Coolant leak on AWX diesel. Now fixed :)

[desertstorm]

Seem to have developed a small coolant leak on the back of the head below where the coolant temperature sensor housing is.
It's really hard to see back there hopefully it's not the head gasket weeping I am hoping it's the O ring seal number 4 in the diagram thats leaking.



Has anybody had anything similar on their car or could Chris or Dave give me any pointers as to whether this is a common problem. Looks like a bit of a s__t to get out looks like I will have to take the tandem pump off to be able to see what I am doing.

Thanks Karl.