pajero sport - water flow issue

[PajeroNewbie]

Good Afternoon

2014 pajero sport 2.5 DID

The top pipe to radiator gets hot, bottom going to Thermostat stays cold. Thermostat checked and is OK (by putting in a kettle and it opens). Silvertons have had the head tested and is Ok.
Have removed the radiator and pushed water through with a hose pipe, water flows out easily
Water pump issue?
water pushes into overflow bottle.
heat gauge does not move and never had to stop because of overheating

anyone had the same problem or similar?