Please help identify this noise! (vid inside)

[mechsman]

Hi all

I've got a potential issue on the sax. I'm getting a whirring noise from the engine bay somewhere and I'm trying to work out what it is. Vid here:

http://img.photobucket.com/albums/v426/goldtj/saxo/th_MOV_0065.jpg (http://smg.photobucket.com/albums/v426/goldtj/saxo/?action=view&current=MOV_0065.mp4)

The noise is a kind of grinding/whooo whooo noise and it occurs in neutral with the clutch up (as in the vid) and when driving in 1st and 2nd (disappears in 3rd). It also disappears when the clutch is pushed in and held. It seems to be related to engine revs as opposed to road speed.

Am I right in thinking this is the clutch release bearing dying? It's gone from no noise to this in 2 days (~200 miles) If it is the release bearing is it likely to die in short order and kill the clutch?

Thanks in advance

[Cam]

Sounds like the gearbox, them inner wings are rotten!

[mechsman]

What bit of the gear box chap? Nah, I had a look over the rust, it's only surface stuff at the moment.

[adamspencer]

i sometimes get a faint noise like this when driving from the drivers side under the bonnet. didnt think anything of it

[adamspencer]

is it just me or does it get louder when its near the alternator and the revs pick up? are the bearings in the alternator on their way out or something? just bouncing ideas around

[mechsman]

See, that's it, the noise isn't very loud at idle, but you really hear it when accelerating through 1st and 2nd. I think the whine from the alternator side is just the aux belt under tension. I had it tightened recently as it was squealling like a pig in the wet when under load.

My reasoning behind it being the clutch release bearing is the fact that it goes away completely when the clutch pedal is depressed and held down.

[adamspencer]

as far as ive heard, a clutch release bearing would make a higher pitched sound, and would do it whatever gear you're in. And even if it is the bearing, you could go another 5k miles before it goes completely leaving you with no clutch. I'd recheck your tensioning on the alternator belt first cos if its not right it may cause the whining

[mechsman]

Ok, I'll double check the belt today. If it is the belt, why would the noise go when the clutch is held in?

[adamspencer]

it may be because there is less strain on the engine as it doesnt have to spin the clutch assembly within the gearbox. And when you put the clutch in do you rev it again or leave it at idle?

[mechsman]

Right, checked the belt tension this morning, it doesn't appear to be overtight. Also, the car is now making the noise when the clutch is held in and the car is coasting.

Adam, if I'm down changing the engine normally gets a throttle blip to help match the revs to the box, if i'm changing up then I allow the revs to drop fairly low before slotting the next gear in. In the vid above, it was in neutral with the clutch up and I was revving it by hand to try and demonstrate the noise as it seemed louder just above idle revs.

[adamspencer]

i would suspect alternator then as opposed to clutch release bearing as the noise is directly linked to revs of the engine, as opposed to what gear/road speed you are using/doing. I dont see how you'd test it without getting another alternator though which may end up costly, and if it isnt the alternator it'll be a waste of money. I wonder if you could take the alternator off and somehow spin it by hand and see if it makes the noise?

[SnakeVTR]

Could be the cambelt bearing's whining i.e water pump and tensioner bearings :y:

[SnakeVTR]

Also to rule out the alternator remove the alternator belt and run it with out the belt on, if its still there then it isnt that, you be fine to run the car for a few minutes with no alternator :y:

[mechsman]

Right all, popped round the garage this evening and let them have a look at it. Bloke took it out for a quick test drive. Turns out that the noise is coming from the box end, but it isn't the release bearing, it's the box itself! A bearing on the input shaft somewhere is dying, so, new box time. When I said I'd driven it 200 odd miles home like that he said that I was lucky the box hadn't grenaded and locked the engine/wheels up at speed!

Going for either another 1.4 box or a vtr box (longer final drive and long 5th for relaxed motorway driving). Interesting fact I learnt whilst looking for boxes, the 1.4 box and the diesel box have exactly the same ratios and final drive!

[SnakeVTR]

if it was the input shaft then the noise would go when the clutch is pressed, didnt you say it started doing it with the pedal pressed aswell :afro:

[stevo67]

Don`t rule out a worn bottom pulley(crank pulley)

[mechsman]

if it was the input shaft then the noise would go when the clutch is pressed, didnt you say it started doing it with the pedal pressed aswell :afro:

Yeah I did, but the car was coasting at the time, so the input shaft would still have been spinning if the box was in gear (but the pedal held down) wouldn't it?

Don`t rule out a worn bottom pulley(crank pulley)

Would a worn bottom pulley present the same symptoms? I would have thought that would be more of a knocking noise than a bearing rumble/grinding noise?

[stevo67]

No mate you`d get a whinning/squealing noise.

[mechsman]

OK cheers, this was definately more of a rumble/grinding noise than a squeal/whine