UKC

I try not to ask many non climbing questions but I'm a bit stumped.

Vauxhall Astra 2009 petrol, non turbo, manual gears.
I've noticed the last few weeks a whiring noise when the car is moving, seems to increase with speed, not the revs, BUT it stops when in neutral 😐 I was thinking wheel bearing but sadly no. I don't think its CV joints as there's no noise on forward/backwards/turning.
Its currently at 140,000 miles and I service it regularly as the manual advises. I changed transmission fluid at 90,000 - could this be low? I've not noticed any fluid/ oil leaks.
😐

In reply to Pesda potato:

I had something maybe similar once. It was much worse in some gears than others and the whirring in the bad gears got progressively worse over a few weeks. Garage in France hadn't a clue and wanted a fortune to take the gearbox apart to look, so I called Graham the mechanic under Wicker arches, learned that the gearbox wasn't repairable, then drove it from the Pyrenees to Sheffield in third gear and got a recon gearbox fitted for much less.

In reply to Pesda potato:

I've had two occasions like this... first was an issue with the clutch plate and the second was the thrust bearing. Both needed a new clutch.

In reply to Pesda potato:

Could be the synchromesh on the gearbox.

In reply to Pesda potato:

If its connected to road speed rather than engine speed then its not a clutch or transmission fault.
You say its not a wheel bearing but they can often whine long before there's any detectable play. I had one whining for over 20,000 miles before I got round to changing it, there was still no play in it, just a bit of roughness when rotated.
Have you checked the back wheels as well?

In reply to pec:
Damn I was hoping someone wouldn't say gearbox...
I'll research thrust bearing and clutch plate thanks

In reply to Pesda potato:

what ive found so far doesnt point to clutch / thrust bearing as that would only make a noise when pressing the clutch pedal to engage / disengage the plates.
any other thoughts?

In reply to Pesda potato:

Clutch release bearings can go the other way too, only quiet under load but that wouldn't really fit with it not whirring in neutral.

My first suspicion would be a gearbox bearing or gearbox oil level.

Are your tyres evenly worn out of curiosity? The rubber bushes in lower arms can be quite sophisticated (though I've no idea about the Astra specifically), deforming (and failing) unevenly under different loads, it could be your tracking changes under acceleration scrubbing a tyre.
jk

In reply to Pesda potato:

Perhaps its inner CV joint related on one of your drive/prop shafts that's not on the steering end?

It doesn't sound too gearbox related, is it there when you cycle through all gears?

In reply to Pesda potato:






Does braking have any effect on the noise, other than by changing road speed?

In reply to Pesda potato:
Sounds like a wheel bearing to me, they hum or whine for years until the start rumbling. Try lifting the car and then gripping hold of the wheels with both hands and giving them a good wobble. Obviously you should make sure the car is properly supported on axle stands and keep your limbs out from under the car when doing this.

Edit,
Also, you say you checked the CV joints (I guess you did this by driving around a carpark slowly at full lock in every direction), could it be the inside CV joints rather than an outer joint? I'm still thinking it will be a wheel bearing TBH.

Is one of the driveshafts longer than the other? Does it have an intermediate bearing/joint/damper? They can occasionally wear out.

Did the noise start suddenly, or gradually increase over time?

Why do you say it's not a wheel bearing?

Have you ruled out the brakes?

Can you guess if the noise is front/back/L/R?

In reply to Pesda potato:

Some good replies here

Makes the noise in any gear
It can't be wheel bearing because it goes away when I press the clutch in/ put it in neutral!

I'll try investigating the inner cv joints next

Tyre wear is even ish yes

In reply to Pesda potato:
Try bleeding the clutch release slave cylinder/hydraulics in case there is air in the system resulting in the clutch riding the bearing. If it was the clutch release bearing going you would normally only hear it going when you depress the clutch because otherwise it just sits there doing nothing.
Either that or it could be a gearbox input shaft bearing. My focus has a worn input shaft bearing that grumbles (and has done for at least 5 years) but you only really hear it when the car is idling in neutral because this is the only time when this part of the gearbox is turning and the engine noise is quiet enough, although you say it's quiet in neutral.

Inner CV joints are a bit of a pain to play with and test, if you lift one drive wheel, put the car in gear and try turning the wheel by hand you may be able to feel play in different parts of the system. If you do need to pull the joint you may lose all your gearbox fluid (you do on many fords).

In reply to Pesda potato:


Engine is ruled out. What you have said above means that from the wheels to the output shaft of the gearbox is ruled out. If the noise goes away with the clutch out but it in neutral then it's unlikely to be the clutch release bearing.

Therefore the only thing really left is the input shaft (and associated bearings etc) of the gearbox.

Is there a difference between coasting in the highest gear (low loading on the gears) or strong acceleration or overrun in lower gears (high gear loading)?

Most likely is that the bearing has started to fret in the housing of the gearbox (likely aluminium). Not familiar with your car, but can be a known problem on some vehicles.

In reply to Pesda potato:

I had something similar a few years back with my Ford Focus. Ford dealer claimed it was the wheel bearing and replaced that, but the problem still persisted. Took to a local garage who fixed it. Turns out it was the alternator bearing.

I'm no expert, but the symptoms you described were pretty much identical to mine.

In reply to Neil Henson:
ok alternator bearing and input shaft thats two other useful ideas to look in to thanks

edit - just thought about it for a mo, could it be the alternator bearing? surely that would run even when the car was idling?

In reply to Pesda potato:

A couple of years ago I had a similar noise on my car which had identical symptoms. Took a couple of trips to the garage to solve but turned out to be just a metal plate which protects the brake disk which had been bent slightly when a tyre was changed and had started rubbing. Might be worth checking?

Phil

In reply to Pesda potato:
No that would be a constant noise, this goes when its in neutral

In reply to Pesda potato:


Depends how thorough you've been with your testing. Alternator load varies with engine speed (and other parameters), if you've only had the engine at idle when in neutral (normal use) the alternator may be basically unloaded and any bearing issue masked.

Another belt related possibility is a soft engine mount allowing moving auxiliary engine parts to rub when the drivetrain is under load. I've had this with an older car that had a viscous coupled fan on the front of the engine, it ticked against the radiator shroud on over-run. The Astra to be fair has a different set-up but it'll still have exposed belts.
jk

In reply to Pesda potato:

Mine was similar which is what rang a bell. The noise became louder as speed increased but as soon as you depressed the clutch to change gear or approaching a junction the noise stopped only to reappear when back in gear. I just remember considering similar options to those suggested here and being relieved that it was a simple fix before agreeing to spectulative repairs to try to fix it.

Phil

In reply to Pesda potato:

Thanks for your suggestions, all address much appreciated. I'll get under the car this weekend and investigate further.

In reply to Pesda potato:

Give changing the tran fluid a go. or at least make sure you have the correct level.

In reply to Pesda potato:

So what's the conclusion? Did you ever find the source of the noise?

In reply to Pesda potato:

Is it your girlfriend in the passenger seat?

In reply to Orgsm:

He said whirring, not whining!

In reply to Pesda potato:

I'm no expert but suspect your Astra might be fitted with the same General Motors M32 gearbox as my Alfa 159 - if so they are well known to be made of chocolate. Bearing failure, which manifests as a noise similar to the one you mention, seems to be a fairly common occurence. a quick google of M32 gearbox problems will tell you far more than I ever could. Good luck!

In reply to Pesda potato:

The best thing to do would be to ask on an Astra forum, but now you've asked here we need to know the answer .
My opinion - if it goes away in neutral then that points to something on the engine-side of the gearbox, but I guess it could be anywhere if it's due to load applied to the road side of the gearbox when it's in gear i.e. wheel bearing makes no noise until it's being driven by the engine.
Does the noise change under acceleration/deceleration?

In reply to Pesda potato:

I've not found out yet, also asked on my usual Astra forum too, going to investigate further this week.
Yes makes the noise on accel/decel under engine power
Everything works fine so I'm not overly worried.

My Astra doesn't have the gammy m32 gearbox thankfully