Water cooling help

[NecroFlex]

https://image.prntscr.com/image/88baa75516cf4c7fa12a378fd122dc64.png The CPU block

Ok so i have a really old system:

http://koolance.com/pc2-650bk-liquid-cooling-system-black

Surprisingly works well still, had an old P4 in it, but decided it was time to disassemble it. I want to know if that CPU block is still ok, it doesn't have leaks but idk what the colour there means, is it still safe to use?

Technically the block is for the P4, but i could probably make an adaptor for newer boards.

For anyone curious, the whole system looked like this: https://image.prntscr.com/image/bd68ca767aac41e4be965159aab66e26.png

Please excuse the cable mess, couldn't get it to look better.

 

Also, any tips for the pump/tank combo and the radiator? I cleaned the whole loop with distilled water but is there any other thing i could use to clean the loop and get rid of any residue or any trash that's still stuck in it, if there is any?