Just wanted to share an experience:
Bought a used 2009 Honda Odyssey EXL in October 2018. Around February it started whining in a way that was related to the engine RPM. Started searching and found threads on power steering o-ring problems. Tried the inlet hose fix with an OEM orange/red o-ring. No change. The power steering got hard to turn at low engine speeds sometimes so I figured it was the pump. Replaced pump, reservoir, and inlet hose/flange/hose clamps, then new fluid. No change in whine, but steering got better. Started thinking it was the alternator. Was pricing alternators and read something useful. Went to Harbor Freight and bought a $4 mechanics stethoscope (has a stick on it). Tried probing around the engine bay and noticed that the sound was just as quiet on the PS pump as it was on the opposite side of the engine. Couldn’t be that. Tried the alternator. Sound was louder. Tried the two pulleys for the serpentine belt tensioner (had to put the stick carefully on the nuts they rotate on). So loud it hurts my ears! Took the serpentine belt off. Started grabbing pulleys and rocking them, spinning them. Two had slight play in them. The A/C compressor and the tensioner pulley with the 17mm bolt through it (I have J35A7 that has hydraulic tensioner, there is another similar Odyssey engine(J35A6) with a spring loaded tensioner). The pulley spun just fine and wasn’t making terrible noises. Put the stethoscope on the bolt and spun the pulley and heard a familiar whine/grind. Like metal on metal contact. Started the engine without the serpentine belt and it was quieter than it’s been in months. Went to O’Reilly auto (was within walking distance) and bought a tensioner assembly (Gates DriveAlign Belt Drive Tensioner part #39092 Line: GAT) and noticed that to get the bottom bolt off the tensioner I would have to take the wheel off and the wheel well. Could not reach the 12mm bolt from the top. Decided to only replace the pulley on the 17mm bolt where the tensioner pivots. Got it free with a 1/2” breaker bar and 1/2” drive 17mm (not enough space for my 1/2 to 3/8 adapter, had to buy a new socket). Was on there very tight. Slipped it off and got the new one on fairly easily. Noise is now gone.
Just wanted to share this experience with anyone searching for an answer to their whine noise. Buy the stethoscope. It is $4 and now is my favorite tool ever for finding this. Try starting without the belt on to see if the problem runs off that belt.
Can’t find any product that is just the single pulley, you have to buy the whole assembly unfortunately.