Thanks for the info - I have done some more reading up myself.

It would seem that the service manager has been feeding me b*lls**t.

Like you say Bullfrog this EGR valve should be closed under full acceleration, deceleration and at idle and open under lean fuel conditions such as small throttle openings and cruising.

It certainly wont be opening and closing rapidly in line with engine rpm and clicking.

Its definitely too loud to be the injectors and more metallic in sound so not that.

I would swear its a lifter ticking but they are quiet at idle which is confusing.

The problem now is that I have to go back to the dealer and basically tell the service manager he has told me a load of b*ll and then ask the same guy to find what's wrong with it when I no longer have any faith in him. I always prefer to work with people rather than against them for best results but I cant see him taking it well.

I will also get the long winded 'its normal engine noise' comments etc etc.

I know this isn't normal engine noise and I am not being over sensitive - when I accelerate under load from 1500 rpm upward the engine is making a metallic ticking sound, which gets louder with an increase in load.

With the windows down, my mechanical sympathy makes me lift off the throttle as it tick, tick, ticks. I can even hear a faint metallic ticking on a constant throttle now at around 2000 rpm with the windows down.

The car was quiet up to approx 2000 miles but the dealer just says it has loosened up and you should expect some noise ??!!

I would like to take it to a Merc dealer to see what they think but its not easy approaching them and getting help when your not paying for there time, especially as it would involve taking the Tech out in the car as the engine is pretty quiet at idle.

Looks like I am going to have to go back to the dealer again this week but don't relish having to inform the service manager that he doesn't know what he talking about regarding the EGR valve.

I will ask to drive another one while there but they don't usually have any manuals.

I could really do without this to be honest. Its a good car but one of the reasons i bought it was the smoothness of the V6 engine and mine sounds like an old ford escort with unadjusted tappets at the moment and its becoming a real headache to get the fault recognized, let alone resolved .

I am even considering selling it but I cant think of anything else for the same money i could buy instead.