On 01/02/2010 06:57 AM, Tegger wrote:
> jim > wrote in news:Kf-
> :
>
>
>>>
>>
>> [much to the delight of "crv guy" no doubt] i actually disregard factory
>> oil pan plug torque. 45N.m is very high for something with a soft
>> aluminum crush washer under it. i use ~30N.m and have never had a
>> thread strip, nor a plug loosen or leak. replicate at your own risk.
>>
>
>
>
> I've used the factory washer and torque setting of 33 ft/lbs (45 Nm) for
> close to ten years now. The six years prior to that I mostly used a fiber
> washer and 20 ft/lbs.
>
> My suspicion is that oil pan thread stripping is due to /severe/
> overtightening, not adherence to the factory setting.
in my opinion, 45 N.m is over-tightening. two reasons:
1. the oil pan is a relatively soft material - it has to be to be formed
out of a single piece of steel like that. torque near yield, plus
thermal cycling loads - too close for my comfort.
2. the annealed aluminum washer starts out pretty much as soft as the
fiber washer - it seals by deformation filling all the crevices, not by
compression as such.
bottom line - once it's deformed enough to seal, it doesn't need to be
deformed any more. torque similar to the fiber washer is sufficient.
>
> I also suspect the factory beefed up the threads on pans made after 1991 by
> using a slightly heavier gauge of steel for the thread insert.
i'm not sure most of them even have a thread insert. if they did, it
could indeed be a stronger material and higher torque, but that's not
the point - the point is that torque only needs to be sufficient to
cause washer deformation sufficient to seal - and to provide sufficient
friction to prevent loosening. anything over that is excess. honda
have specified a mechanical load torque on a non-mechanical load fastener.