I have had this issue for the longest time since putting in a new radiator. The passenger side fan intermittently rubs on the oil pipe going to the radiator just in front of the shroud.

It doesn't look like it rubs when the engine is cold and spinning the fans, but when it heats up it soemhow maneuvers itself backward to bang on it. The fan spins straight and balanced. It's not wobbly when it turns on and shuts off.

Any thoughts? Could this be related to possibly having the radiator hoses pushed too far on the connections to the radiator causing it to contract when it gets hot?

 

that hose is probably the AC line and the line has gotten bent.
Carefully bend it back towards the engine to give about 1/2 to 1 in. clearance

 

Good point! Is it bendable by hand?

 

Fixed it. Thanks!