"John Burns" > wrote in message
...
>> Less sure about this. The bolts must surely still be in the area of
>> Hooke's
>> law, otherwise mere thermal expansion and contraction of the [aluminium -
>> high cte] block would damage the [steel - low cte] bolts.
>
> I was under the impression that they were torqued past the bolt's
> elastic limit. Isn't that why they're single use?
>

Your're right, but they only go just into the plastic deformation area -
this is to allow for less accurate [factory] assembly and for relaxation of
the gasket after running.

It might be worth investigating whether the bolts in the failed area can be
replaced with non stretched ones.

OTOH I definitely follow the advice that if the oil leak is small and you
are not losing compression or water, then just top up.