Severe coolant loss..

I have an Audi A4 1997 1.9 Tdi (110). The car is suffering from sever coolant loss. I have noticed then when the car is cold and stationary it doesnt really leak much, if atall.

I can fill the coolant expansion tank right up and little, or none will be lost. But then If I take it for a drive, say to the local supermarket, I will come back from getting my bits and there will be a HUGE puddle of coolant under the audi.

I don't have a clue about audi's. But I put it up on some ramps and it is so hard to tell where it is coming from. Because it only leaks when you take it for a drive. I suspect the water pump but I could be completely wrong?

Is this an expensive repair and is there anything I can do to fix it temporarily as I have to use the car over the weekend? I have tried radweld.

I've just been having a closer look at the car. I started it up and noticed it leaked slightly. Had a look under the car to see where it was coming from, but it was extremely difficult to tell..

..eventually, I traced the leak to a small whole in one of the main water hoses, at the top of the engine just to the left and below the fluid reservoir.

Do you think this is the only problem? I mean can such a small hole in a hose account for such huge water loss? Or is there likely to be another problem? I know I will only be able to find out by replacing this perished hose.. but it seems wierd that the higher it revs the more water is lost. Can such a huge amount of coolant loss be solely attricutable to such a small leak in one perished pipe?

Cheers guys... oh, I was wondering if there is anything I can use (any kind of special tape or something) that will temporaily fix the hose until I buy another one and get round to fitting it?

It could account for it why dont you run the car and look in the engine bay for leaks when its warm. Remeber the coolent system does pressurise a bit with the heat causing expansion + the water is beeing pumped round.

Thanks for that mate.. I think I will do that now. I have put some duct tape around it to see if that will temporarily fix it until I can but a new pipe. It doesnt leak atall now when standing.. but I bet the duct tape will give way as the pressure increases! only one way to find out...

P.s.. The piping I am talking about is the main pipe that connects the oil cooler and the engine. I think All I need to do is take the air intake piping off to get access to it?

Cheers for the help mate. Will report back later!