Engine cold problem

Hello , i had an Octavia 2l tdi 2011 for about 3 years , it’s a taxi car. 30k miles ago i changed the water pump with timing belt and since then water level didn’t reach 90 degrees. I first changed the thermostat (twice) both genuine parts, no change. I replaced the temperature senzor still the same .

Would like to say that now when i put ignition on after 1 min ventilator will start and idle will be at 1080rpm. 

I am thinking to change again the water pump and timing belt .. Please anybody have any idea about this problem .