Defender 300 water pump

Hi All
I have a little problem with overheating, my gauge goes up to red and I have found the thermostat housing was hot but top hose cold. So I change thermostat but no different.
So here `s the question, could it be the water pump ?, I`ve always thought that if the water pump failed it would be noisey , or water lost but there`s been neither .
I cant think what else it would be.
thanks all

Same old question in reply to your question - Have you checked that your engine is actually overheating or if it is just a gauge fault?

With regards to the top hose, that could be completely normal (unless it never gets hot that is). The top hose won't be hot until the engine has reached normal operating temperature and the thermostat has opened to allow hot water to pass through the radiator to be cooled.
Have you checked the top hose after you have been for a drive and you know the engine is up to normal operating temperature, at this time of year it is unlikely that the thermostat will ever open with the engine just idling (even with the viscous fan removed)?

I have driven the landy a few times this week, and initially thought that it was the sender.
When you touch the thermostat housing its very hot, the rad top is cold the expansion tank can be opened and the water is cold, as is the top hose.
I think the water is not circulating, hence my `same old question`.
I`m just not sure

the top hose could be "cold" if no water is passing through it, so you could be right.

might be worth getting it off to have a look!

If you take the pump inlet pipe off (and the belt) you can insert a long thin screwdriver (or similar) in to the pump and feel the internal impeller. Try turning the pulley and you should feel it stop as the screwdriver holds the impeller. That will prove the impeller is securely attached to the shaft.

Also if your heater works well then that is a good sign that the pump is working.