Changing Coolant in your VN750
I have an 01 VN750 with over 31,000mi on the dial. I changed my coolant LY for the first time @16000mi and again this year when I replaced my stator @25800mi. Some notes for those who might be thinking about this...
Things you'll need...
Torque wrench, 10mm and 12mm open ended wrench and sockets, phillips screw driver, Anti-freeze/coolant (silicate free for aluminum engines), 1/2gal of distilled (not spring or tap) water from a new bottle, a clean drain pan, empty container for used coolant and various rags.
1. Put the bike on the center stand. Do not run the engine...this maintenance is done with the engine COLD!
2. Drain pan under right side of engine block.
3. Remove the right side plastic cover that covers the radiator cap near the steering head. It's held by 2 phillips screws top and bottom. Loosen the radiator cap. Mine was 'constrained' by the throttle cables, but you can firmly move them out of the way. Make a note of how they run behind/around the cap before you move them.
4. Remove the drain plug under the right side of the engine block. It's the 10mm bolt that is closest to the right side edge of the crankcase on the bottom. If you have a drain pan that is long enough, you can also drain the radiator at this time by removing the radiator plug & gasket (bottom left on radiator cover as you look at it) w/ a 12mm socket.
5. Remove the reserve tank near the right side cover. Remove the 2 hoses (have your rags ready) and clean out the tank w/ a bottle brush & mild soapy water. Rinse thoroughly!! and re-install.
6. The crankcase should be done draining by now, so replace the plug after inspecting the crush gasket (replace if worn). Tighten to 78 in/lbs.
7. There are 2 10mm cylinder drain bolts. The front cylinder plug is on the right side of the bike, below the spark plug and under the cooling fins. The rear cylinder plug is on the left side below the spark plug and under the cooling fins. Before you remove them, stuff some rags in the engine cavities under the bolts to catch the coolant. There won't be alot, but it will go everywhere...
8. If not already done in step 4, remove the drain plug from the radiator and let it drain. While it's draining replace the cylinder drain bolts. Torque to 78 in/lbs. If you performed the radiator drain in step 6, replace the drain bolt and gasket. My Clymer's says torque to 26 in/lbs, but I used 30.
9. Inspect the condition of the old coolant. Clymer's or the VN750 tech manual will give you good direction as whether you need to flush the system or not. If you need to flush & rinse the system, do it now by following those instructions or the instructions on the radiator flushing product you will be buying.
10. You're ready to fill the system! Slowly fill the radiator with a maximum 50/50 percentage mix of coolant and distilled water. 'Slowly ' minimizes the air that will be trapped in the system. Fill to the top of the radiator cap inlet on the filler neck...just to the point where you can see the solution. Add the same mixture to the 'Full' mark on the coolant tank.
11. Loosen the air bleeder bolt on the thermostat housing. It is a 10mm bleeder bolt that is immediately to the left of the radiator top (where you just poured your coolant) just under the fuel tank. It looks just like the ones on the brake calipers. You don't need to remove the tank, you can get to it just fine. Put a rag under under it for the next step.
12. Continue to add coolant/water mix to the filler neck and watch the bleed valve. Add mixture until the the coolant flowing out of the valve is free of bubbles. Mop up your mess and tighten the valve to 69 in/lbs if you get your torque wrench in there. Top off the radiator to the bottom of the filler neck. Replace, but don't tighten, the filler cap just yet. Check for leaks at all drain plugs.
13. Start the bike and let it warm up a bit, ~3min will do fine. Remove the filler cap, and rev the engine gently but firmly to 3000~3500rpms while watching the filler neck of the radiator. You probably will see bubbles escaping, which is OK as they should dissipate in time. You might also see the coolant level receding into the radiator..top off with more mixture. If bubbles persist, shut off the bike & repeat steps 11~13 after the engine has cooled.
14. No bubbles?? You're done..for now!! Tighten the cap (watch those throttle cables), replace the cover, clean up your mess and go for a test ride. When you get back, check coolant levels at the reserve tank and filler cap when cold and re-adjust if necessary.
Congrats!...you've mastered another pesky maintenance item!