Wife fired up the car to head to work today and I heard a pretty loud rhythmic knocking/rattle coming from the engine, matched RPMs. Although it was loud outside, I could barely hear anything odd inside the car. Popped the hood and felt around, I felt nothing on either side of the engine (felt just below the valve covers), but do feel the pulse when I put my hand on the t-stat housing.

Just wanted to check in if based on that very basic diagnostic you'd come to the same conclusion as me that the water pump's bearings are shot. Unfortunately I forgot to check for play before heading to work myself, but the pulley's axial movement was definitely not perfect watching it spin. We're at 151k and I have no records of it ever being replaced so it's been on my to-do list anyways.

What else should I replace while I'm in there? I'm thinking hoses, belts, and any particular pulleys? Or the tensioner? DIY I just watched showed a pipe behind the t-stat as well (not the internal transfer pipe). I'd like to order parts today so I definitely get them by this weekend. Also WP brand recommendations would be appreciated.

Thanks!

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'08 X5 4.8i - 196k
'15 i3 REX - 95k - Blown AC compressor

'98 323is - 170k - Garaged
'94 325i - 208k - Sold