Unidentified knocking

CrispyEdd

CrispyEdd

Member
United-Kingdom
Ahhhh just when you thought you could have a few months peace your A2 delivers more work, the needy little blighter!

I have deep thud/knock, rythmical - like if you stuck a rubber mallet on your wheel and it hits the lower arm?... Its definately something going round and round!
It happens when i come off power and coast, cant decided if its happening with clutch in yet. Its stops when i put power down or brake. It doesnt happen over bumps and I cant see anything loose like undertray so far.
punching the accerlator on and off to rock the engine while going slow in first or second gerneates a little knock.

There isnt a vibration at all and car drvies brakes perfectly, mpgs okay. No recent work other than outer track rod ends 4 weeks ago and cam cover refit last week.
It sounds serious to me but no effect on drive.

Could it be driveshaft wear or gearbox output bearings? Anyone have an easy test for this?

Im going to keep driving until it get worse to help diagnose it as I cant take a photo of anything or video the noise so guess have to wait for failure.

Thanks fellow patient A2 owners.
 
After making sure the wheel bolts are all correctly fitted and torqued. Check the engine mounts for wear or loose bolts especially the pendulum mount for the rubber bush failing or loose bolts.
 
Coming home tonight it's happening when engine coasting or feathery throttle. Steering doesn't change it. Will check wheel bolts after kids asleep, occurred to it may be them as I got home.
 
Had a knock on my Tdi project car that started around Christmas time. I was convinced (after a lot of reading here and based on precise timing of symptoms with road conditions) that it occurred when the driver side strut was under compression cornering, then hitting a bump, and that it was the strut top nut momentarily coming away from and then returning to the seat it sits in just under the edge of the windscreen : so the cure would be to tighten up the top nut (having shifted the Webasto and brake fluid reservoir). My local mechanic sorted it out just before Easter - the rear control arm bushing on that side was toast and the other one wasn't great either (there is paperwork to say that the other side was changed 5 years ago, the car is now >290k but only about 5k done in that time due to various mechanical ailments keeping it out of much use since mid 2018). . New cast arm and bushing replacement later the knock had vanished.

However - your knock is rhythmical, suggesting something rotating. On my other Tdi A2 this turned out to be a CV joint going bad. Unlike previous experiences of CV joints in other vehicles (2CV, Metro) that were quite "clickety" sounding, particularly coming out of junctions on lock, surprisingly the noise (that went on sporadically over several months in 2019) only exhibited itself when using the torque in a straight line and it was a series of deep speed-related clunky noises from the lower left side of the car - I could hear it but no-one else in the car really took any notice of it. It deteriorated gradually and I ended up fixing it by getting a new full JR driveshaft for that side that was fitted at the same time as the PTW gearbox. So perhaps it was the inboard CV joint rather than the one right abutting into the control arm steering components (if that makes sense?)
 
Robin_Cox said:
Had a knock on my Tdi project car that started around Christmas time. I was convinced (after a lot of reading here and based on precise timing of symptoms with road conditions) that it occurred when the driver side strut was under compression cornering, then hitting a bump, and that it was the strut top nut momentarily coming away from and then returning to the seat it sits in just under the edge of the windscreen : so the cure would be to tighten up the top nut (having shifted the Webasto and brake fluid reservoir). My local mechanic sorted it out just before Easter - the rear control arm bushing on that side was toast and the other one wasn't great either (there is paperwork to say that the other side was changed 5 years ago, the car is now >290k but only about 5k done in that time due to various mechanical ailments keeping it out of much use since mid 2018). . New cast arm and bushing replacement later the knock had vanished.

However - your knock is rhythmical, suggesting something rotating. On my other Tdi A2 this turned out to be a CV joint going bad. Unlike previous experiences of CV joints in other vehicles (2CV, Metro) that were quite "clickety" sounding, particularly coming out of junctions on lock, surprisingly the noise (that went on sporadically over several months in 2019) only exhibited itself when using the torque in a straight line and it was a series of deep speed-related clunky noises from the lower left side of the car - I could hear it but no-one else in the car really took any notice of it. It deteriorated gradually and I ended up fixing it by getting a new full JR driveshaft for that side that was fitted at the same time as the PTW gearbox. So perhaps it was the inboard CV joint rather than the one right abutting into the control arm steering components (if that makes sense?)
Click to expand...
Thank you, that's a well written piece, I think you could be onto it with that cv joint description, I'll take it to garage and get it checked for play.
 
So its got a bit worse, shouldnt be long until i can tell what it is! Definately when driving easy and in gear, engine braking and accelating its not discernable. Given the issues a lot of people have had with sourcing correct length drive shafts etc etc has anyone got a definite guide to drive shaft cv joint sizes for the A2?
 
@depronman recommended JR driveshafts (that are available direct from their webshop on Ebay) - I've used these for all of mine (1.4tdi in particular) and they have been fine.

If you search "JR driveshaft Audi A2" it brings up a decent list of parts for all common variants (don't know about 1.2Tdi though) - for instance :

jr driveshaft audi a2: Search Result | eBay

Find great deals on eBay for jr driveshaft audi a2. Shop with confidence.
www.ebay.co.uk

although obviously you could be more specific for a direct link to a needed part.
 
Hmmmmm so now I've got time ill update you. The drivers side wheel was loose. All bolts only finger tight. Last time wheel was off was at a garage to do track rode ends two weeks ago. 😳 believe it's solved now. Thank goodness no more money involved and it didn't fly off while on motorway.
 
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