Mystery noise
Q My Ford Fiesta 1.0 Ecoboost is making a droning noise that is audible above 5mph, but does not increase with speed. I can best describe the noise as very similar to an overtightened plain drivebelt (non-toothed or grooved).
The main dealer can find nothing untoward on this just-out-of-warranty vehicle. However, I have just discovered that an inner CV gaiter is leaking grease, but I do not know how long it has been doing this. There is also play apparent on this CV joint when I turn one part of the driveshaft, where the leaking gaiter is, against the other. The passenger side driveshaft has no play whatsoever. Is this the source of the noise? David Herbert A You will appreciate that diagnosing a noise without the benefit of hearing it can be difficult, so I will list various possibilities which will hopefully direct you to the right area.
As the noise does not increase with speed, but is reliant on the vehicle moving, I would not expect it to be hub bearingrelated, but it remains a possibility. This would normally be one of the more common sources of such a noise.
Although you have discovered a slight movement between the driveshaft and CV joint, this would not be the typical noise I would expect from this area. However, as you have discovered a leaking CV gaiter, I would take the opportunity to replace the gaiter and grease the joint.
As you describe the sound as being like an overtight belt, if your Fiesta has a manual gearbox I would check that the noise is still present with the engine switched off and the gearbox in neutral. Find a safe area of road where it is possible to disengage the gears and roll the vehicle down the road with the engine off and the ignition switch in the ‘On’ position. As the noise occurs above 5mph, this does not have to be done at any great speed, but will help to isolate the area the noise is coming from. Care must be taken when doing this as the power steering and servo braking will not be operative. If the noise is not present when the engine has been stopped, this will point to it being emitted by the engine, whereas if the noise is still present it will indicate a driveline issue.
Another possibility is that the problem is tyre noise. By swapping the front and rear tyres, this may alter, or even silence, the noise.