crank arm coming lose

[number7s]

my left crank are on the cannondale f5 keeps coming loose, ive tried loctite on the bolt, the bottom bracket is square taper, i cleaned all the dirt and grease but after about a mile the thing it completely loose, i cant figure out why, Bent arm?

[Seat Sniffer]

is it visibly bent? I use a set of bent arms but they're not too bad. If you have a steel square taper and an alloy crankarm that was overtightened at one point, it may have loosened up and now bottoms out on the spindle. Or the spindle could be worn. Try turning it one flat forward or back and mounting it there? I usually tighten to 40-45nm.

[number7s]

thanks ill try that