Hi first post on this forum and some advice needed please. I have a TD4 with 67K miles, last week whilst changing a cracked expansion tank I noticed a small amount of oil/diesel, on the right hand side of the cylinder head. I took the engine cover off and cleaned it up around the inlet manifold and injectors. Following a further 150 miles I have had another look and it has returned, I can't however see where it is coming from, there does not appear to be any residue on the pipes going to the injectors.

The car itself starts and runs fine. I have attached some photos, the oil is cicled in blue.

Any suggestions greatly appreciated.