Name that noise

[DustyGeek]

We have a 2022 Entegra Accolade 37k on the S2RV chassis. When at highway speeds I hear a faint “whirring” motor type noise for about 20 seconds every 5 minutes or so.

* It’s quiet but audible to me. Unfortunately my wife says she can’t hear it.

* I’ve never heard it at lower speeds or when stopped.

* I’m pretty sure it’s not the air system as that makes more of a clacka-clacka noise and I can’t hear that any longer once we get rolling

* This is about the pitch of the whirring of the blade on a big cabinet-style table saw

* it sounds to me like it’s coming from right behind and to my right, but can say positively as I’m driving so can’t exactly get up and move around to better identify the location.

I’m fairly sure it’s a normal noise as it has happened since we got the rig, just would like to know what it is as I’ve identified every other sound (e.g., turbo, fan, air compressor) that occurs when underway.

Any ideas?

[DonkeyFluffer]

It's not the cooling fan from the radiator kicking on at about 200°?

Mine is not very faint, but the frequency can be similar

[DustyGeek]

Good question, but definitely not the cooling fan. When that turns on, there’s no mistaking the jet engine trying to escape the hood.

Much like to cooling fan, however, this noise does indeed seem to be either event driven (when X happens it turns on) or time driven (every Y minutes).

[Jeepin Jason]

Does it happen when you are stationary? Ask because we have some noise with the cabinetry near the sink rubbing against something that creates a similar noise while driving. We also have a load crackling noise that was the cab separating but that came mostly from the left of the driver. We started to hear some noise from the top of the bunk as well.

[Murff]

Sounds like a there may be an electric cooling fan. Once the engine hits a certain temperature, the fan will engage. Once cooling is achieved, it will stop until the temp rises again.


Murff

[RVermont]

Is it possibly the turbo? I notice mine at high speeds but it is fairly consistent when I am driving doesn’t cycle on and off as you describe. But it comes on when I put the pedal down and I am already driving 60+.

[DustyGeek]

All good questions.

Definitely not the turbo. Much like the cooling fan, that has a very unique sound which was one of the first things I noticed.

I’ve never noticed it when at slow speed or stopped, only fairly consistent highway speeds (55 or higher). Not saying it doesn’t occur, just never heard it.

It does sound fan, turbine or motor-like. As I said above, the tone/pitch/speed reminds me of the sound of the whir of the blade in a cabinet table saw.

I suspect it’s something unique to the Freightliner S2 or diesel coaches in general.