Fuel Leak And Loss Of Water(Coolant)

Hi guys

Hope you can help me, I have a (58) mondeo, never owned one before.

I thought I had an oil leak or leak from the gear box but the oil was/is clear that's why I thought it was from the gear box.. But I was checking the coolant level and it was low, i noticed a smell of fuel, couldn't see where it was coming from.

I went to my mates and he had a look, he thought it was oil from a pipe at the top of the engine and it was dripping down. replaced the clip as it was very loose. He had a look at the glow plugs and smelt the oil leak, turns out it's diesel.

He said it was either the seels around the glow plugs or the fuel return pipping.

Does anyone know how much these would cost, mate won't do it was he is away for a few months with work.

Also he said the water/coolant lose is down to the diesel leaking onto the engine and the water/coolant is evaporating... Do you think that is correct?

cheers

Brian