Tracking down a grumble....

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PiLsY.
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Tracking down a grumble....

Post by PiLsY. » Thu Mar 08, 2007 9:59 am

Hoping people can throw me some suggestions here. I've got an intermittent grumble coming from somewhere. It's hard to track down exactly where from in the car, from the drivers seat it sounds like the drivers rear, from passenger seat, passenger rear. It comes and goes as well, when accelerating its smooth, when braking its smooth, normal cruising (most noticeably below 40) and if you play with the accelerator a little you can make it happen. Does it all on its own sometimes, but it can be forced to happen.

Its fairly loud, but not incredibly loud (people don't turn and look!), the car doesn't bobble or weave at all. It gets no worse at different speeds. You can feel the vibration through the gear lever but it doesn't seem to come from the gearbox itself.

I've checked all the wheels, they don't wobble on the bearings at all. Everything seems taught on the suspension front and rear (bushes etc).

I'm thinking along these lines...

Wobbly / sticky caliper / Warped disc or,
Exhaust rattling on mounting or
Loose gearbox / clutch bolt (but I thought this would manifest constantly and get worse with speed).


Now it doesn't feel unsafe or unsteady at all and its getting no worse with use. Should point out this a new car (to me anyway) and was stood for 6 months before I got it. Rear arm bearings were done 20k ago, so hopefully not those!. I also managed to drive it home from buying it (albeit slowly) with a loose rear passenger side wheel, which I believe is what's caused the problem (had nothing to tighten the bolts back up with!). The wheel was tight at first, and must have loosened itself off when I was doing a bit of citroebics in a car park halfway home to try and soften the suspension up a bit (now fine btw!). Within about 3 or 4 miles I could feel a vibration (infact I thought I had a flat) and then crept home the remaining 75 miles.

Any ideas, tests or suggestions welcomed!

Cheers guys,

Matt.

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Post by jolly_green_giant » Thu Mar 08, 2007 11:09 am

Hi, glad to see your having lots of fun with my old car, I bet the wheel brace has slipped down inside the cover in the boot from the right hand cubby hole.
It doesn't sound like a break disk to me and I haven't had any problems with the transmission on that car (always seemed rock solid to me). If it's the exhaust try pushing the tail pipe around and see if you can make it happen, also have a look around under the car to see if there are any clean patches where it has been rubbing. I had this problem on the BX some lovely person wrote off with his audi.

JGG

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Post by PiLsY. » Thu Mar 08, 2007 11:21 am

Cheers for the reply Tom. Yep, loving the car...the suspensions all starting to free up again and its getting smoother. May swap the 16v spheres onto my GTi though - its a tad bumpy with 5 adults in the car :).

I agree about the transmission, it feels really positive, no slips or anything. Im just wondering if my stupidity in not noticing the wheel was loose has rattled a bolt loose somewhere. My feeling though is that its something to do with the disc / caliper on the passenger rear or exhaust rattle. Will check the wheel brace on my lunch hour, cheers for the suggestion.

Matt.

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Post by BX Bandit » Thu Mar 08, 2007 7:25 pm

I'm not sure what model you have but I had a 'rumble' on my TD, it turned out to be the intermediate bearing on the drivers side drive shaft...was not obvious that this bearing was the culprit (it was hard to pinpoint the noise/rumble) but after removal it was clearly knackered...you may get away with feeling the play in the bearing just by having a good...er....feel'n'push...but removal may be necessary to make sure..good luck and keep us posted!!
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Post by PiLsY. » Thu Mar 08, 2007 9:07 pm

Sorry should've said its a 92 TZD :).

I'll have a grope around and see if I can get anything to move :shock:. The main problem, as you mentioned, is I can't figure out exactly where its coming from. Every time I turn my head towards it, it seems to be coming from somewhere else. It feels like something wobbling against its mounting rather than a grumbling bearing or anything.

My stuff to do list so far is :

LHM, Oil, Coolant, Filters
Adjust rear height corrector level - its way too low at the moment on normal ride height
Check spheres / oil struts
Find this sodding noise!
Fit fogs, swap indicator stalk/fix self cancelling, fix rear heated screen
Fix leak in front door window seal (I can hear it dripping into the door skin and the water in the bottom slosh about when i brake!)

Not too bad, hope to get most of it done this weekend, weather permitting. Need to get the tracking done, but that's pointless until the suspension is spot on. It's currently way out though.

Matt.

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Post by Oscar » Fri Mar 09, 2007 8:55 am

I dunno - sounds like driving with my wife if you ask me....
(Red BX 1.7TZD ("Well, it is a style icon" - Tom Sheppard)) "Was", Tom, "was"

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Post by BX Bandit » Fri Mar 09, 2007 7:33 pm

Oscar wrote:I dunno - sounds like driving with my wife if you ask me....
:lol: Easily pin pointed tho'!!!

Worn bearings tend to run hot..so run a few miles on the motorway and have a wee feel of the bearing to see if it's hot...and I mean ouch! hot so be careful..
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Post by PiLsY. » Sat Mar 10, 2007 11:12 am

Well its not the spare wheel. I took it out and tightened the cage up with a big washer stack under the nut in the boot so it wasnt going anywhere.

Out of paranoia I checked the wheel nuts when I got out the car this morning from a quick 4 mile run and the front drivers side wheel nuts were hot - I can't remember if I've ever noticed this before on a car...is this normal? Maybe heat from the bearing going through the nuts?

Found a small puddle (just wet road, not an actual puddle) of lhm on the road under the accumulator sphere area. Power steering felt a little heavy this morning too. Hmm. Off to investigate.

Matt.

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Post by BX Bandit » Sat Mar 10, 2007 7:07 pm

Well, if only one side is hot (or markedly hotter than the other) then you could have a siezed brake caliper/siezed hand brake cable or a knackered wheel bearing...
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Post by jolly_green_giant » Sat Mar 10, 2007 7:31 pm

Hi, hot nuts is perfectly normal just after stopping a car. The bolts have direct thermal contact with the break discs which is where the kinetic energy of the vehicle is dumped when using the breaks. As a rough idea assuming no radiaton or conduction of energy and a mass of 8Kg of iron, when stopping from 60mph the iron will reach a temperature of approximately 100C above its previous running temperature. I know this isn't exactly real life assuming no radiation or conduction however it does give an idea. If you want to check dragging breaks jack it up and give the wheel a spin, drag from the drive shafts will stop it spinning fairly quickly but it should still move fairly freely. To check a wheel bearing, jack it up and wobble the wheel from side to side feeling for any free play. There should be none that you can detect. If there is any the MOT which is coming up will detect it anyway.

Sorry to hear about the other problems you have, it's amazing what 6 months standing does to a car.

JGG

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Wheel bearings.

Post by Geoffrey Gould » Sat Mar 10, 2007 8:23 pm

Hello I am not sure about always being able to feel play in a noisy bearing, I have had them without any detectable play but were really grumbly. When removed were found to be dry, with hardened grease that wasnt doing a great deal. I know in theory the bearing getting hot should melt the grease and provide some kind of lubrication but it dosnt seem to work that way.
The rear wheel bearings on mine had a bit of a grumble so I removed the grease cap and used a mixture of gear oil and grease injected it with a seringe as far into the bearing as I could while turning the wheel, result silence. I mention this because I couldnt work out where the noise was coming from.
Cheers.
Geoff.
1991 BX 1-7 td Auto.


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Post by PiLsY. » Sat Mar 10, 2007 9:48 pm

I think its the passenger side drive shaft. There was a tiny bit of rotational movement each way, with a clunk as it "engaged". Drivers side felt solid, no play at all. Also spotted the rubber bush at the back of the passenger wishbone is perished. If you listen next to the wheel with the engine idling you can hear the knock ever so quietly. If I'm right the passenger side driveshaft turns very slowly at idle, so this would support the shaft being knackered? Just been on a 30 mile round trip, the knocking is only there below 40 and only when coming off the accelerator and then cruising.

Rear height corrector is pretty solid. There's a bit of movement off the height lever, but most of it is just the metal rods and hinge mechanism bending rather than the corrector moving.

All bearings are tight and all wheels spin, but rub slightly.

Power steering is still heavyish, but the trackings out which won't help plus the LHM is minging.

Things are on hold now for a couple of weeks until I can afford new bits and pieces. Anyone here fancy changing a height corrector and driveshaft in a couple of weekends time with me for some beers and cash? Have a haynes, naff all tools, a couple of axle stands and two left hands if thats any help? :D

Matt.

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Post by docchevron » Sun Mar 11, 2007 1:11 am

Well, Billy's getting very nifty with the spanners these days, and he's in Chester too!

I dont plan to be up that way for a good couple of months, sometime early June, but I've no doubt someone "oop narf" will be able to to the required bits, it's all pretty straight forward stuff..

Cheers
Chris G
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Far too many BX's, a bus, an ambulance a few trucks, not enough time and never enough cash...