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Just been down to Devon for the weekend to visit family there, and on the way back this evening, the car started making a low pitched humming noise, which I'm sure wasn't there on the journey down on Friday evening. It's difficult to describe, but it will still happen even when coasting with the engine switched off. Obviously that rules out the engine, as switching off made no difference at all. It kicks off at about 20mph. However the increase in road speed doesn't seem to increase the 'speed'* of the hum, which I find rather confusing. *can't think of the proper engineering / scientific term so that will have to do! The back axle is full (already checked that - I hate the smell of gear oil...), and hard cornering doesn't seem to increase the volume of the noise. The only thing I did find was that an exhaust joint is blowing slightly, but I can't see how it is connected. Any ideas what on earth it could be? It's driving me nuts, firstly as I can't identify it, and also because I know it has the potential to be expensive  Any tips / advice on how to identify the problem would be very much appreciated. |
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ChasR
RR Helper
motivation
Posts: 10,194
Club RR Member Number: 170
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Tech Qu - Strange noises.....ChasR
@chasr
Club Retro Rides Member 170
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If you've ruled out the wheel bearing and engine I would look to the propshaft and gearbox.
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First thing that sprang to my mind was propshaft bearing grumbling.
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Thanks guys! Someone on the VOC has also suggested the prop bearing. I'm just hoping it's not the axle or the gearbox as those have been rebuilt relatively recently by an old Volvo specialist so shouldn't be playing up.....
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B-8-D
Posted a lot
down to one car!!
Posts: 4,038
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prop bearing seems faverate paul..
si
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Now that I'm less tired and grumpy than I was last night....
When driving, power on / off seem to make no difference at all. The noise kicks in at 20mph, and whilst it increases in volume as the road speed increases, the noise still sounds the same.
Presumably then, I can safely discount the differential gears?
Hoping to get a new centre bearing delivered by tomorrow so I can deal with it that evening after work. Anything more major than that & I won't be able to sort it out myself.
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id say wheel bearing.... ive had that before on cars , and on some its not sped up , the hum stayed the same as it was just the noise of vibration from it
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Many thanks to all for the info / diagnostics  Forgot to say in my last post (browser crashed so had to re-write it) that this morning when driving off, I managed to provoke some driveline vibration that wasn't previously there, which was another reason that I believe that the centre bearing & it's rubber donut are guilty of crimes against my ear drums. Fingers crossed that this is indeed the case, as I don't have the equipment (or the necessary ability to use said equipment) to shim up the rear wheel bearings correctly  |
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Last Edit: Jul 6, 2009 16:41:20 GMT by Paul H
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Had the car jacked up last night, and could feel some roughness in the centre bearing. Bearing carrier doesn't look fab either. However I couldn't get the 2" nut on the propshaft undone, as I don't have a 2" spanner or an adjustable / mole wrench with big enough jaws. Nor can I find anywhere local that has one either.
Going to have another try tonight, this time with a hammer and cold chisel to knock it free, and / or one of those chain oil filter wrenches.
I am not a happy bunny, as if I can't get this sorted in time, no Retro Show for me.
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Nathan
Club Retro Rides Member
Posts: 5,626
Club RR Member Number: 1
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Tech Qu - Strange noises.....Nathan
@bgtmidget7476
Club Retro Rides Member 1
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Funny how just before a show our cars seem to just wanna die.
My fuel pump packed up last night so hopefully the new one arrives before saturday afternoon otherwise we are only taking 1 Car!
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Had a brainwave a moment, and just phoned up Latchmere Motor Spares (AKA Fred's Spares), whom I'd completely forgotten about (less than 10 mins from work too!), and they have in stock a hulking great adjustable spanner that opens to 2 5/8" so I may be in luck for getting it sorted tonight. Fingers crossed. Still going to get that chain wrench and chisel though...
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No luck I'm afraid. Spent all evening underneath, changing the bearing and its rubber carrier (definite play in the old bearing, & the carrier looked pretty tired and was likely to have been the original!) but it's made no difference. Tbh, all I can think of now is a wheel bearing / diff bearing. Very strange though, as everything pointed to the centre bearing. Oh well.....
Someone elsewhere mentioned engine & gearbox mounts, but the noise is still there, even when coasting in neutral with the engine off. Can an iffy engine / gearbox mount still do that?
Logically, it is therefore either a wheel bearing, or between the rear wheels and the output shaft in the gearbox. Whatever it is is constant, and road speed related, not engine related. Doesn't matter which gear is selected, nor whether in or out of overdrive - would that rule out the back of the gearbox / o/d?
Rear wheel bearings are an pain on Amazons as they need shimming, so that's not something I can do myself - ditto anything inside the axle. I'm also pretty skint at the moment, so probably won't be able to afford to get it sorted for a while. There is also the issue of who I can trust to do the job properly.
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Are we sure it's not the pinion bearing in the diff?
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Seth
South East
MorrisOxford TriumphMirald HillmanMinx BorgwardIsabellaCombi
Posts: 15,514
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Is it really bad? I'd be tempted to drive it until it gets worse and you know for sure what it is! A front bearing ought to be able to be detected by jacking the car and spinning each front wheel in turn. You sure its not something really simple like exhaust/similar touching the floor? Should have a spare seat Sunday morning if need be  |
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Follow your dreams or you might as well be a vegetable. |
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Are we sure it's not the pinion bearing in the diff? The diff / axle was 'rebuilt' a few years ago with a new CROWN wheel & pinion, but I'm not ruling out anything for various reasons..... Factory workshop manual section on the axle says it could be the pinion or diff bearings. Doesn't reckon wheel, driveshaft bearings or gears due to constant nature of the noise. Is it really bad? I'd be tempted to drive it until it gets worse and you know for sure what it is! A front bearing ought to be able to be detected by jacking the car and spinning each front wheel in turn. You sure its not something really simple like exhaust/similar touching the floor? Should have a spare seat Sunday morning if need be Kicks in at 20 mph, and still audible at 80 / 90. Exhaust looks clear. Also it has a degree of movement to swing slightly from side to side due to how it's hung, and cornering has no effect. Didn't check the front bearings - noise sounds very much as though from the middle or back of the car (but noises can travel...). Rear wheels turn freely & smoothly, but haven't had enough experience checking wheel bearings to know for sure. Cheers for the offer of a lift - will see how I feel. Also have the lurgy at the moment so feeling doubly grumpy! Thanks for all the advise - hopefully will get this sorted soon. |
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Last Edit: Jul 9, 2009 10:17:22 GMT by Paul H
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It couldn't be somthing like a loose bit of trim flapping in the breez and returning to position when you stop thus remaining undetected? Or is it just not that sort of noise!?! Just a thought! ant
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That sounds like a pinion bearing to me. Bumhats! |
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Have you had a look at the brakes, sounds silly i know, but i have had similar noises when a bit of stone/dirt gets stuck. Also cleaning the brakes out is a no cost option, and helps get rid of the dust |
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1993 Fiat Panda Selecta
2003 Vauxhall Combo 1.7DI van
2006 Mercedes Kompressor Evolution-S AMG SportCoupé
"You think you hate it now, wait til you drive it"
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;)Check the TYRES for bulges and "out of shapeness". I've been caught out a few times looking for wheel bearings, axle and gearbox bearings faults because of noise and vibration when all the time I should have been closely inspecting the TYRES! |
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kee
Posted a lot
Posts: 4,988
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but that wouldn't be a constant noise, wouldnt it get higher pitched as he drove faster?
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