Main bearing cap bolt question
#1
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I'm rebuilding the AJ133 (5.0 NA) from my range rover. Probably didn't need to pull the main bearings, but was chasing down some aluminum in the oil and wanted to at least look at the bearings. They're fine. Before I did that, as a way of making sure I could "undo" what I was doing, I read that the main bearing bolts can be re-used at least once, similar to the flex plate bolts. Can anyone confirm? Any experience with this?
I've seen that as a general rule, any bolt with a NM torque then an angle torque (57 NM plus 70 degrees for example) is TTY thus one-time-use.
Thanks in advance!
I've seen that as a general rule, any bolt with a NM torque then an angle torque (57 NM plus 70 degrees for example) is TTY thus one-time-use.
Thanks in advance!
#2
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chp, looking through my reference that is specific to the 5.0L engines, there is a reference to the bolts only being used a max of 3 times, with a punch dimple being added every time the bolt is tightened to record the number of tightenings.
Now, with this being said, being a person that had to make their living based on how things got torqued, I would be questioning this "3 times use" and would probably be getting new bolts just to be safe. You are correct in that when you tighten something to yield, you are taking all the stretch out of the bolt and that doing that process again will take you beyond the yield point of the bolt, resulting in its failure. The indication that you would see if you are going too far with the bolt is a slight necking of the bolt. So, you could always "sacrifice" one bolt, tighten it like it says and then immediately remove it. If you see the neck of the bolt thinning, then re-use of the bolt should not be done as you have gone beyond yield. IF the neck is still even, then you would have been good and you can use the other bolts.
Now, with this being said, being a person that had to make their living based on how things got torqued, I would be questioning this "3 times use" and would probably be getting new bolts just to be safe. You are correct in that when you tighten something to yield, you are taking all the stretch out of the bolt and that doing that process again will take you beyond the yield point of the bolt, resulting in its failure. The indication that you would see if you are going too far with the bolt is a slight necking of the bolt. So, you could always "sacrifice" one bolt, tighten it like it says and then immediately remove it. If you see the neck of the bolt thinning, then re-use of the bolt should not be done as you have gone beyond yield. IF the neck is still even, then you would have been good and you can use the other bolts.
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