There are a whole lot of threads about the coolant level in the overflow reservoir. Why the level seems to drop quickly, without leaks. How to replenish the coolant. Which coolant to use. Which water to use. This thread is a summary of what the forum wisdom has offered. I forget who first posted the 3 Screw Method, but it works great.
1) The K1600 Coolant System
Our K1600 engine has a coolant system with a lot of nooks and crannies which trap air. So, if you have you bike worked on, water pump replaced, valves checked, etc..., you will have the coolant drained and refilled. This will nearly always lead to trapped air in the system. Air which will eventually, or quickly, depending on how you ride, come to the radiator, and drain your coolant reservoir.
Until all trapped air hits the radiator, your coolant level may, at anytime, drop.
2) Checking the coolant level. Fast, easy and a smart thing to do before rides.
From the front of the bike, look under the headlight, up and left. The little blue bottle.
![Image]()
![Image]()
![Image]()
3) Adding coolant, the easy way. 3 Little Screws Method
The yellow arrows point to the specific 3 screw screws. Just those 3 allow you to pull the top of the fairing out to gain access to the top of the coolant reservoir.
A - Locate and remove these 3 T-25 screws.
![Image]()
B - Pull the fairing top our and look down to the top of the reservoir. You will see the little black rubber cap. Stick your fingers down and remove the cap, careful to hang on to it.
![Image]()
C - Use some funnel with a long hose to get coolant/water into the open reservoir opening. 50/50 ratio.
![Image]()
D - Once refilled, carefully fish the rubber cap back down and onto the opening.
E - Replace the 3 T-25 screws.
F - Done.
If you are out on the road, on a nice ride, when you notice the low coolant level, my recommendation is to top off the level with water. Finding the right coolant is too much trouble, and there is nothing wrong with water. Such a small volume won't make any difference. With just your T-25, located under the seat, and a bottle of water, Aquafina is functionally distilled, you can dump it down and get enough in to refill the reservoir.
Which coolant? Why not something from the auto parts store?
There are now many different formulations of coolant available. BMW has a specific mix of chemicals which they feel is right for their engines, both auto and motorcycle. Mixing different coolant formulas is at best risky. You risk a chemical reaction which will damage the engine. Don't mix. Best to just get a gallon of BMW coolant and have it on hand at home.
![Image]()
Which water? Spring, filtered, tap or distilled?
Asking this is a good way to start an argument. Worse than which oil or tire. Let's just say that I have a gallon of distilled water in the garage.
If I'm on a long ride and the bike burped enough air to empty the coolant reservoir, I will use whatever clean water I have on hand.
Why, after the dealer works on the bike, does air get trapped in the engine?
Bleeding the K1600 engine of all air appears to be more than service techs are willing to do, because of the time it takes.
BMW added two bleeder screws to this engine. Many service techs don't open the one on the left side of the engine.
![Image]()
After getting my valves checked, I engage in some spirited riding, lots of twisty turns leaning the bike, and high revs, to expel trapped air. Then, check and refill the coolant reservoir.
Good Tip: Never have major service completed before a long ride.
Seems that many find that their cooling system burps while out on a long ride. Instead of buying a funnel, you might have seen my thread on hydration and purchased the inexpensive water bottle adapter.
![Image]()
Easily remove the drinking end and use the hose to add the necessary water to the coolant reservoir.
Multi-tasking. :gm
1) The K1600 Coolant System
Our K1600 engine has a coolant system with a lot of nooks and crannies which trap air. So, if you have you bike worked on, water pump replaced, valves checked, etc..., you will have the coolant drained and refilled. This will nearly always lead to trapped air in the system. Air which will eventually, or quickly, depending on how you ride, come to the radiator, and drain your coolant reservoir.
Until all trapped air hits the radiator, your coolant level may, at anytime, drop.
2) Checking the coolant level. Fast, easy and a smart thing to do before rides.
From the front of the bike, look under the headlight, up and left. The little blue bottle.
3) Adding coolant, the easy way. 3 Little Screws Method
The yellow arrows point to the specific 3 screw screws. Just those 3 allow you to pull the top of the fairing out to gain access to the top of the coolant reservoir.
A - Locate and remove these 3 T-25 screws.
B - Pull the fairing top our and look down to the top of the reservoir. You will see the little black rubber cap. Stick your fingers down and remove the cap, careful to hang on to it.
C - Use some funnel with a long hose to get coolant/water into the open reservoir opening. 50/50 ratio.
D - Once refilled, carefully fish the rubber cap back down and onto the opening.
E - Replace the 3 T-25 screws.
F - Done.
If you are out on the road, on a nice ride, when you notice the low coolant level, my recommendation is to top off the level with water. Finding the right coolant is too much trouble, and there is nothing wrong with water. Such a small volume won't make any difference. With just your T-25, located under the seat, and a bottle of water, Aquafina is functionally distilled, you can dump it down and get enough in to refill the reservoir.
Which coolant? Why not something from the auto parts store?
There are now many different formulations of coolant available. BMW has a specific mix of chemicals which they feel is right for their engines, both auto and motorcycle. Mixing different coolant formulas is at best risky. You risk a chemical reaction which will damage the engine. Don't mix. Best to just get a gallon of BMW coolant and have it on hand at home.
Which water? Spring, filtered, tap or distilled?
Asking this is a good way to start an argument. Worse than which oil or tire. Let's just say that I have a gallon of distilled water in the garage.
If I'm on a long ride and the bike burped enough air to empty the coolant reservoir, I will use whatever clean water I have on hand.
Why, after the dealer works on the bike, does air get trapped in the engine?
Bleeding the K1600 engine of all air appears to be more than service techs are willing to do, because of the time it takes.
BMW added two bleeder screws to this engine. Many service techs don't open the one on the left side of the engine.
After getting my valves checked, I engage in some spirited riding, lots of twisty turns leaning the bike, and high revs, to expel trapped air. Then, check and refill the coolant reservoir.
Good Tip: Never have major service completed before a long ride.
Seems that many find that their cooling system burps while out on a long ride. Instead of buying a funnel, you might have seen my thread on hydration and purchased the inexpensive water bottle adapter.
Easily remove the drinking end and use the hose to add the necessary water to the coolant reservoir.
Multi-tasking. :gm
