[stonestick]

Hi! Has anyone seen something like this?

Car's done 185 000km, I've driven it the last 45 000km. This issue definitely wasn't present in the beginning, I noticed it in the recent months. Thumping sound is quite intense and it sounds like it's coming from the engine compartment. It is only present during a cold start. After revs drop, everything is back to normal. No complaints other than that.

 

[budleach]

What kind of exhaust system do you have?

 

[vista88]

I've heard that sort of noise before when the EVAP system carbon scrubber gets clogged. The fuel tank doesn't vent properly and it puts excess vacuum on the plastic fuel tank.
Next time you do a cold start loosen the gas cap first.

 

[stonestick]

I've heard that sort of noise before when the EVAP system carbon scrubber gets clogged. The fuel tank doesn't vent properly and it puts excess vacuum on the plastic fuel tank.
Next time you do a cold start loosen the gas cap first.

Wow, didn't expect to get an actual diagnose (fingers crossed) in less than a day.. I did 2 cold starts with the gas cap off - no thumping - and then one with the cap on - thumping. Thank you so much!

By carbon scrubber you mean #1 in this schematic? Carbon filter with fittings. 2016 Volvo S60 | the Official Volvo Car USA Parts & Accessories Online Store

 

[vista88]

I don't see the small charcoal scrubber in that diagram. It is bullet shapped and sits behind the larger rectangular canister.