Noise form the dash

[Ruff Nomads]

Hi Folks.
I have a 2006 Independence 8330 on a Ford. V10 Triton
I’ve developed a buzzing/whirring noise that seems oscillate in time with the engine. At first I thought belts, fan, pulleys etc. However I’ve sprayed silicone and checked the fan but in doing so I find I can’t trace the noise to the engine.
It appears to be coming from around or under the dash board/drivers foot well area within the cab.
The noise is the same as the engine interference you’d get on the radio but it’s not the speakers and the radio is off. That said with the radio on I do get that too.
Could this be a relay? If so which would be a likely candidate?
It’s annoying and driving me nuts.
Many thanks to you all for your help.

[Restorium]

Process of elimination would be to turn on and off each accessory while listening for a change in the sound.
I once had a brake vacuum booster make a strange sound. Put on the brakes and see if it changes.

[Ruff Nomads]

I’ve tried all sorts. Nothing changes the tone except the engine revs. Just like you’d hear over the radio with interference from the alternator. But it’s not that.

[Restorium]

Try moving the heater control switch to defrost and listen for the noise to change.

[GPappy]

Electric brake booster?

[Ruff Nomads]

I’ve only just learned about and got my head around this. It’s the best idea I’ve received.
There’s two systems.
HydroBOOST and HydroMAX. They work the same but HydroMAX has the electric back up pump.
My system is the HudroBOOST so no pump. However, I am convinced the sound is a bit of air in the system. I thought that could be the case before o learned about the brake assist but now I know it make sense.
The brake assist is at the highest point and pretty much where the sound is coming from.
If it doesn’t clear itself in the colder weather I’ll drain the system.
GPappy I you certainly in the right ball park.
Thanks

[THenne1713]

You do not mention if constant, with engine running at idle, or only when in gear, or only when traveling, Blower ON/ OFF, etc, but a few points: 1) Belts can make weird noises from rust that accumulates on pulleys during moist weather, but many of these will disappear after some miles, (but have also read ads that imply the quality of the serpentine can greatly affect belt noise?); 2) If the 2006 Ford still uses vacuum A/C/ Heat Controls can make strange noises if hoses leak; 3) I had a strange dash BUZZ (like a BEE or bad speedometer cable, but vehicle was electronic dash) that developed on a 94-Nissan Pickup at highway speeds when vehicle was 1-2yrs old that dealer could not find, and finally, after 6-12-months, I tightened (maybe only 1/32-1/8-turn) every nut/ screw on the engine side of the firewall, and it CURED the issue :-) 4) HAS A MUD-FLAP FOLDED BACK AGAINST A TIRE, (e.g. pressure-washer) NOW RUBBING ON TIRE WHEN MOVING? 5) Power steering fluid-level? LUCK TO YA

[Ruff Nomads]

Hi and thanks very much for taking the time with this.
I’ve just managed to track down the routes of the vacuum pipes, the construction the RV dash doesn’t make access easy in fact I think access was designed out.
I take the point of tightening things.
It’s my thinking at present that there is some air in the piwer steering system that’s worked it’s way to the HydroBoost. I’m convinced it’s either this or the vacuum theory but the noise doesn’t change when the heating controls are adjusted. It does however vary slightly when the brake is depressed.
The sound is a whirring/whooshing sound. Very front but varies in tone in time with the engine as one would hear from a belt. I have however ruled out belts as the noise is loudest in the footwell area.
Thanks again.

[THenne1713]

(Another thought, but NOT familiar w/ Class-A layout, mine being E450Sd), but last year, dealing with CHRYSLER VANS power steering pump noise on two separate vehicles, internet search revealed that they had a fine plastic filter screen in the PS Reservoir that filtered return fluid, AND that there was a (35,000-mile Change Reservoir and Fluid schedule), and BOTH vehicles had over 100k, AND new RESERVOIR ($23) W/ FLUID CLEARED the noise WITHOUT A PUMP CHANGE :-) :-) :-)

[Ruff Nomads]

That’s a new and interesting one. I wonder how I find out if the fords have the same thing?

[THenne1713]

That’s a new and interesting one. I wonder how I find out if the fords have the same thing?

I did see a POWER STEERING FILTER at Autozone that you can add to the return line, comes w/ hose clamps, (listed for Econoline) .. might be worth adding filter and changing fluid? (Looks like an add-on, and do not see similar at Rockauto

https://www.autozone.com/filters-and-pcv/power-steering-filter/duralast-power-steering-filter/13909_0_6138?fromString=search&make=Ford&model=&year=

[THenne1713]

Been 6+ months, Any luck?