Cold start knock 2.0tfsi

[AvantAlexB7]

A few month back i was greeted with a knock at idle when i started the car one morning. It only happens when to engine is cold and soon goes away, if it does it at all that is. It only does it at idle and stops if you rev the engine, but starts again when returning to idle. It seems to be an intermittent noise. Sometimes it does it, sometimes it doesn't. I've not noticed any change in performance and no eml either, it just doesn't sound great and can't be normal. Also poked my head under to bonnet to but can't seem to locate it so im at a bit of a loss really.

Any thoughts are welcome!

Cheers Alex

 

[Charlie Farley]

Hi Alex,
not seen you posting recently.
Before you panic and assume it's the cam chain/ tensioner , check the vacuum pump as it can be very Rattley indeed and given its bolted on the back of the timing chain cover it can very easy to assume worse case situation cam chain.

 

[AvantAlexB7]

Hi Alex,
not seen you posting recently.
Before you panic and assume it's the cam chain/ tensioner , check the vacuum pump as it can be very Rattley indeed and given its bolted on the back of the timing chain cover it can very easy to assume worse case situation cam chain.

Hi Rob, thanks for your reply. Nope been a busy bee behind the scenes and not had much time for either the forum or the car to be honest but thought I'd best look into this issue!

Just found an old post actually suggest the vacc pump, then the timing chain. Hopefully its nothing major or expensive, its just damn annoying!

 

[Charlie Farley]

As you can't easily inspect the cam chain and tensioner for wear you need to be a bit careful before launching into a repair unnecessarily.
check the vacuum pump first.
The cam chain/tensioner wear does manifest itself with a cold start-up rattle that lasts for seconds until oil pressure is reached, and on an 80K mile engine, it will have worn to a degree but not a severe point.

 

[AvantAlexB7]

There's always been a little bit of chain rattle on start up, but apparently thats normal on our engines anyway. Im currently on 129k so we're deep into parts wearing out territory! Also if it was the chain/tensioner, i would have thought it would be knocking all the time. I only occasionally have the issue when cold starting. Any suggestions on how to check the vacc pump?

 

[Charlie Farley]

Strange really as there have been a few guys posting on the cam chain rattle recently.
There is an easy way to check the vacuum pump but I can't recall what it was, it's been a fair while since the question arose.
I'll have a think but it's a more lightweight alloy rattle than the cam chain tone if that makes sense.

 

[Charlie Farley]

The vacuum pumps also tend to leak oil as well after a few years.
From memory, the vacuum pipe comes off the side of the vacuum pump at the very back of the engine.
Earlier revision pumps where the plastic part on the vac pump body can get a bit loose and cause a rattle.
worth a check first, otherwise your tensioner pad may be worn down to the point that the slack in the chain is causing the rattle when oil pressure is low such as start-up etc, in which case you need a new kit.

 

[Charlie Farley]

just found this link for you Alex, may help a bit with sourcing the rattle.

audi a4 b7 2.0tfsi vacuum pump rattle - Search Videos

www.bing.com

 

[Charlie Farley]

As you know these engines do tend to sound like a bag of loose spanners on idle at the best of times, fuel pump/injectors /vac pump etc without mentioning the cam chain so a case of narrowing down what has been replaced and what hasn't and then look at what left.