Timing Chain

[frasermk5]

Is there any way I can check if the chain has stretched through looking at the live data? Got a rattle right when the car fires up on a cold start and a slight chain ticking noise at idle, goes away when revving.

[skkane]

With the engine up to temp plug in VCDS and go to measuring blocks, group 093. If it's over +/-5KW then it's stretched and needs replacement,  according to Decimal Tenths. Also, on group 091, spec should meet actual or be within 0.5 kw if it's timed properly

&t=914s

[akbarirfan]

Is there any way I can check if the chain has stretched through looking at the live data? Got a rattle right when the car fires up on a cold start and a slight chain ticking noise at idle, goes away when revving.

The chain tensions under oil pressure, so a start up rattle is normal, a prolonged rattle is not normal!

Measuring blocks 091 and 093 when the engine is up to operating temperature will give you good idea.

[colesey]

Have you checked the oil level? I had this noise at idle last winter before the engine had warmed up. Found that the oil level was low and the noise went away after topping up.

[pudding]

Rattling could also be the VVT as it advances a lot on start up for the EGR function.

[ROH ECHT]

In addition, the whole cam timing system operates by the oil fed through it.
If you see data pointing to chain stretch, it may not only have a slightly stretched chain.
It may have restricting oil leading to and through the system. To include the chain tensioner and its inlet screen, the N205 and its inlet screen, and cam adjuster and its three inlet rings (the three rings between the N205 and cam adjuster may be allowing oil to escape the system).
What I'm saying is do not only address the chain. A new chain tensioner comes with a new/clean inlet screen. The N205 inlet screen must be removed from the cam adjuster cover and cleaned. Also, prepare to replace the three rings. You might even consider dropping the sump, to clean the screen of the oil pickup tube.