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Wrote off a hot torque check on head bolts for years, one guy in Omaha changed my mind
I always figured if I torqued the head bolts to spec on a 6.7 Cummins, running them again hot was just asking to stretch them. A guy at a shop in Omaha asked me how many comebacks I had on blown head gaskets and I had to admit it was 3 in 18 months. He walked me through re-torquing at operating temp in the factory sequence and backing off 10 ft lbs from the cold spec, and the next two builds held up past 60k miles with no seepage. Guess I was leaving a step on the table this whole time. Any of you run a hot re-torque on aluminum heads or is that pushing it too far?
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finley_wells669d ago
Man I learned that lesson the hard way on a 6.0 Powerstroke years back, blew the gaskets twice before an old timer told me the same thing about backing off the cold spec and running them again once shes up to temp. The trick is you gotta do it in the right sequence and dont just crank em down to full spec while shes hot, back it off that 10 ft lbs like your Omaha guy said or youll pull the threads right out of the block. On aluminum heads its a whole different ball game because the head grows way more than the iron block does when it heats up, so the hot re-torque actually matters even more on stuff like the 6.0 or a 4.6. Far as I know the aluminum can handle it fine as long as you let it cool all the way down before the final check and dont rush the cooldown with water or anything dumb. Three comebacks in 18 months is a painful way to learn it but at least you got it figured out now and those last two builds holding past 60k says it all.
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