Whatsupppp

I have a Mk1 Velocity 1.4i
A few weeks back I replaced my cam belt and tensioner.
I drive the car today and when ever I let go of the throttle there is a knocking sound.
I expected when I got home. It seems it's comming from my belt area at the bottom
Could it be a faulty water pump?

Could also be that the belt tensioner was not tightened and has come loose slightly letting the belt clatter against the cover. Noises are always hard without hearing it.

Thank you.
Ive noticed that the knocking sound is only there whe the the car is cold and goes away after the car has heated ect.