Colt loosing water

I have a colt Pioneer 2800tdi

You fill the radiator with water, you can then drive for about 5km
before the vehicle overheats. What could be the problem. There is no
visible place where the water is lost.

Any ideas

kobusc DeleteThis @value.co.za wrote:
> I have a colt Pioneer 2800tdi
>
> You fill the radiator with water, you can then drive for about 5km
> before the vehicle overheats. What could be the problem. There is no
> visible place where the water is lost.
>
> Any ideas
>
First most common suspect is the head gasket.
Open the radiator cap and see if its grayish, gummy looking inside there.

GK