BKD engine noise, loud tapping

[dekhelia]

Hi all, I have a 2008 Golf TDI GT Sport. It's done 177k but after a recent turbo replacement still pulls very strongly. However it does have a loud tapping type sound coming from the area of no.4 cylinder at the upper end of the engine. I realise with a diesel that it's difficult to pinpoint the source of any untoward sound, but I used the long screwdriver-to-ear method and the area above cyl4 seems the most likely culprit. After a long run with the engine fully up to temp the noise decreases significantly, but it's definitely still there.

I'm new to this 16V motor, and was wondering if there is anything obvious I should check first? I've had the cam cover off to replace a duff glow plug, but nothing about the way things looked under there set off an immediate alarm.

Any pointers gratefully received!

[Crasher]

Possibly a worn cam on an injector rocker but as the noise fades when hot it makes me think hydraulic tappet so a good flush and top grade 5/30 oil may help.

[dekhelia]

Ok thanks, that's good to know. My gut - which is probably not the best rational method of discerning such things, apart from a good few years of having to learn to listen to it - tells me that it's more than a flush and fresh oil that's required. I mean, it'd be great if this were the case; so on that basis, I'll try your suggestion first. What is the best thing to use, to flush the system? And if this doesn't work, how do I determine which is the worn cam on an injector rocker - and are these straightforward to replace?

[Crasher]

If it is that old a problem it is probably a faulty hydraulic adjuster but they are a right sketch to change.

[dekhelia]

Sorry, I didn't make myself clear there. It's not that the problem is years old - I've only recently acquired the car - but that my gut instinct, for good or otherwise, is something that has developed over a number of years attending to poorly cars.

I'm going to look up the procedure dor checking and adjusting the injector cam clearances; if it's something I feel I could do I'll have a go, but if not I'll see if I can find someone localish who is familiar with these engines.

[Crasher]

You set each arm at max lift on the cam lobe and wind the screw down until it reaches a firm stop, then back it off by 180 degrees.

[dekhelia]

Ok, that seems simple enough. It'd be great if this were the problem, and that an 'old-fashioned' fix may be the answer. Other than the tapping, it's a great little car - huge power to weight whatsisname, lot of fun to boot around....but 60mpg with a light foot. Amazing motor, really. Will report back after the weekend, when I've had a chance to tinker. Thanks, Crasher.