Hot Bike!

Got a weird one...

Bike was getting extremely hot today. While running the cooling fan was kicking on and off like normal. What I notice was odd (aside from the bike just seeming hotter than usual) was even if the fan was currently running while the bike was running, if I shut off the bike the fan quit (ignition still on). Of course, with no fan running the engine temp gauge was maxed out. Usually the fan continues to run even if the bike is off so long as the ignition is on and the thermal switch says "HOTTT!!!". Bad thermal switch???? Why would the fan care whether the bike is running or not?

Your consideration in this matter is greatly appreciated. I will drink Sierra Nevada and ponder this problem. Cheers!

 

? my bikes, if the fan is on and I turn the key "OFF" the fan stops. My Kawasaki, if you turn the key "OFF" and take the key oot of the ingnition and walk into the sleaze bar, the fan continues. Hondas are different, what can I say, sometimes I think the H in Honda is for "HASSLE" anyway, dats all me knows aboot this here so called problem.

Cheers :vtr2:

btw I don't know if you left the key in with the power on but the engine off if the fan woud continue.

 

I installed a manual switch on the fan, because in 90+ heat here, temps skyrocket at long traffic lights and riding at 35 or less in town. When you shut the engine off, water stops circulating, fan will cool water in one radiator but not engine. If I leave my fan on after engine stops, temps don't go down very fast. If engine is hot when I stop, then I let engine run with fan on for a couple of minutes to prevent "heat soak", to even out heat dissipation. Jet airplanes do the same thing, they let engines idle to cool down and even out temps.

Remember, cooling systems are pressurized by caps, allowing coolant to get hotter than 212 degrees and not boil, that why you never take cap off when an engine is hot, decrease in pressure will lower boiling point. Check your levels and cap.

 

I'm going to step outside my cognitive abilities here and suggest some sheeeeeit...

The position of the radiator and fan assembly, being higher in relationship to the engine location, and the nature of a closed cooling system would circulate the coolant based on the laws of thermodynamics????

...my head just farted.

The radiator fan has to have two things satisfied to run...
1) Key (ignition) in the ON position.
2) Thermal switch is in the Closed position.



Either it's the fan motor, the mini connector or the thermal switch... guess it's a process of elimination.

 

Faulty thermal switch (Fan motor switch)

 

so how did you do it? test light? Process of elimination is usually the way it goes. :thumbsup:

 

Yep. Grounded out the female spade terminal that connects to the thermal switch and the fan runs fine. I can only assume that the thermal switch is requiring higher and higher temps to close the bimetal contacts.

 

Cars will continue to run the electrik fan if engine temps are high, but bikes DO NOT. Ignition off, fan will be off too.

 

Yes but ignition on,motor not running, temps high... fan should run.

 

Except for maybe the Buell 1125R. OCLandspeeder has one and the fan stays running with the bike turned off.

 

It's the thermal switch... and yes a vfr750 should continue to run a fan after the engine stops so long as the key is in the on position and the thermal switch calls for fan-age. Is this horse dead or should we continue to kick it? Jk

 

That avatar is from Ren and Simpy is'nt it? ound:

No need to drag it through the embers anymore.

 

I'm more of a muddy mudskipper fan m'self


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Ohhhh shite... She's running super hot. I put a switch on the fan and ran it periodically... But when i pulled into the drive she was burnin up! the fan couldnt keep the temps down. Oil smells funny too. Im going to drain it and do an inspection. I could be in for a motor rebuild if it's blown a gasket... Time to get that frame powder coated like i always wanted. Would an exhaust leak sky rocket the temps like that?

 

Sounds a lot like a head gasket. Is the oil the color of a chocolate milkshake?

 

Got to let it cool down for a while before i bleed it... it was that hot. Time to sit back and enjoy some Guinness in a can. It is Friday, you know.

 

Bingo!

"Children, clench tenaciously to my buttocks!" PTM

 

Looks like oil...

 

Definitely no water in oil! Thermostat not opening completely? Cap OK?

 

Could be... Going to look through it later today. When the bike got super hot (30 mins of traffic riding) it lost all low end power. Ive suspected exhaust leaks mainly because of hot much she pops and crackles on ROffT. Maybe improper carb settings??