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03-04-2021, 02:28 PM | #23 |
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the shop may not have messed up during install but I said as soon as you posted this. The Rod threads were tripped. NO way around it. What caused it could be a mirred of things but more likley is defect rod or bad install at some point if you are not the original owner who so to say po didn't have them done and a rod was over tq'd witha factory bolt.
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03-04-2021, 02:42 PM | #24 | |
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I'm really curious to hear of this issue. I didn't find any discussion on stripped threads so I have no idea of how often it happens. My hope is the shop helps me out somehow. The motor was running fine before it was opened up, so there must be some value to it. What would it be worth with a bad rod? |
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03-04-2021, 02:57 PM | #25 | |
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03-04-2021, 03:05 PM | #26 | ||
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This car was meticulously maintained its entire life. There were zero indications that anything was wrong with my car before I changed bearings, even the Blackstone report was clean as a whistle. Zero issues with my BE Bearing installation. The extra heat theory reeks like sweaty ass, to me. I seriously doubt that your rod was damaged prior, because I would imagine it would have windowed your block.
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03-04-2021, 04:11 PM | #28 | |
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Like is the rod all discolored? I guess the type of question I would have: What could explain stripping the threads of a connecting rod? Previously yielded conn rod threads due to overheating of the rod bearing? (is the rod discolored?) Poor manufacturing of that 1 rod by BMW? Previous owner yielded the rod threads? (Are there any clues that these aren't the original bearing shells, or that the crankcase has been previously invaded?) Reusing Torque to Yield bolts and that torquing process to check clearances? (Could this over stress the rod threads?) There are more questions for sure... but which of these seems the most likely, so far? ...and the thing that lit up my Spidey Senses was the claim that "the crank is out of round, so you need a new engine anyway..." In my skeptic's mind, it was translated to "Nothing to see here folks, keep moving along, pay no attention to the stripped threads..." And maybe they didn't do anything wrong, but the BE bolts are not 1 time use like the BMW bolts are, so it seems like they'd be better off using the BE bolts to check clearances in the future.
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03-04-2021, 04:21 PM | #29 |
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...sorry, if turns out that reusing one time use BMW bolts and re-torqueing them using the BMW torque procedure can cause a thread failure, I'm not sure I'd be comfortable replacing just the one rod assembly.
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03-04-2021, 04:27 PM | #30 | ||
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I inspected the bolts and they all looked perfect. Not a trace of thread material. We spent some time discussing the missing thread material and even went into the rod itself with a scope. You could see the missing section of threads and a very small fragment that was peeling away from the rod, but nothing that accounted for what was missing. Because the bolts have a narrow shoulder compared to the threaded section, any thread material will be left behind when the bolt goes through the intact threads on the rod. To be clear, the stripped area is about a half inch down into the rod's threaded section. I guess the shop was trying to pick out those lose threads this afternoon with a little progress. They also managed to get the APR bolt to catch enough intact threads to torque down to 50 ft-lbs, but they could tell it wasn't a fully captured bolt. We don't even want to start the motor up for fear of that rod end pulling loose. |
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03-04-2021, 04:33 PM | #31 | |
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My latest plan is to have Dinan build one of their 4.2l motors using mine as the core. It's more expensive than the cheapest option for sure but a 0mile motor has its appeal. I feel somewhat reluctant to throw a new motor into an old chassis though despite it being in nice shape |
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03-04-2021, 04:42 PM | #33 | |||
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03-04-2021, 04:48 PM | #34 | |
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03-04-2021, 04:55 PM | #35 |
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I would be very surprised if the threads were stripped prior to disassembly.
I would love to be able to take a look at this engine for myself. Cheers,
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03-04-2021, 04:57 PM | #36 | |
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If you forget to do any maintenance and ignore the idiot lights, technically this lack of maintenance can cause rods to bend and cranks to be damaged... Bolts being stripped? I've got nothing... But I am just being a cheeky twat.
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03-04-2021, 05:12 PM | #37 |
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Another question to ask them:
"Hypothetically, If I could actually prove there is nothing wrong with the strength of the rod, by an outside material analysis lab, and if got one or more engineering materials experts that calculated that your process, using used BMW bolts and the BMW torquing procedure, caused the rod threads to be over stressed, would you be willing to take responsibility?"
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03-04-2021, 05:18 PM | #38 |
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What shop was it?
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03-04-2021, 05:25 PM | #40 | |
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Seems like you are learning something completely useless, if you are going to do the final install with a different bolt and a different torque.
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03-04-2021, 06:41 PM | #41 |
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I'm thinking there's a 5% chance the shop is innocent. Just such an odd situation to happen without outside interference. I would bet there was foreign material on the threads - ripped the thread when they went to torque. Makes sense to me as the first couple threads are apparently spotless
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03-04-2021, 06:42 PM | #42 | ||
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03-04-2021, 06:51 PM | #43 | |
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03-04-2021, 07:35 PM | #44 | ||
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