pully assembly keeps coming loose

Just finished timing belt change on my 1987 928 S4 everything went well, did an around the block run, checked then 40 mile shake down cruise, again ok, then drove up over Mingus mountain and back still good.

2 days later I recharged AC went to start it and the accessory belt pulley spun loose, got my mechanic friend re did everything torqued to 217 ft# started and same problem.

Any Ideas? HELP
Chris Mullen

Does the A/C compressor turn relatively freely with the drive belt off?

When retorquing the 217 ft. lb. crank bolt, is crank being locked in place with locking tool?

Is there any oil or grease on threads of crank or crank bolt?

217 ft. lbs is usually enough to lock stuff down, so that's definitely odd.

Have not had time to check how free the AC pulley turns next on list to check,
Yes I put the locking tool in place before torquing the bolt
no sign of oil or grease on bolt etc
dont have time to play with until saturday any other Ideas would be helpful, Im also going to get a different touque wrench just in case ther is something wrong with my friends' wrench