53 plate 1.9 TDI Octavia Estate L&K 130bhp 165k miles

Car has recently started making a loud knocking noise at idle accompanied by jerky power steering. This disappears above walking speed and car drives perfectly from then on, until speed reduces towards a stop when the noise kicks in again. I'm assuming it's power steering- related, but have no idea how serious this is or how easily repaired. I've checked the power steering oil reservoir which is at the correct level. There are no warning lights. No kerb clip prior to this starting.

Any ideas?

Is it making the noise when you turn the wheel lock to lock when stationary?

pop the bonnet and watch your strut top mounts while you turn lock to lock. if they move in a jerking manner, your bearings are gone in the top mounts. Pretty easy repair so hope for that.

Michael

Hi Michael,

Thank you for your prompt and helpful response. I've just been out and done what you suggest. The strut top mounts (I hope I've identified the right part) are proud of the chassis as photographed and move smoothly when the steering is turned. The part by the alternator (arrowed) vibrates wildly at idle, but stops as revs are increased. No idea what it is or why it's moving. Hope this helps.

Thats your auxilarry belt belt tensioner, could be knackered !!

Which I guess could make the noise, your pas pump runs off this iirc

Ok, thanks David. Looks like it's time to get the belts off and have a look!

Ah yeah, whenever the load comes on from the power steering pump it tensions the belt and I assume makes the noise go away. so to do the increased revs.

As stated above, the bit moving is tensioner. shouldn't be expensive or hard to change. if it is moving wildly it is fecked and needs fixed asap. if you leave it for long it will start to wear the bearings on your alternator etc. so do it asap.

Does the noise change when you turn on headlights or fans, aircon etc?

I would think it is likely that the alternator pulley is kapput which has in turn killed the aux belt tensioner.

Edited 26 November, 201213 yr by trundlenut

Car's going into the garage next week so I'll pass on your suggestions and report back.

Thanks for all the ideas!

Belt replaced, tensioner replaced, noise gone! Thanks for all your help - my local garage wanted to check the steering rack (big job), but tried the tensioner idea first.

So, you saved me a packet of money - thanks!!