Over heating problem

[Ppsa4]

Hello guys, am new here so please be gentle. Also sorry for the jump on and question straight away.

can anyone chuck any light on this, the car over heated a few days ago so called the AA who diagnosed a faulty thermostat. On their word I purchased and replaced the part. The guys who replaced it said he bled the system and topped it up etc.

Took the car for a drive locally and all was fine, so I ventured further out and noticed when accelerating to 70mph the temp would go up but then come back down when I slowed.

When I open the header tank cap the water bubbles up and over flows, have also noticed a clicking noise coming from the area of the thermostat and can also see the return pipe twitching when it clicks.

please somebody shed some light and helppppppp.

 

many thanks guys

 

[James]

Possibly the water pump?