Coolant "over engine" pipes

[Riccardo]

Hello, I was wondering whether there are any signs or warnings as to when these need doing?

When I drive with my window down I can smell a faint whiff of coolant once the engine is warm. Its very elusive but consistent. The level is stable in the header tank, car doesn't over heat at all, rads show no leaks, garage floor has no drips... I already did the "cross over" pipes at the front a few years ago.

I was wondering whether the smell might be coming from these pipes?

 

[D5RSR]

The joints corrode where they join onto the plastic pipes. Hard to see as they are covered by the undertray.
Could be weeping onto the tray?

 

[911UK]

As @D5RSR said, look out for leak signs if you remove the under trays