coolant problem - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 5 (permalink) Old 07-23-2012, 06:50 PM Thread Starter
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Exclamation coolant problem

Hey all,

I have a 2000 RC51 that pumps water into the coolant overflow bottle every time I am on the gas hard. My ridding buddies noticed a white misty plume of what they thought was smoke. Only to find out it is coolant spraying on exhaust in lower fairing. Friend of mine said Rad Cap was faulty but , is new and rated at 16lbs. So I purchased another rad cap a 20lb unit and tried again, still pumps water out into bottle at high rpms and vents thru hose to cowling. Bike has all new hoses , thermostat, water pump and new rad cap. Bottle is full of fluid to neck when I service water level in radiator bleeding system per Manual. Am I over servicing? Buddy also suggested that I may have a blown head gasket and bike is pumping combustion in to water jacket, could this be? Bike runs extremely well , temp runs around 175 when just cruising. When on the gas and at high RPM's bouncing off rev limiter she runs around 190-200,215. Any of you Bad ass RC51 riders got any ideas what is wrong??
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post #2 of 5 (permalink) Old 07-23-2012, 07:48 PM
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With no overheating issues, and a new radiator cap, I'd say it sounds more like a head gasket issue.
Does the coolant smell like fuel or such?
And what does the oil look like?
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post #3 of 5 (permalink) Old 07-23-2012, 08:57 PM Thread Starter
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Hi sub , Thanks for the reply. Coolant does not have any unusual smells and oil is clean. I changed oil and filter just prior to this problem and no water contamination at that time. I am prob going to have to press ck the system have not done that yet.
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post #4 of 5 (permalink) Old 07-23-2012, 09:54 PM
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Might have a radiator leak. Have you had the fairing off to look at them?

John, 2000 RC51 #000100

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post #5 of 5 (permalink) Old 07-23-2012, 10:24 PM
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Cooling system pressure is overcoming the radiator cap spring or these new caps are not sealing properly. Pressure check will confirm this. Your tubing to the overflow bottle is probably leaking, due to the pressure also.
Ensure that the radiator cap fits and seals properly in the filler neck housing.
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