Engine Bay Noise

[TranceTrousers]

I've had an unusual intermittent sound come from the engine bay of my 57 plate Aygo Black recently.

It's like a high pitched whirring sound, which has only happened twice so far, but both within the last week or so. It starts when I turn the engine on, but as I drive off it subsides after about 10 - 20 seconds and after that the car drives and sounds as it should.

The odd thing is that it doesn't happen every time, or even every time I start the engime from cold.

I'm a bit concerned about this, so any help or suggestions as to what might be going on would be most welcome. The car was given a major service in May this year.

For a while before this started I also noticed an intermittent squeaking sound too. I don't know if that's relevant or not but I thought I'd mention it!

[Raistlin]

Have you checked your water pump ?

[TranceTrousers]

Thanks for your reply. I wouldn't even know where the water pump is or what it looks like lol. Do you think that could be the problem?

[Unklian]

If you have no mechanical knowledge......

It maybe that you have only just noticed your air-conditioning compressor working.
It also starts the cooling fan on the radiator.

Tomorrow, make sure your air-conditioning is off.

Start the Aygo.

Let it sit for a few seconds.

Turn on the heater fan......just on "1" will do.

Listen carefully......

Press the air-con switch.
Bit of a clunk then whirring fan noises?

Is that the noise?

It will stop after 30 seconds to a minute, then after a pause, start again.

It will keep going on / off while the air-con is in use.
If that IS the noise, your Aygo is behaving perfectly normally.

Ian.

[TranceTrousers]

Thanks for that suggestion and information, but I already knew what the A/C sounds like and it's definitely not that.

It made the noise again this morning when I started the car, but after I'd driven it a short distance the noise disappeared and the car has been fine all day since. It only seems to happen sometimes and only when the engine is cold.

Any other ideas?

[Unklian]

Turn on the ignition.

Turn on the heated rear screen.

Turn on the headlights.

Wait about 10 seconds.

Now start your car.

Is it a squealing sound?

Is it louder / worse than before.

If it is, you may have a loose alternator belt?

Ian.

[TranceTrousers]

Hello again, I know it's been a while but I thought I'd just report back. I didn't get a chance to try out your last recommendations as I haven't heard any more unusual sounds coming from under the bonnet since I last posted (26th August)! The car has started normally and run just fine ever since, so hopefully whatever it was has righted itself.

[petesellit]

I get this more in winter months when there maybe more moisture dew in the air & the belts slip for a while at first.

[TranceTrousers]

I hadn't even considered that. It never happened last year though (I've only had the car since May 2014).

Even though I've not heard that noise again, I'm sure the engine sounds a bit different. It's hard to describe really, just a bit more of a higher pitched whiney sound to it. Not constantly though. And I can still hear that squeaking sometimes too. I just hope everything's ok and it's not the calm before the storm.

[TranceTrousers]

The whining sound has started again. The first time was a few days ago, and then tonight it did it again as I was leaving work. I started the car and it made a dreadful whining sound, but I carried on, and as I went to pull away out of the gate the engine cut out and the engine warning light came on. I started the car again and so did the whining, but after a short distance it subsided and I made my way home without any further problems.

I'm thinking it's either the water pump or the alternator that's at fault, and I'm leaning towards the alternator at the moment. The reason being this topic here http://www.toyotaownersclub.com/forums/topic/139831-whining-from-engine/

The symptoms the OP had with her car are exactly the same as the ones I'm having with mine, and she fixed hers with a new alternator. I haven't had any electrical problems or trouble with the Battery yet though, wouldn't that be happening too if there was something wrong with the alternator?

I think I read somewhere that the alternator is easy to swap out if the front (bumper?) of the car is removed?

[petesellit]

Further to my post, My alternater

I get this more in winter months when there maybe more moisture dew in the air & the belts slip for a while at first.

Gurther to my post, My alternator did pack up all of a sudden, since Its been replaced along with the belt no noises etc. Maybe best to have belt checked before Winter sets in? cheaper than replacement £250