Used to just crank head bolts down by feel, now I actually follow torque specs to the letter

I used to work at a shop where the old timer taught me to just tighten head bolts till they felt right, maybe give em an extra grunt with a breaker bar. Did that for like 3 years on various diesel engines, never had an issue or so I thought. Then last fall I pulled a head on a 5.9 Cummins that had a blown gasket, and when I got the bolts out two of them were actually stretched, almost ready to snap. That scared me straight because a broken bolt in the block would have been a nightmare to extract. Now I always use a calibrated torque wrench even if it takes twice as long, and I write down the settings for each job. Has anyone else caught themselves slacking on torque procedures and then had a close call like that?

3 comments

3 Comments

robert_smith3621d ago

Is "almost ready to snap" really that close to actually snapping though? I've seen stretched bolts hold fine for years if you aren't pushing crazy boost.

charles91921d ago

Are we really acting like "almost snapped" means you've got a problem?

holly_green8221d ago

charles919 is kinda downplaying it but honestly that "almost snapped" part is the whole point lol. You don't realize how close you are to disaster till you see the metal starting to twist and neck down. robert_smith36 mentioning stretched bolts holding fine under low boost has a point but that's a gamble I'm not willing to take after seeing how thin those threads can get. Once you've had to extract a broken bolt from a block in a tight engine bay you'll never look at a torque wrench the same way. It's just not worth the what if when a good torque wrench and 10 extra minutes saves you a weekend of hell.