Found it. Exhaust manifold side between front 2 cylinders.

Thanks Kernow oli and all. The haynes manual refers to a coolant plug on the left hand side of the engine block. I can't find this anywhere. Does anyone have any pointers?

er no. The head is going off for pressure test on monday.

OK - Got head off. The gasket is a 3 hole one. If I don't skim can I just replace with the same? I don't know what I was expecting but couldn't see any breaches between coolant and piston ducts. The gasket was in one piece. I assume the breach is much smaller? I know the best thing to do is...

thanks all. I'll change the head gasket and go from there.

thanks robint. Definately no chance of being the oil cooler? (ever hopeful)

sorry 1996 Disco....

Can anyone help??? I have a 1998 Discovery(1) 300 TDI. The other day I had steam coming out from under the bonnet and found that the header tank had breached at the seal round the edge. I don't know much about this stuff but am prepared to try anything. I have bought another tank and fitted...