BenzWorld Junior Member
Date registered: Mar 2006
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Steel fasteners and Aluminum Parts
As part of a 560SL engine swap/restoration, I am dealing with a lot of steel fasteners going into aluminum castings and parts. Steel and aluminum love to gall. I'd love to hear some input as to the best procedures to be taken on disassembly to prevent galling on the threads.
Do I unstick a stuck bolt with a rattle gun, or just an ordinary wrench until the bolt releases? I have done the latter on several bolts which finally gave and removed with no damage. Do you recommend warming castings with a heat gun? Aluminum carries (conducts) heat way faster than steel and expands and contracts much more. Does this loosen or tighten the bolt in the hole? This issue really worries me. I surely would like to avoid repairing holes with heli-coils. Prevention is better.
The second thing will be on reassembly. Do I treat all fasteners with anti-seize? What type? The silver or the copper color? The MB service books give the torque values to use, but do not mention anti-seize or bolt lube requirements to get the proper torque value. What about use of the various thread locking fluids like Perma-Tex?
Any help (or past experience, good or bad) would be greatly appreciated.