I've found this only works if you do a decent amount of damage. Just running around the corner isn't going to do it. Pop out and hit him a few times with ranged and then go back and bandage if needed. It's really easy to get him down to about 50% in the two minutes without getting hit much.

As a 65 hunter alt, I just sent in my pet, healed him, fired a few rounds, and brought back to the safety of the corner when he was getting low on health. I waited until he was all healed up and sent him back in.