Manual Testing of the Radiator Fan

[Descolada]

Hi All,

Does anyone know if it's possible to perform a manual test of the radiator fan? I assume that the fan is triggered by the temperature sensor mounted on the radiator, once it reaches a pre-defined temp it closes the gap on the connectors thereby powering the fan. I also assume that this is some sort of bi-metalic or wax controlled switch.

Is it possible to bypass the temp sensor and short the pins in the connector (to mimic the sensor closing the circuit) in order to test the fan, or will this just result in the magic smoke somewhere?

I had the radiator assembly out for repainting recently, and although the fan does turn freely it doesn't seem to "free wheel" as much as I expected. I want to confirm that it is still working without having to overheat the engine.

Anyone done this before?

[locksim]

Should be easy enough - most people used to fit bypass switches on GPz900Rs to prevent the boiling problem they had - I'd imagine you'll get the fan to spin up by applying 12v.

Simon

[King Orry]

I once used a piece of wife from the cellar of the Creg ny Bar pub to 'hot-wire' a pals rad on his Honda Hornet up to his position light. The sensor had failed and he was boiling over when coming off the IOM ferry. I connected it so it came on when he turned his lights on. Worked a treat.
In fact, it was still in place when he sold it a couple of years later.!
 

[UK_Vstrom650]

I once used a piece of wife from the cellar...

 

[Descolada]

I once used a peice of wife from the cellar

Crikey! You're a dedicated bloke. Can I ask, what piece did you use and could she still function without it? 

[greywolf]

Unplug the radiator connector, turn on the ignition and short the wire connector contacts together with a piece of wire. If the fan doesn't come on, check the fan wire connector on the radiator top shroud. That's the usual problem followed by the fan blade being mechanically impinged by its shield. If the fan runs in the test but the temp gauge sometimes gets to four bars or more, in stop and go traffic especially, you can take the fan switch out of the radiator at test it for electrical conductivity in boiling water.

If the temp gauge exceeds 3 bars in clear traffic, the problem is not the fan but possibly a clogged radiator, internally with sludge/scale or externally with dirt/bug bodies/mud/etc.. Other possibilities besides a clogged radiator are a stuck thermostat, lack of coolant or a clogged water passage/hose.

[Descolada]

Thanks greywolf. I'm really just checking it for my own piece of mind following the respraying work and rebuild (comlete with coolant change). Just took it for a wee spin and the temp never went above three bars. I'm still waiting for the cooling system to 'belch' following the drain and refill.     

[greywolf]

You can let the bike idle to make the fan come on before 4 bars to check it. 3 bars is normal for a 650.

[King Orry]

Crikey! You're a dedicated bloke. Can I ask, what piece did you use and could she still function without it? 

Bloody Yank Spell-Checker strikes again..! 
However, I will add..
Those under-wired bra's can be a proper toolkit.. in the right hands ;-)