My E53 Diesel has had the Crank Pulley replaced twice once with an OE part and now a BMW replacement part.

This seems to have resolve 80% of the strange engine squeak all I am left with is a squeak from the air con tensioner.

If I lube the tensioner the noise disappears however I replaced it this weekend and still the issue resides.

It is driving me crazy.

All the belts and tensioners have been replaced including the Air Con pump and still I have a squeak.,

Any ideas welcome.

Stuart