Has he had the head/block checked for distortion? Everytime the head is removed it will distort due to the thermal stress thats built up when it is bolted to the block. Stuck thermostat? Blockage in the cooling system? What gasket is he using? Correct torque settings? Bolt holes in block cleaned out before inserting bolts?

Is the gasket going in the same place everytime?

I persume you mean it's a -31 actuator?