Alternator bearings or maybe maybe something else?
When the car starts from cold (not when the engine is warm) it starts with this lovely high pitched squeel that goes up and down in pitch with the engine Revs. The noise will disappear after anywhere between one minute and five. I have this noise now on and off since 18 months, it started for the first time after heaving left the car for two weeks at Gatwick airport. It then disappeared for about a month, came back over winter, disappeared again for 3 or 4 months over summer and came back in September when the temperatures dropped. The annoying thing is that when I want a mechanic to listen to it, the engine needs to be cold therefore early in the morning and of course every time (4 or 5 times with three different mechanics) when I invited a mechanic to have a listen..... the noise wasn't there. What have we done? A month ago changed all the belts, idlers and tensioner, variator and water pump. Noise was still there. Noise pitch doesn't change when turning steering wheel so I think steering pump is still ok. Noise doesn't change pitch when using clutch or putting load on battery. Noise comes from the belt area I think bit it is very difficult to pinpoint. A warm start doesn't produce the noise. According to a Dutch garage it could be either alternator bearings or AC pump. But could also be exhaust manifold as the noise sounds a bit like a high pitched wind noise. Is there an easy way to find out (I suppose I have to do this myself as the noise only happens with me), without taking the aux belt off where the noise is coming from before committing to very costly repairs? Incidentally although I do not think this has anything to do with the noise, lately when I start the car the engine revs up higher and longer then before but this might also have something to do with the remap we did two weeks ago. All help is much appreciated!