A4SLINECAB

Hi everyone,
I have a 2016 S5 B8.5 with 70,000 km/ 43,600 miles and wanted to share what sort of issues I recently experienced, my diagnosis, and what I'm planning to repair.
I would love to get a 2nd opinion on whether this is how you would tackle the problem or if this is what you would repair based on those symptoms.

- While driving, heard squealing noise. I pulled over, popped the hood open, listened to the engine, and heard a loud rattling noise
- A few days later, after a 20min drive, low coolant light came up, stopped, popped the hood open and coolant was flying all over the engine, impossible to locate the source, the whole front engine was wet, the radiator was wet, pipes, wires everything was wet/soaked. Topped up coolant to the MAX level to drive back home and by the time I got back home, low coolant light was back on, and coolant level was way below MIN level.
- At home, trying to find the leak, I noticed the water pump pulley moving side to side off its axis. Also when it moves the rattling noise seem to amplify.

I made a short 43s video broken down into 3 short clips of the 3 instances above so you can hear the rattling noise and see the coolant spraying all over the place.

My Diagnosis: I think the water pump failed causing the pulley to move sideways (what we see in the video). When the pulley moves sideways it creates a gap between the pulley and the water pump from which high-pressure coolant leaks from, which would explain why it's flying over all over the place in a mist form.
See the red arrow in the below screenshot, in this video a guy demonstrates how the new water pump has no play while the old one has a lot of play. This is where I think the high-pressure coolant is leaking from, what do you guys think?



What I'm planning to repair:
Water pump + new water pump pulley (sold separately)
Preventately replace thermostat since it's just right next to the water pump.
Wondering if I should also replace the PCV valve?

Then in the front of the engine, I'm thinking of replacing supercharger/accessory belts,tensioners and idlers.

Any thoughts on my diagnosis and repairs? Would you do the PCV valve too? Anything you would replace I haven't mentioned? Or am I dead wrong on my diagnosis?

Thanks in advance

A4SLINECAB

Well I thought I'd give an update in case someone comes across this post with similar symptoms

I was right on the money, it was the water pump and was also right about the point of failure located in the bearings




On the other side, the water pump and thermostat seals look alright, doesn't look like it leaked through here. (replacing both anyway)