Raleigh71

I have a traditional cotterless crank on my road bike. Everything is campy (Campagnolo Record crank, chainrings and spindle, nothing sealed, no bearing cages; no cassette; just free ball bearings and a spindle, crank arms, screws, and spindle covers). The left pedal crank arm keeps getting loose every few hundred miles.

I removed any grease I could from the screw threads, and crank arm, and moderately forcefully tap the crank arm onto the spindle with a rubber mallet or hammer and block of wood. I don't have a torque wrench, but I make it pretty tight but not so tight as to strip the threads. The washer inside the crank arm is OK looking, and I just added a toothed lock washer.

I've never thought you needed lock-tite on crank arm screws.

Anything I'm doing wrong?

tommy gayle

with the parts that are coming from over seas the quality of bolts and screws the part in question may be as much as .002 to .001 out of proper size and the heat (and I know it is not much) could allow the tolerance to be out enough to allow the screw or the bolt to back out
lock tite or fingernail polish to help it along.
now with that said I am not a bike mech but I have a background in metal and fasteners
good luck

DMF 

I seriously doubt that quality is an issue with Campagnolo Record components.

Most likely cause is improper installation (i.e. insufficient torque on the bolt), followed by deformation of the crank socket upon loosening. Unfortunately, the arm is ruined. You'll need to replace it. This time use a torque wrench.

G piny parnas

shim it with a coke can and use 2 flat washers and use a different crank bolt-- check the length--
no locktite.