The fans were making a lot of noise and the computer was overheating.
The repair went very well, I replaced the two fans and I added another harddrive to the device. The repair kit which also came with the order gave me all the tools I needed. No damage was done and now my machine is running with two new very quiet fans and a very fast ssd which my operating system now sits on.
Definitely buy the repair kit from this site with your order, it's very handy and will give you the tools you need to get the job done quickly and safely.
Also ssd is the best thing that ever happened to my mac, my machine now has at least a 5 second startup compared to a 1 minute startup it had with the factory 500 gb hdd