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Engine Temp @ 100C aka 212F @ 100KM/hr aka 60M/hr


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Hi Ya'll,

 

Anyone have ideas on how to diagnose a 'hot' engine?

 

'99 5th gen.  is running close to a temp of 100C at highway speeds (95-99C) aka 212F.

 

I know it's no cause for alarm as it's a ways away from the max, however, usually this time of year (27C aka 80F ambient) it runs between 78-85C aka 172-185F.

 

The other weird thing is that the coolant reservoir was empty after I had filled it a few days ago.

 

Here are the symptoms:

 

- Before I noticed the higher temps - I saw it was low on coolant.  I filled it (using Honda brand coolant) in between the lower and upper lines when the bike was cold.  After filling, the next ride it leaked a ton of coolant in stop n go traffic (another rider pointed it out).  Figured I put too much in and the bike would find a happy balance on it's own.  

 

The next few days I noticed the higher temp at highway speeds.  I checked the coolant level again - this time - dry as a bone.  How?  Why would the bike leak out the entire reservoir? 

 

Oil level is fine (was changed a few weeks ago).

The fins on the rads look okay but haven't taken the fairing off to get an up close and personal look.

The fan kicks in at the correct temp and is working fine.

 

What else should I be checking?  

What explains the coolant levels of first overflowing and then being empty?

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I would check your rad cap and if that doesn't work check the weep hole on your water pump to see if it is leaking past the seals.  If both of them are good check your thermostat. It may be stuck closed or just partially open

 

good luck and post once you find the problem

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Easiest first is radiator cap if the radiator cap is buggered then it won't be maintaining the system pressurised and the coolant will boil at a lower temperature if it boils it overflows if it overflows then the overflow tank and radiators will be partially empty. So there you have it the system is empty precisely because it has overflowed and it has overflowed possibly because of a dodgy radiator cap other reasons could be as mentioned a thermostat that has stuck closed but that's more hard work perhaps the water pump has become blocked and isn't spinning but normally they will start to leak so after changing the radiator cap the next thing to do is fill it up with fluid and perform the Purge procedure to Purge out any possible air trapped in the different nooks and crannies of the system if there were air trapped in the system it will expand to a much greater volume than the liquid will when heated up and this will displace your liquid coolant and make it overflow so first radiator cap then do the air purging procedure or what they called burping and if that doesn't fix it then start looking at thermostat and water pump.

 

The procedure for purging air from the cooling system is in the workshop manual which you can download from the download section on this forum

 

 

 

 

 

 

 

 

 

 

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I had similar symptoms with my 99, after running in stop and go traffic  in hot weather it would subsequently run hotter than normal even at speed and the coolant would be low. I finally found a pin hole leak in the overflow hose that runs from the radiator cap to the reserve tank. It had been rubbing against a metal part (the valve cover IIRC) and apparently the vibration rubbed a hole in it.

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7 hours ago, RolandHTG said:

I had similar symptoms with my 99, after running in stop and go traffic  in hot weather it would subsequently run hotter than normal even at speed and the coolant would be low. I finally found a pin hole leak in the overflow hose that runs from the radiator cap to the reserve tank. It had been rubbing against a metal part (the valve cover IIRC) and apparently the vibration rubbed a hole in it.

that's why it's always smarter to check under the rad cap and refill there rather than filling at the overflow bottle when coolant seems low.

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  • 7 months later...

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