[wmsimpson]

I'm rebuilding the engine on my 2000 Discovery II. The specs on the connecting rod bolts says to torque to 20 lb-ft, then turn through an additional 80 degrees. This suggests to me that these are "torque to yield" single use bolts. The RAVE manual does not specify they should be replaced, or at the very least the "*" symbol, indicating replacement, is not clearly displayed. There's something there, but it's not an "*".

Atlantic British does not carry these bolts. ARP does not make them. Rovers North charges an arm and a leg for them ($10 per bolt - and you need 16!). Rimmers is more reasonable ($4.50) for genuine LR bolts but I'll have to wait a week for them to get here.

So, do I need to replace these or not? If not, should I use the tightening instructions in the book, or tighten to a specific torque value? What might that value be?

Thanks!

 

[number9]

Humble

Viewed the manuals after reading. Having a great deal of work experience using technical manuals and fixing machines I would interpret as being OK to reuse the bolts. Probably being installed at a lower torque as compare to head bolts allows their reuse without failures. Sure we'd all feel better about reusing the bolts if LR had given a torque to spec rather angle. Don't know what size bolt used but the earlier engines used nuts torqued to 37 ftlb.

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[Jagfixer]

Anytime you have torque spec and a degree spec, bolts are a stretching bolt and should be replaced.

 

[helievacpilot]

Anytime you have torque spec and a degree spec, bolts are a stretching bolt and should be replaced.

x10!

 

[number9]

Decision?

Anytime you have torque spec and a degree spec, bolts are a stretching bolt and should be replaced.

No contest just another view.

The LR head bolts which need to be replaced and rod bolts are dissimilar and stretch differently hence the manual recommendations. Good information on fasteners is available for those interested and have the time to sort through it. Some mx manuals will give a spec to check bolt length prior to reusing to ensure it should be good to go. Since LR failed to include that info it might encourage me to replace them if available and within my budget.

From AC 43.13-1B:

NOTE: Many applications of bolts in aircraft/engines require stretch checks prior to reuse. This requirement is due primarily to bolt stretching caused by overtorquing.

If building an engine for somebody else on their dime or for pay offering some type of warranty I'd want to use new. Doing my own might reuse the bolts.

Bottom line......there's often more than one correct way to get the same results and even those can be disconcerting, e.g. the new new bolt failure.

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