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Coolant / radiator fluid change on a Kawasaki Vulcan Nomad 1600

We metric riders brag about riding liquid-cooled bikes, but how often do we replace the liquid? About ever year or two we really ought to consider swapping out the fluid, especially because it's so easy!

What type of fluid can be used?
Honda makes a motorcycle specific coolant, but any coolant safe for aluminum body radiators should be fine. One thing to keep in mind is that it's not good to mix dexcool (orange coolant) with the green, standard coolant. It's a common complaint that mixing these two products can cause a gummy build-up inside the radiator and reserve tank.

1. Place a container under the radiator and remove the bolt on the bottom of the radiator, catching the rubber washer from falling into the fluid.
2. Remove gas tank.
3. Remove radiator cap, which is located on the right side of the frame about half way down the spine.
4. Remove the right side cover to access the reserve tank. Remove the reserve tank and drain old fluid. If you notice residue build-up, now would be a good time to clean it thoroughly.
5. Replace bolt on the bottom of radiator and reserve.
6. Fill from the radiator cap, shaking the bike to bring any air bubbles to the surface, until completely full.
7. Fill reserve to the full line and check levels. If everything is still full, replace the tank and side cover.

That's it! Easy, wasn't it?

For the most part, this is the same process for any bike.


  1. Thank you Jared! Straight forward and easy to follow! What type of coolant do you use?


  2. my coolant will not stay in the side container. Assuming it overflows on a hot ride. Where is it going? It sounds like it is boiling when I turn it off for a few minutes. Got any ideas?

    1. Having a similar issue myself, for the second time in two years ('08 Vulcan Classic 1600). I noticed the fan wasn't coming on as regularly, or at all anymore, causing the bike to overheat and burble like it was boiling, particularly at stop/idle. On a nice run through the mountains, we stopped for a few mins to layer up, my bike was still idling, and my coolant boiled up and ran out the reservoir tank overflow hose underneath the bike. I replaced the fan switch last year at about about the 18-20,000 mile mark. That fixed the problem then, but it appears the same is happening again (guessing only about 6-8,000 miles later). My buddy just had the same thing happen to his 1500 too, so maybe it's just a Vulcan thing. Big motor + small radiator = lots of action for the fan, and maybe it just wears the switches out. Certainly hope it lasts longer this time around!

      If your fan isn't coming on, check the fuse first by the coolant reservoir. If that is ok, and to confirm it is a fan switch issue, not a problem with the fan itself, here's what I found online:

      1. unplug the fan switch
      2. put the ignition key in the run position
      3. use something to cross the wire poles on the fan plug itself (I used a u-shaped bent paper clip to touch both simultaneously).

      If the fan comes on, the fan itself is ok and the culprit is likely the fan switch. It's either not working at all, or not in the right temperature range to engage the fan before the coolant overheats.

      To double check mine, I plugged the fan switch back in, then started the bike and idled it for a few mins. The fan didn't come on at all, and the coolant boiled over again = faulty switch. Hope this helps you out, and saves you some google troubleshooting time!

    2. Update - Turns out it was a simple radiator cap issue, not the fan switch this time. Rad cap was sealing properly, so the bike was letting coolant out into overflow reservoir at too low of a pressure. New rad cap and the problem seems to be solved.

  3. ...not sealing properly I meant.