I have been getting a tappy noise sounds like cam chain when the engines cold, as soon as it starts to warm up its stops, so today i swapped the cam chain tensioiner with another one i had in another engine, and it made no difference at all, i did notice that there was groves on the head where the chain has been hitting when cold, the engine has full vw service history and its done 94k ive had the car for 2 years, i brought it with 80k on it, its made the noise from when i brought it, i also dropped the sump and replaced the oil pick up pipe too, it wasnt blocked and theres hardly any sludge either, has anyone had this problem too? like i said soon as the engine starts to warm up it stops and sounds sweet as a nut, but if i turn the engine off even when hot for a about ten seconds the noise reappears untill i drive it, any info will be much appreciated