bosch 4.0. Started to get hot on the way home from work, stopped and put water in to cool down. took some jugs with me to limp home stopping frequently to put In more water. overheating light came on once for about a minute during all this time but water seemed to be boiling out. Replaced waterpump thermostat elbow pipe and radiator. Now overheating quickly with temp gauge showing running temp, went to a shop to help me bleed the system with no luck on stopping the overheating. Temp gauge reads normal with water boiling out. head gasket? warped head? cracked block?

 

I guess I will chime in first. First the temp gauge stinks in this vehicle, it really has three positions, cold, middle and overheated. I would bet you need a new head gasket, but a coolant pressure test or engine compression test should be done to confirm. Anytime I have done a head gasket change (just did one on my disco) I assume the heads are warped and get them decked. It's not much more to get a place to deck the heads and it would be a shame to do the head gasket only to find out the heads are warped after you get it all together.