Remove cooling hose from thermostat to left intake manifold.
Remove hose from water pump union to thermostat.
Remove hose from thermostat to heater matrix. The overflow hose shown vertically on the "T" shaped union will be replaced by the correct one (cooling system spec one).
This is the thermostat to be replaced. In order to properly access it many accessories had to be taken out.
This is the new thermostat. Note that this is the rod which allows the brass plate to extend allowing coolant pass through. 
In this state, the thermostat is fully closed.
This is the old thermostat. Note that the brass plate sits lower that the one on the new thermostat thus allowing coolant enter the engine radiator.
This is the reason why the engine failed to reach normal running temperature as coolant was able to pass through without being temperature regulated. 
Old thermostat removed complete with the hoses. These will transferred to the new thermostat.
Engine Clean from Turtle Wax cleans away any oil residues on the engine block and regular glass cleaner. Glass cleaner is ideal for rubber hoses or cable harnesses where strong solvents can do damage.
Engine Clean (TM) easily dissolves oil residues which combined with dust make a hard-to-clean compound.
A close-up of the engine block top where Engine Clean (TM) has dissolved crud and the original engine block color has been restored.
This is a good opportunity to replace the fuel hoses as access to them with the intake manifold in place is quite difficult. 
This is the fuel hose to the pulsation damper.
This is the fuel hose from the pulsation damper to the fuel rail. Usually high temperature coming off the engine crack rubber fuel hoses.
New and old fuel hoses.
New fuel hose installed.
New fuel hose installed on the fuel rail
This is the new thermostat and the respective cooling hoses have been installed.
Thermostat positioned on its designated place along with the cooling hoses.
Position the water pump union hose to the thermostat.
Position the heater matrix hose to the "T" union.
Cooling hoses are in place and clamps properly tightened. Note the new overflow hose which will be cut to length once the intake manifold is in place.
Use alcohol and wire wool to clean traces of the old gasket.
Install new gasket on the left lower intake manifold.
Install new gasket on the right lower intake manifold.
Apply Engine Clean (TM) on the intake manifold/plenum to remove any sign of oil residue or contaminants.