Can anybody help identify the noise my boiler is making ?

[CraigG87]

Hi , I'm wondering whether anybody can help me at all ? My boiler has started making noises which I am unable to identify. If anybody is able to guide me to the route of the issue itll be massively appreciated. I'm looking for an idea of how much it will cost to get it repaired.

The water has started to run cold towards the end of a shower.

Thanks in advance !

 

[Gasmk1]

You shouldn’t have the case off

 

[ShaunCorbs]

As above it’s an overheating noise