BMW apparently has a thing about water pumps. Yesterday I picked up a copy of the winter issue of the BMW Motorcycle Magazine and discovered an article starting on page 62 about a water pump that failed on their new R1200GS water-cooler. The article mentioned that this failure is quite common on the LC engines and apparently is due to a design issue with the pump seal.
There is a hole in the engine case under the left cylinder that allows coolant to flow out of the case and all over your new engine, staining the aluminum with green scum. This is what was happening to the magazine's R12GS LC after riding it only a few thousand miles. Now here is where things get interesting: BMW says they all do that. (Sound familiar?)
The magazine contacted the big guys in Munich and here is what they had to say: “Coolant pumps are usually equipped with axial face seals. This type of seal has a design that may cause a completely uncritical, minimal amount of leakage. Furthermore, over time the seal will adjust, which in our experience minimizes the leakage. The resulting leakage is drained via a discharge hole and a drainage channel in the coolant pump. This is necessary to prolong the lifespan and function of the seal. Below the drain tube a reservoir is located, where the leakage is collected and can evaporate. However, during usage, a negative pressure is created in the channel, which literally sucks up the drops before they reach the reservoir. So even though a leakage might be noticed, it does not pose a problem and can be ridden safely. In our opinion, a change of the water pump in these normal instances is not necessary. If this poses a problem, it should be cleaned and monitored. It is assumed that the light leakage will be reduced by the running-in process. Measures to optimize the water pump have been implemented since February 2014 in the engine production.” (Providing a larger reservoir?)
The situation with the magazine's R12GS was monitored, the goop cleaned off of the engine (which promptly returned) and then the bike was taken to the local shop for early maintenance at 5000 miles, at which time the entire water pump was replaced, which would have cost $380 if it had not been done under warranty.
So remember, if your water pump leaks, it is a carefully designed feature of your new water-cooler – just like the one at your workplace.