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I was torquing injector hold-downs dry for 8 years until a guy in Abilene handed me his wrench
For the longest time I just ran them down to spec dry, figured clean threads were enough, and I never had a comeback so I thought I was fine. Then in Abilene this older fella watched me do a set on a 5.9 and asked if I was oiling the bolts, and when I said no he about fell over. He said dry torque reads 20 to 30 percent low on friction, which means I was probably under-tightening every single one. Do you all lube your hold-down bolts or am I the only one who missed this? and if you do, what are you using, motor oil or something else?
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tessap972d ago
The part that gets me is how many guys check their torque wrench against a buddy's and call it good, not realizing the real problem is friction on the threads, not the wrench. Even two calibrated wrenches will read different if one guy oils and the other runs dry, so the tool was never the issue. That's why some manuals actually list a wet spec and a dry spec separately, and if you use the dry number on oiled threads you can stretch the bolt or pull the threads right out of the hole. I switched to a light coat of clean motor oil on the threads and under the head, and I back it off about 15 percent from the dry spec unless the book gives me a wet number. Once you start doing it that way you can feel the difference in how smooth the bolt turns too, and that alone tells you the clamp load is way more even across all six.
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