I have a very well maintained/looked after Ford Escort 1.6L.
I've noticed that going from around 30 to 60 MPH there is a humming noise that sounds like it's coming from the engine somewhere. It also seems fairly intermittent. It's not particularly loud. It's as loud as the engine but a different tone, so you can hear it together with the engine noise.
Any ideas what this might be. The Cars done 36'000 and was recently serviced (Oil, fuel filter, plugs, oil filter) Belts were done 2 years ago due to the age of it.
Thanks