Torque and Chrome

If you overtorque an engine bolt, what will happen if?

Just as an example, say the manual says to torque a bolt going into the head at 30lb, but you mistakenly over-torque it to 45lb(assume that the bolt doesnt snap and no parts warp). If you go an loosen the overtorqued bolt completely, then torque it down to spec (30lb), is there a chance that the bolt will no longer hold at the specified setting because it has been "stretched" or "overtorqued"? Or, if it is overtorqued, is there a way that you can get a false read? For example, say when u went to retorque the overtorqued bolt, the torque wrench showed the correct 30lb, but due to it being "stretched, its only holding at 25lb or 30lb?

Public Comments

1. It would probably be suggestable to replace an overtorqued bolt. Just be glad it didn't snap off!!
2. depends on the location of the bolt you are torquing... in the example you give with the head... the compression placed on the gasket then backed of could result in leaks... also the need for expansion when hot... it is far more risky to "under torque" than over torque... it is always best to use a "quality" made tool when dealing with engine parts
3. I think it would depend on what size and hardness the bolt is and what it is holding down. If you easily achieved the over torque, then it may not have stretched. If you can loosen it and easily achieve the correct torque, I'd say your ok. If you tyr to torque it and it feels like you are tightening a bolt into mush, replace the bolt. If all else fails just replace the bolt if you are that worried about it.