Thanks Tortuga for the part number. I had tried a different version of this a few months back, but ordered ones that were too stiff so they actually transmitted a fair amount of vibration, esp from the oil filter housing.
Anyway, here is a picture of what the old power steering resevoir mounts looked like. Seems like the rubber they used just cannot stand up to the heat in the engine bay. At a buck or so each, can replace these every year if need be.
I had a very similar part under the air filter mount on my old diesel benz and I learned to add a drop of blue thread locker on the mount threads, the same vibration that makes the noise loosens the mounts too. Drove me crazy and went through several mounts until I had that moment of clarity.
That seems like a good solution but there is the problem that me and some other board members are running into. I put very sturdy 30mm bolts, washers, and rubber gaskets and am getting a bad vibration problem that is very audible in the car. I'm not sure why some get it and some don't?
I pulled the oil filter housing off and these mounts appear to be holding up just fine - no compression or cracking so far. As the OP noted, the bolt thru method OR an aftermarket mount that is too stiff, will transmit noise/vibration, esp from the oil filter housing. I don't think that means the bolt method won't work, but you may notice noise. These mounts seem to have enough flex that any noise/vibration isn't coming thru but also aren't falling apart (at least after a couple months). At < $8 for 4 of them certainly worth a shot.