My old fellow (A MBP 2006) started to be noisy. The left fan was making a sound like a blender at top speed.
The guide was incredibly helpful, the problems start when I tried to open the upper case, I broke some parts of it (Where you put the screws). Then I realized that some tapes where put on places not showed on the pics from Ifixit. and the cable from the sensor light was almost welded to the fan.
But the guide was the key, It showed me how to properly arrange the cables and tapes in the case and the replacement was fast.
Have a printed guide with you and be prepared to get some different arranged cables and tapes.