ER5 radiator fan.

I noticed when pootling through London traffic, stop starting a lot,
that my thighs felt a bit warm. I haven't seen the radiator fan spinning
once since then.

I have checked the fuses visually, and they seem in perfect nick, but
I'll continuity test them properly in a bit. Since I'm sitting with a
cup of tea in the warm at the moment free to consider theory, what else
should I be looking at sternly and fundamentally how can I test the
operation of a thermostat operated bit, rev it till steam comes off?

I can, plonk 12V on the motor and see if it spins. I can continuity test
the wiring any place I find a metal bit to pop a multimeter on.

Is there anything I can do with the thermocouple screwed into the rad.?
unscrewing it would get me wet feet I suspect.

Ta.

 

You should be able to check all of the wiring in one hit by just
unplugging the connectors from the thermocouple and joining them together.

Make sure you have plenty of water - on some designs low water means the
fan never comes on.

Failing that then you need to test the thermostat, either by revving the
bike until it gets hot enough (but keep an eye on the gauge), or by
removing the switch and testing it in boiling water.

 

How hot was the engine getting? I've generally found fans don't cut in
til about 100 deg C.

 

Indeed. Nordwests are prone to failure of the fan sensor and it is
always easily checked thus.

<Remembers GFR disaster>
And a false reading on the temperature gauge. Though the sensor for that
was on the head rather than the radiator.

I used a small rubber bung to fill the orifice when testing the one on
the Nordwest engined Saturno. It was fairly critical that it operated at
a reasonable temperature as the guy who built the bike had removed the
radiator cooling fan in order to get the twin-pipe Nordwest motor in. So
the sensor was just connected to an "if I had a fan it would be coming
on now" light. It was a flashing LED which drew the attention reasonably
well. Failing that, as it also had no header tank, the dribble of
steaming blue liquid on to my right boot if caught at traffic lights for
a while after a sustained making of progress got the message across.

The Voxan runs very hot and the fan cuts in under the slightest
provocation. I'd be in hot water if the sensor on that failed. Except
that I wouldn't be immediately as it has retro-fitted expansion tank.


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| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest * 2 Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
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