A few weeks back I had a 2011 BMW 335i come in for an overheating issue. Nothing out of the ordinary, coolant level was full, no leaks, but it had a few faults in the engine computer (DME) that regarded water pump speed. These can differ in wording, depending on what scanner used, but typically they say something along the lines of, water pump failure. In this video I go over a few tips on replacing the water pump, and thermostat.  Is it necessary to replace the thermostat also? Not exactly.. but considering the cost of it, if your willing to tackle the water pump on your own, you will save more than enough to make up for the cost of it. The benefit is piece of mind in that you wont have to crawl under there again for some time.

The main PITA to doing the water pump is the upper hose clamp that goes on the T-stat, and torquing down the new water pump bolts. The hose clamps are all 6mm from the factory, as well as phillip screws, but I suggest using the 6mm. The smaller your tools, the better. Especially when dealing with the upper clamp that sits by the frame. When torquing down the new water pump, just take your time and find the exact angle and placement of your wrench for the upper bolt. The bottom 2 are both really straight forward. Besides removing the actual thermostat and water pump, the only thing that needs to happen for disassembly is: taking loose the four 13mm nuts and letting the sway bar hang, and the 10mm nuts that hold the bushing for the powering steering loop. Also of course remove the under tray.

This video shows a lot of the work in more detail, and forgive me it was the first video I ever shot as far as a DIY video goes.