TIL most guys are torquing head bolts completely wrong on the first pass

I was helping a buddy out last month on a 6.7 Cummins rebuild over in Anaheim. He had his torque wrench set to the final spec and was just running them down in one go. I had to stop him and explain the torque to yield procedure... you gotta hit the lower number first, then angle it. He looked at me like I was speaking a different language. Thing is I did the same exact thing for like 5 years until a old timer at a shop in Santa Fe Springs pulled me aside. He showed me a cracked block from someone skipping that initial step. A torque wrench can be off by 20 percent when you're trying to hit a high number cold. Has anyone else run into guys who skip the step or just go straight to final torque?

2 comments

2 Comments

the_zara7d agoTop Commenter

My buddy Ryan out in Riverside almost toasted his 4BT swap last year doing the exact same thing. He had his torque wrench cranked to 120 ft lbs and was just hammering them down without any pass. I told him to back off and do the low torque first then angle it, but he got all defensive saying his buddy at a diesel shop does it that way. Then we pulled out the factory manual and he saw the two step procedure. The look on his face when he realized he'd been risking his whole build was priceless. He had to redo all 26 bolts and the block was fine luckily. Did you ever see that cracked block in person, or just the pictures?

the_jenny7d ago

@the_zara I swear some people think torque specs are just a suggestion, like speed limits on the highway. Ryan must have felt Real smart staring at that manual after bragging about his shop buddy's method. Good thing he caught it before he had to buy a new block, nothing like a cracked 4BT to ruin your whole month.