Bongo Fury

I havnt seen this yet so bear with me - apparently our bongo is spewing water from a metal pipe that has rusted it's about half inch thick and connects too (i think) the main top hose the pipe runs alongside the chassis and under the air cleaner . does anyone know what this pipe is and an if it can be replaced or where i can get a diagram to identify it.

The place for diagrams is here at Lush Projects.
I'm sure that those more familiar with the coolant system will soon suggest which pipe it might be.

rear heater return pipe ??? See if ycan cut a bit out and "fill in" with a bit of hose and 2 clamps

thanks guys - amazing how quick the replys were - I've printed a piccy it looks a bit complex -the hose idea sounds good - we replaced the hose before and i seem to remember some-one saying they,d shortened theirs to stop it touching something hot so we may have a spare bit to hand - sorry i sound so dumb havnt seen the bongo yet just a panicky phone call and thanks for ideas.