[doctorbutcher]

Greetings!

As usual, I only post here when I require some help. My i30 has developed a weird noise. I haven't noticed this noise before, but I did this morning having driven to work and once in the works carpark driving slowly forward... i was doing maybe 2-3mph, largely just letting the clutch out and applying very slight pressure on the accelerator until the revs were around 1.5k; I could hear a sound that is best described as being like a helicopter rotor slowly spinning up as I moved. You know, that kind of 'swoosh, swoosh' noise they make.

The faster I got, the faster the spinning got until I could change up to 2nd gear and the noise vanished. It seems intermittant; the car didn't make the same noise as i pulled out of the car park to go home, and I purposely stopped and inched forward to the barrier to see if it would occur. It didn't.

It did however occur when I was pulling away from some traffic signals later in my journey, but vanished once I got out of first gear. It doesn't happen in reverse gear, or in higher gears. It only seems to occur at low speed/rpm and first gear, and then only on occasion. Car had its' 30k service in November along with first MOT; only issue was an advisory on my rear brake discs being slightly scored/pitted.

The car is a i30 diesel, 1.6 CRDi Active on 64 plate.

I know noises are pretty hard to pinpoint without hearing them, and given the intermittent nature a garage might struggle to find anything wrong. In any case, I'd welcome
any thoughts as to what may be causing the noise?

[John B]

Without hearing the noise, the way you describe it, it sounds like a brake pad not returning and slightly touching the Rotor brake disc or hand brake not releasing all the way maybe.

[eye30]

As you say a low speed in 1st, are there vehicles and or other objects so in a confined place or "tunnel"?

My thinking is noise feedback returning which would not be present if car in open space may be from exhaust, brakes, engine etc. The returning noise always sounds different and "odd".

[Dazzler]

Hi "doc",

Definitely sounds like something rubbing just slightly. Brakes is the most likely as others also suspect. I'd do a few laps of a carparks slowly and see if one wheel gets hotter to the touch than others..

[CraigB]

I'm thinking possible worn thrust bearing

[doctorbutcher]

Thanks all for your input... thrust bearing seems fine; no vibration through the pedal when i engage/disengage the clutch and no issue changing gear.

I came out this morning and driving out of the street it happened again, but sounded to be coming from the rear this time. Ive just been out with the car at lunchtime and did a couple of laps of the campus - i work at a university - and nothing. All good.

It is 12c currently though and dry; wet and 5c this morning so may just be a build up of crap getting cleared. Been a lot of grit put down on our roads the past few weeks so may e sime loss of lubrication as well.

I'll park tonight with the car in gear and handbrake off to see if the noise reappears tomorrow.

[sundiz]

I had similar noise caused by brakes. When I stopped I usually pushed the pedal with full force. Noise disappeared. Now with new rear rotors and pads the noise do not appear.

[doctorbutcher]

Right, now this is starting to really annoy me. Went to get my son from work, all good until I go into a roundabout in 2nd gear, as I accelerate out and up into third there is the noise again... once I've straightened up and shifted to 4th, the sound is gone and I accelerate normally. But for those few yards accelerating between 2nd and 3rd into 4th it sounded like accelerating on flat tyres. Noise came from the front.

Get the traffic lights about 300yds further up which are on red.  Stop, car in neutral, handbrake on. Green light, 1st gear and go, car accelerated fine all the way through the gears. Another set of lights and another roundabout; no issues. Nothing on the way back either.

Tyres feel firm to the press, and low pressure warning hasn't activated. Got me baffled, will get it into the garage.

[Dazzler]

Thanks for keeping us in the loop. Intermittent issues are always annoying. 

[eye30]

Have you checked exhaust is full tight on all joints.

Just a thought as the metal will expand when hot sealling joints.

[sundiz]

Might be good to check if there is any play on the bearings. Jack tyre up and grab tyre from top and bottom and try wiggle the tyre. It should feel almost solid. If there is play, then it might be the bearing. At the same time you can rotate the tyre and see if the brakepads make some noise.

[doctorbutcher]

Car is booked in with my garage for Monday morning to see if they can't find the cause, and if there is something wrong whether I might have a claim on the five year warranty. Right now it is a guessing game; I'll try and upload later a sound file with the noise it makes, assuming I can replicate it.

As an aside, and another potential cause, I noticed today when I was checking tyre pressures (all at 34) that the NSF tyre is wearing down quite quickly; the first cm or so of the outer tread is almost smooth and there is only maybe 2.5mm maybe 3mm of tread on the tyre. There is still some clearance from the top of the tread down to the indicator block, but it is marginal - maybe the thickness of a beer-mat - so I might need to throw new tyres on the front. The wear on the OSF doesn't seem as bad, but I like to change tyres in 2s/4s for consistency.

Fronts are Toyo Proxes CF2 and have done maybe 16k... is it possible that may be the cause of the noise, maybe the tyre is slipping due to being near-slick on the outside and a failing joint or bearing is adding to the wear?

I dunno...

[xiziz]

Sounds like break rubbing to me, like Sundiz said go out, up to 70/80kph and hit the brakes full force. Sound like there might be dirt stuck in the calipers.