Coolant pipe perrished - 1.9 TDI

[mrcheeezy]

1.9 TDI 2003 A6.

The top coolant pipe that goes round the back of the engine under the tandem fuel pump was leaking. On removal it has perished where it sits next to the tandem pump as if contaminated by oil etc but it is ok elsewhere. Are the tandem fuel pumps prone to leaks?

Is this the likely cause?

Thanks Paul