Boiling antifreeze - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 3 (permalink) Old 01-30-2018, 08:06 PM Thread Starter
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Boiling antifreeze

I started spelling antifreeze after my bike fell over when someone bump it while on its stand. I look for any signs of leaks and canít find anything. Iíve had to add some but very little to it like four times now. Fans r running. I tried changing the cap. Did notice while pulling it apart there is sighns of dried up antifreeze around cap. Which makes me think more itís boiling but why.
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post #2 of 3 (permalink) Old 01-30-2018, 08:44 PM
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Was it knocked over on the left side? Your coolant reserve tank is on that side. Maybe cracked it?
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post #3 of 3 (permalink) Old 02-01-2018, 03:37 PM
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Use a flashlight to check hoses to the radiator(s) for signs of coolant residue.
The hose clamps can take a set over time and allow coolant weeps, and may need to be tightened.

Also, check around the lower parts of the side cowls for coolant residue, and while at it, reach in and manually give the fan(s) a spin with your finger (engine switched off and cool, of course).
The fans should spin freely, with no signs of rubbing against the radiator.
If the fan(s) do not spin freely, or make squeaking noises, then the fan motor bearings have failed or are failing, and should be replaced.

If the fan blades are rubbing against the radiator, check if the radiator mounts are bent and straighten if needed.
Since the radiators are mounted on the sides, if the bike fell hard enough, it may have bent the radiator mounts.
And if this is the case, check the radiators for cracks in the housings or passeges.

The coolant overflow tank should not be full, but between the low and high marks.
If overfilled, it can spill through the rubber cap and down the sides.
Also, make sure the overflow tank hose to the radiator is not pinched.
Clean the area around the radiator cap, and if residue is seen afterwards, then the radiator cap may be weak and need replacing.
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