Class 185 odd noise.

[Philip]

I've noticed this high pitched turbo-like sound coming from either the exhaust or the engine on 185107 and 185128 very recently as well as a few others within the last month or so. The pitch of the noise goes higher as the engine revs harder. Often heard coming from the middle coach and only noticed it recently. Anyone know what's causing it and if it's a fault to be fixed? It makes them sound great when setting off!

 

[Pumbaa]

Possibly one of their methods of dealing with snow? I read somewhere they're re-diverting air intakes around the engines or refitting them somehow to avoid drawing in snow.

 

[Nym]

Sounds like a modification causing a change in exhaust or intake harmonics in the turbo, like pumbaa said.