XF SV8 4.2 start up rattle

[1969fastback]

I have an XF SV8 with the later version of the 4.2 supercharged aj-v8, its a 2008 model with 102k miles on, good service history.

When I start the car there is a rattle for around 3-4 seconds, I have done a lot of searching over the past few days and found little info, however what I have found points to the timing chain pre-tensioner

Has anyone got any experiance of this issue with these engines? (also used in 2006-09 XKR and maybe XJR) I understood it was a big problem of earlier ajv8 engines but thought the later 4.2 was concidered "bullet proof" - quoted several forums etc

I have it booked in with a specialist (jagtech) to get looked at on the 30th, just my main concern is wether my car is safe to use until that point or not?

[P700DEE]

Whilst the later 4.2 engines have metal tensioners, better chains and guides there is no such thing as bullet proof 100K miles is certainly when you should consider inspection, the slippers on the tensioners must be plastic and can fail. You can also get faulty tensioners etc.

That said the most common noise on start up is one of the belt tensioners , either belt or bearings. Later cars have VVT and these are known for causing a rattle on start up when they get worn.

You are probably quite safe to drive until you can get the car inspected, just watch for any missfire that could indicate chain slip.
Sorry no diffinitive answer.