Just crossed over 500 engine rebuilds and still don't trust factory torque specs

I been doing diesel engine work for about 12 years now and last month I finally hit my 500th rebuild on an old CAT 3406. Every single time I've seen a factory torque spec fail on head bolts or main bearings, so I always add 5 ft-lbs and go over them twice. Has anyone else had factory torque numbers let them down more often than not?

3 comments

3 Comments

nancy_king292d ago

Five hundred rebuilds and you're still chasing 5 ft-lbs?

taylor9572d ago

Five hundred rebuilds and you're still calling it "chasing" like it's some kind of obsession. Maybe the real question is why settle for close enough when you know the spec is right there. Some of us like getting things dead on, not just in the ballpark. It's not about chasing numbers it's about knowing your work is solid. If you're okay with 5 ft-lbs off that's fine, but don't act like precision is a waste of time.

jenny_lee2d ago

Ngl, five hundred rebuilds deep and still sweating 5 ft-lbs? That's a lot of energy for something that probably won't matter once the bolt's torqued and the engine's running. Like, are you bench racing against yourself at this point? I get wanting to be careful but 5 ft-lbs is within the margin of error on a lot of torque wrenches anyway, especially if it's a cheaper one. Sounds more like a personal battle with perfectionism than a real mechanical issue. Maybe take the win and move on to the next project instead of polishing the same bolt for the five hundredth time.