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  #1  
Old 02-16-2006, 09:34 AM
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rod bearing nuts

Just reinstalled the crankshaft after rear main seal replacement. Everything looked too good & all specs well within for a 290,000 engine. Just one thing that left me a little apprehensive. When torqueing the rod nuts, the secondary 90 degree torque after the initial 40-50 nm seemed too easy-no increasing resistance. The rod bolts measured above the minimum thickness, so I reused them, but figured this was the last time. Was I just feeling them stretch again? Will the head bolts feel this way when torqued? All I need is to throw a rod after all this time, money, & work spent. Thanks, Paul.

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Old 02-16-2006, 12:22 PM
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I've never had one of our diesels apart but I have gone through many other engine with "torque to yield" fasteners and they do feel weird sometimes during the final tightening. I wouldn't sweat it. You checked the thickness before and tightened them per spec which is all you needed to do, so you're good to go. Eric.
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Old 02-16-2006, 01:03 PM
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Thanks, I feel a lot better now! Paul.

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Old 02-16-2006, 01:25 PM
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Are you sure the rods get 2 x 90 deg after 40-50 Nm? This is almost as much as the head bolts. I'm not saying it's wrong, but I don't seem to remember that much. What size are those fasteners, I don't remember? Torque to yield on an alloy steel M8 is about 65 Nm, M10 about twice that.
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Old 02-16-2006, 02:18 PM
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DON'T reuse rod bolts.
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Old 02-16-2006, 02:55 PM
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The 617 Service Manual says you can reuse the rod bolts until they reach a minimum necked-down diameter of 8.0 mm.
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Old 02-16-2006, 03:40 PM
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just once

After the initial torque of 40-50nm, they are to be rotated 90-100 degrees just once, which I did. The necked down part of the bolts were above 8mm before starting. It was by the book, so I guess that's all I can do. Thanks again for the responses. Paul.

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Old 02-16-2006, 04:25 PM
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One rotation, that makes sense. And since the neck is 8, the thread must be M10. FWIW, I miked all of mine, they measured OK, and I reused them. 10K on it so far...

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