Re: Aluminum Oil Pan Bolt Torque

Posted by Bob J On 2023/2/4 17:44:22
Torque is dependant on the fastener, not the material that is being fastened. That was worked out by the engineers that specified the parts for the engine. So, if it is a steel 5/16-18 or 5/16-24 bolt/nut, it will be 15-18 ft/lbs. 1/4-20 or 1/4-28 it will be 8-9 ft/lbs. I doubt it would be larger, but if 3/8-16 or 3/8-24 it will be 25-30 ft/lbs.
Things change only when the fastener's material changes. For instance the bolt that attaches the battery cable to the starter is a 3/8-16, but the stud is copper, much softer than grade 5 steel bolts so the torque drops to 6-7 ft/lbs. Hope this helps.
The most important thing to check when attaching any cover such as an oil pan, valve cover etc. that is stamped from aluminum or sheet steel is to use a straight edge and a feeler gauge to make absolutely sure the parts are still as flat as possible on the sealing edge. Someone in the past that is not as conscientious as yourself will likely have over torqued the fasteners and caused the gasket to crush too far and then make the seam a series of spline curves between bolt holes making it very hard to seal. Some simple checks and a bit of work with body hammers and dollies will save you from this happening.
Good luck!
Bob J.
P.S. Oh as a rule, start in the middle of the part and tighten toward the ends, my mentor said to do it like you spread butter on toast!

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