C4 Spacetourer 2.0 BlueHDI - clicking on right side of engine, whirring at accessory belt

[Nick_UK]

Hi friends,
I recently bought a beautiful C4 Spacetourer 2019 with 35,000 miles. This is the 2.0L BlueHDI diesel (DW10FC) which doesn't have the dreaded timing chain issues.

I noticed two engine anomalies - shown in video here https://photos.app.goo.gl/2dSuymwFbhasgejU7
- clicking at the right side of the engine (always) - I have not heard this in any other C4 diesel engine. Can someone help me identify the part in the attached photo, which is where the clicking is coming from?
- a rough idle which could be heard on the exhaust as well as under the bonnet, with the belt tensioner rocking - this only happened today after a cold start/short drive.

I have this booked in with Citroen dealer for a major service in 10 days (this will also include checking the basics), so I'm just looking for ideas on what this could be so I can look out for other symptoms and brief the mechanic.

Other items to note
- Car has 37 MPG in city and 50 MPG on highway so I think engine is functioning OK overall.
- No errors/service lights yet, but when I bought the car, the OBD port cover was still open. This could be from MOT or maybe they cleared codes...
- when I first test drove the car, there was exhaust smell coming from the aircon system; this has since cleared.
- it takes approx 1.5-2 seconds for the engine to start from cranking, this seems to be on the longer side in my experience. And start/stop is not working, but presumably both issues are down to the AGM battery being too old (12.3 V charge max)

Thanks for any advice and ideas.

[merlin667]

The part you labeled is the vacuum pump for brake assist and other things requiring low pressure. maybe there is a valve or pressure switch which you hear, but nothing to be concerned off.
I also noticed a rough cold start idle on mine with almost the same engine. maybe this is caused by a high load of the alternator after start (glow plugs, electrical heater..) combined with the cold engine.

An OBD Check is done at every service at the dealer so an open cover doesnt mean anything, just forgot to close it.

Did you compare it with any other 2.0Blue HDI? this is a totally different engine than the smaller ones so a different sound / ilde is normal.

[Nick_UK]

Just to follow up, the engine got quieter after an oil change/full service.
Also, the rough idle disappeared after the DPF and sensor were replaced under recall.

[wurlycorner]

Glad to hear all sorted - even better if under warranty/recall!