whistling noise under the bonnet.

[vr1066]

Hi all,

After spending the day polishing my VW VR6 mk3 and joking with my mate that it will end up in the garage with my luck, guess what? When I started her up that night I got a whistling noise from under the bonnet. I am a complete novice when it comes to anything other that checking oil and water (so probably less than a novice) but now very interested in cars and how they work.

When I lifted the bonnet to "have a look" it seemed as thought the noise is coming the belts to the outer left of the engine. The noise is not constant, it does change pitch but not at any particular time. The noise is intermittent but extremely annoying and obviously can’t be good for the car.

I'm going to take it to the garage but is there any advice anyone can give me with regards to this? Am I looking at an expensive job from the short list of possible problems or is there something I can try my-self before going to the garage?

Any help will be much appreciated.

[waynne]

Whistling noises generally come from leaking air hoses, vacuum lines. Look all over the engine at each rubber cable/pipe join and check for a split or loose connection. Also check that the air box is sealed shut tight - loosen the locks off it then retighten to make sure.

Are you sure its not a gearbox whine? You positive its a whistle?

[Freddie]

I'd put money on the noise coming from the alternator.

Does the noise go after the car is warmed up?

I know that on my car, there is a nipple on the alternator which apparently comes out of the factory with a plastic coating.. Once this wears off it is just metal rubbing against metal and makes a whiney whistling noise when the car is cold but seems to disappear when it warms up..

[vr1066]

Thanks for the feed back guys.

Someone had mentioned the alternator but the noise doesn't always begin at start up. There seems to be no consistency to noise, the noise will start sitting idle or while driving.

I think the burst pipe(s) of some kind may be the issue, although at times it does sound like more than one whistle. You know like 2 or 3 at slightly different times. It's sound like wind blowing thru something.

I'll try and have a look for cracked pipes, although I'm night shift all week end, and let you guys know how I get on.

Once again thanks very much the advice.

[waynne]

Washing up liquid mixed with water - spread this over the rubber pipes and you will clearly see any air loss as bubbles!!!!

[vr1066]

Absolute genius mate.

Wouldn't have though to do that. Probably would have went round burning my hands on stuff :P

Thanks, I'll be back with an update.

[vr1066]

Hi,

Sorry I ain't been back with and update, I’ve been night shift so I don't really do anything except sleep.

Anyways....

I tried your suggestion of checking the pipes under the bonnet by wetting them with soapy water. None of them seemed to be cracked or burst.

Then at the week end then I drove up to the north or Scotland, about a 200mile round trip. On arriving home I noticed the noise had gone!?

Since then there has been no more annoying noise's from under the bonnet.

I'm still going to have the car checked over this weekend coming so hopefully if there are any problems they are found.


Thanks for all your help and advice. I've got a few more questions for you guys but I post them separately.

Once again, cheers.

[waynne]

Look forward to tackling question 2. (I forgot to mention that Soapy water is known to fix most engine problems )