Knock on pulling away/slowing down - 2.0TDI

[RapidAssistant]

I have seen this particular issue before with B8 platform Audis on other forums but can't seem to get a definitive answer...so trying again.

The car is making a distinctive "knock" or "cracking" sound when you move off, and makes it again as you are slowing down into a junction. It seems to be coming from the front RH side.

What is baffling is that it doesn't do it once you are travelling at speed, or when you are going over bumpy roads which , if logic dictated, would rule out a suspension/steering issue.

I've heard on some forums that it could be an engine mounting which are a known weak spot I'm also hearing things about loose subframe bolts, or something as silly as the exhaust pipe knocking against the underside of the car. I am coming up to MOT time soon, so would like to get a handle on it before then. Anyone had a similar problem?

 

[ruairi83]

Have you had clutch replace or any work under car?

Have you checked subframe bolts? Had that on wife’s A3 when turning right only. Took to Machanic who said drivers front shock, so we replaced front pair of shocks and still knocked there. Checked online and common on the Audi’s.
Jacked it up and sure enough 3 bolts loose. Quick fix but cost £160 for two shocks and fitting when they weren’t needed.

 

[RapidAssistant]

Have you had clutch replace or any work under car?

Nothing like that no. I have owned it since it was 19k miles and two years old and it hasn't given me any trouble until now. The car has done 57k miles and is just coming up for 6 yrs old. I did a lot of starting and stopping yesterday to try and characterise the issue.

- the knock/creak is more pronounced when you do a hill start, or if you feed the clutch in sharply
- it happens under hard acceleration in 1st/2nd gear
- it doesn't seem to do it as much when the car is warmed up for some strange reason. Equally if you drive like the proverbial granny; i.e. really gently moving off, very gradual acceleration and smooth gear changes - no noise.

All of which seems to point to the engine mountings again......I am going to get it up on a m8's two-post ramp when he has time and have a good poke about underneath to see if there is anything obvious.

 

[RapidAssistant]

Update......I'm still stumped on the problem.

Checked the engine mounts....no obvious issue.

She's been in for an MOT. Passed first time!

Just been in to Audi for a cambelt replacement and they didn't notice anything either during their health check. The undertray would have been dropped as well to do that job so if there had been anything obvious - then lets face it given their hunger to generate extra work they of all people would have been quick to spot something awry.

Any suggestions!?

 

[ThomyJerry]

Had similar knocking as you described, after year and half it stops. Then after some time wheel bearing from same side was squeaking. After wheel bearing is changed everything seams fine.

 

[Meemo]

curious, i had the same knock/bang pulling off and stopping you described, and it was the gear box mounts (not engine) not being torqued in after a clutch change. 3 bolts right in the middle i a triangle arrangement so easy to spot and check, i know you havent had any work but mine worked lose a second time and had to be retightened and then it was no longer and issue, so perhaps this has worked lose?
Other wise super long shot is check the drive shaft/cv joints for any play and as suggested the wheels for play if it is a bearing, if you lift it up on a jack and spin each front wheel independantly by hand, if it doesnt spin freely (ie jolts to a stop ), or sounds like whurring, or can be wobbled/has play thats a wheel bearing.
Fingers crossed, such low miles for a knock to creep in!

 

[spartacus 68]

Long shot, but brake discs and pads haven't been replaced recently have they? Haven't experienced it on a B8, but on B5, then some aftermarket pads didn't sit quite right even with anti rattle pins and you'd get a definite clunk, especially noticeable if you reverse then brake. I'd also check the inner drive shaft splined bolts are correctly torqued.