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Mysterious knocking, any ideas!!

N

nick3814

New member
Hi, I know this isn't the best way of diagnosing a fault but I thought I would run it past you guys in case it seemed a familiar problem. My 1986 Lux has developed an irritating knocking noise, it doesn't do it all the time but it appears rotational, as you pull away the frequency increases with speed, sounds like it from the rear and makes like a clunking sound getting faster untill once your'e at about 40mph you cant hear it anymore. I've discovered if I swerve the car from side to side quickly it stops but can then start again soon afterwards, its gone a few days without doing it but then all of a sudden it returns, I'm thinking perhaps some wear and tear in the CV joints??

Any advice folks?

Cheers
 
CV's, possibly. Diagnose by driving 'round in a tight circle - the outside joint will work much harder than the inside one, so will make more noise if it is a CV which is up the spout.)

Loose brake pad?

Loose brake backing disk thingie (technical term that, please note!)?

Something in the diff? (Pricey!)


Oli.
 
wheel bearing maybe. I had loose wheel nuts once which sounded exactly like what you describe. Just check those first to eliminate them.

or it could be your `thingy' or `whatsit ' up the spout lol [:D]
wot part of Lundun are you from Oli ? I'm from Bethnal Green originally
 
a propa cockney then.
I moved out to Essex as a kid then down here to zummazet when in my teens. I'm a proper country lad now oooharrrr [;)]

Hate visiting London now to see my old man . I used to find it exciting but now it just seems dirty unfriendly and dangerous. Besides ,I miss my trees and other green stuff


 
Further to my original description, it was quiet this morning on the way to work, stopped at some lights, when I pulled away it started again, then the next time I pulled away it had stopped [:mad:]

Came home this afternoon, down a slight hill with no load on in second gear just coasting and it started again, knock knock knock, definately metal hitting metal, quite loud, I depressed the clutch and it stopped instantly, let the clutch out and it started again so I'm assuming its drive train related yet theres no problem in the way it handles or drives, just this damn noise [:(]

Any further ideas chaps [8|]
 
Nick,

Why not try investigating those ideas we have already had and let us know how you get on?


Oli.
 
Yeah I have done Oli, everything is ok, the driving round in circles doesn't shine any light on it either sometime it makes the noise sometimes it doesn't irrespective of left or right turns, wheels are tight brakes are fine, the one thing I have noticed is there is a bit of play in the drive shafts, grab hold of them and you can move them back and forth about 1/2 an inch from the wheel to the diff if you see what I mean, which if you do it had enough does knock a bit. I wouldn't bother me but its so damn loud when it starts!!
 
Exhausts sometimes have a habit of moving and start knocking against something under the car. I had this on a BMW once (front engine - rear drive like your 944), it took me ages and checked all the obvious things (CVs, strut top mounts, wheel bearings) before I found it was the exhaust knocking against the gearbox. It also only happened at certain times and not always when doing the same thing like pulling away.
 
have you had it on a ramp and checked if the exhaust is touching anywhere ? there will be rub marks if it has. My guess is its going to be wheel bearing or CV joint.
Another good test is to jack the rear drive wheel stick it in second gear and turn the jacked rear wheel back and forward to see if there is any play ,knocking or graunching noises. Give it some stick to replicate being under load.

Try get someone else to drive the car and sit in back and listen around. Feel the flooring etc see if you can pinpoint the location of the noise.

Do you get any noise when you de-accelerate ? is there any clunk when you accelerate and deaccelerate sharply in third or forth ?
 
No theres no clunk at all just the knock knock knock which increases in frequency as you speed up and I believe its coming from the rear drivers side. I will have to get it on the ramps again this weekend and have another good look round!!
 
ORIGINAL: nick3814

Further to my original description, it was quiet this morning on the way to work, stopped at some lights, when I pulled away it started again, then the next time I pulled away it had stopped [:mad:]

Came home this afternoon, down a slight hill with no load on in second gear just coasting and it started again, knock knock knock, definately metal hitting metal, quite loud, I depressed the clutch and it stopped instantly, let the clutch out and it started again so I'm assuming its drive train related yet theres no problem in the way it handles or drives, just this damn noise [:(]

Any further ideas chaps [8|]
Click to expand...

It is possible it could be the clutch breaking up. Mine took nearly a year to fail and gave very similar symptoms. The most noticable was the clonk felt and heard when accelerating and deaccelerating because the rubber do-nut on the clutch had become detached and the drive was surviving on the `get you home' metal metal retaining clips .(not quite sure on how it works)
 
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