Superb Estate, 2010, CFGB, 78k. Standard, no mods, QG1 servicing regime.

On occasions I get a tapping noise from the engine when started from cold, it can last for 15 minutes if left to idle (I never do that apart from checking this problem), or it goes away after a 5 minute drive and the engine warms up.

I've done an oil and filter change and it made no difference. I know it isn't that quiet ticking that is common on all CR units.

It sounds the same as the worn lifters you get on an old Ford CVH engine.

Is there anything else it could be? a noisy injector perhaps? No faults found on VCDS

I know there are various additives you can sling in the engine such as the Wynn's lifter treatment but I've not used them before.

If the lifter oil feed is blocked, is it a reasonable DIY job to remove and clean? or replace if FUBAR?

Thoughts and comments please, there aren't many documented examples of this online and it appears to be getting more frequent :think:

This could possibly be what I have heard called a lazy tappet. I have had a number of newer cars that exhibited this noise and to my knowlege none were any the worse for it. Of course a much older car can suffer loss of oil pressure because of worn bearings and this can make it difficult to get sufficient pressure into the valve lifters. If its a lazy tappet the noise will go away when the car is warm. If its is a worn engine, it will not.

When the engine oil is cold it doesn't flow as well as when it is warm. When the engine is idling with cold engine oil, having just started from cold, idling oil pressure can fail to fully pressurise all the valve lifters. This leaves you with one or more noisy valve lifters until the engine oil is properly warmed through, or until you start driving, when oil pressure will increase and stop the problem.

If it's a new noise, and the car is still under warranty, I would get to the dealers. It sounds like a faulty tappet (or rather the hydraulic lifter), which should be replaced.

Unfortunately the car is out of warranty, its over 2 years old and over 60,000 miles.

The 'lazy tappet' description sounds like the most plausible thing. Once the engine has some heat in it and (as you say) the oil has lost some viscosity the noise does indeed go away. When cold, a fast idle of 1200 rpm is enough to quieten it down a lot.

I might go with a few engine flushes and more frequent oil changes to see if it will sort itself out. If there is a slight blockage a few flushes might help it.