Intermittent noise from engine bay

Hi,
I am getting a intermittent noise on my wifes '06 Mazda 5 Sport, the car develops a noise whilst driving.
It sounds like a motor has started running and after a couple of seconds you hear a click as it stops.
I am assuming the click is from a relay? the noise seems to be coming from under the hood infront of the drivers position.

Could be the fans for the cooling(radiator) coming on.

Sent from my XT1032 using Tapatalk

hi PK thanks for the responce. i have tested the cooling fan and
also switched off the heater fan and it's not them.

If it is more of a high pitched motor sound, its probably the power steering system, though I have never heard a clicking associated with that system engaging, or disengaging.

Is the AC compressor clutched on the 5? If so, it could be kicking on and off while using the defroster.

Air con isn't on when it happens. it is difficult to describe the noise. it is not high pitched it is more low pitched
woth the same sort of rumble like a hammer drill but sounding different. if you know what i mean.
also it also only happens when driving.

Wow. I hate chasing unknown noises.

My last car had a front wheel hub bearing that would make low pulsing noises until I'd touch the brakes. The brake would mute the sound.

I replaced the front CV drive shaft on the noise side of that car thinking that was the problem, but it wasn't.

I have spoken to a mechanic and he said it sounds like a servo
running or maybe a noisy solenoid.
He said the click definitely sounds like a relay operating.
at first i thought it was maybe the steering pump but not sure if 5he steering pump
or servi is electrical?
A week prior to the noise there was a loss of steering when the car was started up.
but after turning the engine off waiting a minute and restarting it was fine again.
so could it be the steering pump?

Yes, it is likely the power steering pump, which is an electric motor. At least on NA market 5s, not positive the Euro 5 is the same...

My 5's electric power steering pump makes nearly continuous whirring noises. Like a small hydraulic pump does. Which is exactly what the 5's steering pump is, an electric powered hydraulic pump.

The clicking may be the directional change of the hydraulics* from turning the wheel left and then right. It is fairly noticeable when I'm making minor steering corrections left and right when pulling into my garage. Of course, us Americans sit on the opposite side of the steering pump than you in the UK would, so you would hear more of it in action. That is assuming the pump is still inside the right side of the engine compartment.

*Either relay, hydraulic valving, or motor reversing, I'm not sure how the pump reverses oil flow on the 5.

EDIT: Knowing what I know about electro powered hydraulics. The 5's pump has reduced noise when it's not adding pressure to turn the wheel left or right. If the motor runs all the time, then a directional valve (or valves) allow the pump to go to a low pressure state when a valve isn't shifted to steer one direction or the other. This low pressure state is like an idle condition even though the rpms don't change on the motor of the pump from full pressure. What happens is the hydraulics are much quieter when they aren't under load.

With an older style engine driven pump via a serpentine belt, there is no electric pump noise to hear while the load increases or decreases.

Ok I have narrowed it right down to the DSC (if that's what it is called?), if I press the button under the steering column and turn off the DSC
I no longer get the noise. so could it be the DSC control board or as it sounds like a motor
running, would it more than likely be the electric ABS pump on its way out?

Interesting. I leave my traction control on and haven't noticed anything weird.

Maybe my car doesn't have what you have, if DSC is Dynamic Stability Control.

It certainly seems to be a problem with the DSC as I have now been driving the car with the DSC turned off and there has been no noise, but when it is switched back on the intermittent noise returns.

Question is where is the pump and control box located?

FiftySix you are not getting the noise as your car hasn't got the fault.