td5 Overheating ?

Got a baffling problem with a TD5
Has 100k on it but lower mileage replacement Engine
Been Tuned by Twisted

Temperature Gague Normally just on half or a fraction Higher
Sometimes when going up hill Engine Falters Temperature Gague goes up and Red Warning Light above it comes on and usually Engine Cuts out
Leave it a few Seconds Temperature drops to normal and light goes out and Engine runs fine
Seems to use a little water
Cant find anyone round lancashir ewho knows about these things does it need a new Head Gasket or is it something Else
Any ideas

what do the coolant hoses feel like? Are they going rock solid? Is there any signs of coolant loss from around the cap on the expansion tank? My TD5 eats expansion caps and coolant temp sensors. If you loosen the bleed screw on the top hose when the engine is cold, and then run it up to temp are you getting bubbles coming out? Are there any signs of oil in the expansion tank?

The coolant systen works on suction by the water pump rather than pushing the coolant around. The water pumps are prown to failure as are the twin valve thermostats. A traditional thermostat opens when hot. On a TD5 one valve opens when hot and another bypass valve is sucked open when the engine revs exceed 1500rpm. If the valve jams, waterpump goes weak/fails or the expansion cap pressure valve fails this will result in lost coolant pressure so the coolant will not circulate properly.

A thermostat is around £15, water pump £25, expansion cap £5-£10 depending on the model and a coolant temp sensor is £15.