Help!
My 1991 Cavalier SRi has developed a humming noise at 50mph+
To begin with it sounded like an exhaust hole, but a journey up on ramps revealed no leaks or holes.
Then i began some tests, putting the clutch in didn't get rid of the noise, so i think this removes transmission as a cause.
Any ideas?
Thanks
BCZ
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Does the noise increase going around bends? If so, sounds like you've got a shot rear wheel bearing.
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Haven't really noticed that DD, seems relatively constant, but it does seem to come and go if the car is bouncing along an uneven surface.
Why do you suggest its the rear too?
cheers
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Why do you suggest its the rear too?
Only reason I suggested the rear bearings was because I've previously owned various Vauxhalls, including two mk3 Cavaliers, both for four years each and never had a front wheel bearing fail, nor knew of anyone else had one fail either. However I have had rear wheel bearings fail on my '82 Mk1 Astra, '87 Mk2 Cavalier and '91 Cav, and they all hummed at speeds over 40mph, and the humm was even noisier when going around bends. eg If it were the off-side bearing, the humming noise was louder on LH bends as the Off-side wheel was the loaded wheel. IIRC, from either '92 or '93 Vauxhall ditched taper roller bearings in the rears for fixed bearings. I never had a wheel bearing fail on my '93 Cav.
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Cool, I'm off to buy some new bearings, if they are fairly cheap i'll buy and change the full set and see if this helps. Is it a dealer only part do you know?
BCZ
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wo'ah, slow down a minute BCZ. Don't go buying new bearings on what I've suggested. First you need to diagnose if they are actually worn. Only real way to do that is to strip down the rear hub assembly and inspect the bearings for wear. Normally the needles or shells are pitted and can be seen quite easily once cleaned up. You might only have to replace the one side.
No they aren't a dealer own part. You should be able to get from any motor factor. Haven't bought any for quite some time, but the last set I bought were QH (Quinton Hazels) and were around £25 a side, IIRC.
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Steady on.
Dave's splendid theory is a possible explanation, but you can't assume that this is the cause. If it's the bearings, then there would be bearing rumble or play noticeable when the wheel's jacked up. You don't want to jump in and change good bearings.
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Thanks for your help so far
I won't rush to halfords in my lunch hour then. I'm actually doing a part time car mechanics course at the moment,
so i'll be able to strip them down on thursday night and have a good look at them - must consult Uncle Haynes first too.
BCZ
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it does seem to come and go if the car is bouncing along an uneven surface.
Sounds like something is making contact when the suspension compresses, maybe a loose exhaust mounting causing the exhaust pipe to contact the body and transmit vibration...? Or a loose bush somewhere?
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BCZ
What tyres are on the car?
My Vectra had a 'failed rear wheel bearing' sound, diagnosed by all my pals, which turned out to be the tyres - Goodyear Eagle Tourings (NCT3's). Only started when they were part worn. Does the noise appear to be related to road surface - I note your comments about bumpy roads?
As DD rightly says, don't just get wheel bearings on the off-chance - they are not something that commonly fails these days. You need to be much more sure of the diagnosis, and then only replace the failed bearing, if that what it actually is.
Regards
John S
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Thanks John,
Actually the car did have tyres redone just after i bought it, but the tyres were very similar to the ones they replaced, and the hum wasn't so obvious prior to the tyre change you're right.
Road surface doesn't seem to be a huge difference maker, hence i'd sort of ruled this out, in my head at least.
If this is the case though i suppose i'm stuck with it until the tyres are worn.
Cheers
BCZ
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You could try swapping the wheels around - ie take the rear nearside and putting it on the front offside etc. If the noise moves then it is the tyre. If it stays then you're probably looking at a bearing.
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True, although annoyingly I've got special tyres upfront on the driving wheels, the rears are a completely different tread pattern.
Thanks anyway
BCZ
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Ok time for an update.
The cav went on a long run yesterday - nearly 300 miles.
and the noise has developed, extending into motorways speeds too.
However the noise seems to disappear if i go round a left handed bend, then as soon as i come back straight or go round a right the noise is back annoying me again.
I think this sort of adds to the argument of the wheel bearing theory. From this info can anyone identify which bearing could be the cause?
Do they have to be replaced in pairs too?
many thanks
BCZ
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BCZ,
Yep, sounds like a wheel bearing. I have a noisy one on my Xantia at the moment, exhibiting the same smyptoms. Left hand bend quiet indicates LH bearing (it is unloaded whilst cornering). You need to ride alternately in the front and back to try and decide whether its front or rear. If you can't tell you might have to wait until nit get worse, so you can identify it by sound, or by some play or roughness when turning the wheel off the ground.
Richard
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I agree with Richard.
From what you're saying it does sound like the LH bearing. As I mentioned earlier, from experience, more than likely the rear bearing. A simple check is to jack up and secure the front of the car with axle stands. Grab road wheel top and bottom and see if there is any play when you rock it. Find someone to apply the foot brake and repeat. If there was play there with the brakes off, but disapears when brakes are applied, then this would indicate a worn bearing. Repeat proceedure for the rear wheels. However if the bearing is only just starting to wear, any play may be hard to detect without a stripdown. The rear hub bearings are easier to inspect than the fronts, so that's where I would personally start. Don't forget to arm yourself with a Haynes manual as you'll need to torque up the rear bearings on refitting.
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Thanks for your help today.
Consultation with Dr Haynes tonight.
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