

SAE published a paper years ago showing dry threads can give you up to 30% less clamping force than lubed ones at the same torque value. That means your gasket is basically seeing half the pressure you think it is, which explains blowouts. Now I just hit every fastener with a light coat of oil and never had a comebak since.

kim.jake1mo ago

Wait, dry threads on head bolts? That's wild. How do you even get consistent torque that way?

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