[Russg]

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I've put in a new fan thermostatic switch. I shorted the thermo switch wire
with the ignition on and the fan comes on, so the fan is working. The fan will
not come on with the temp gauge well in the red zone, engine running.
I tested the old and new fan switches on the stove in antifreeze and both
come on at about 220 F, off about 180 F. I know the fan wires, one is blue
is hot when ignition is on, the therostatic switch supplies the ground to the fan,
a black wire. It acts as if there isn't a good contact of the switch prongs
and wire sockets, but I did test the wire sockets by shorting and fan came
on, ignition switch on, I already said that.
Any help appreciated.

 

[k1w1t1m]

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It sounds like your temperature guage might be inaccurate. Do you have a temperature reader that you can use to verify engine temperature?

 

[Russg]

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Hi, Tim.
I believe I may have the situation. The fan switch
is outside the thermostat. The temperature sensor
is inside the engine from the thermostat. So, I believe
the thermostat is failing to open.
That sound right?
I believe the temp gauge is right.

 

[k1w1t1m]

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I had to go and look...

Yes you are correct. The guage sender is on the engine side of the thermostat and the thermoswitch is on the radiator side of the thermostat.

I think you're onto it.

 

[taffallan]

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remove thermostat and run without it see what happens. Is your fuel gauge reading high? If it is then the 7volt regulator is naff replace it the switch makes at 98 - 102 degrees c run the bike to that temp can take some time.

Taffallan

 

[Russg]

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Thanks Taffallan and Tim.
That's one thing I might do, take thermostat out and
see if the engine runs cool, takes long time to heat up.
I took the thermostat out, I'm a little reluctant to
put the cycle back together to see if that solves the
problem. I will stove test the thermostat. Running
without the thermostat in will also test the water pump,
which is about the last thing it could be. I'm hoping
it is the thermostat, I already bought one.

 

[Russg]

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Oh, the gas gauge reads about right, it is pretty
full, reads about 4/5-3/4 full. The temp guage seems
to be functioning properly, as it starts out low and
slowly rises into the red, doesn't rise to the top
right away, long after the fuel gauge stops.

 

[Russg]

imported post

Oh, the gas gauge reads about right, it is pretty
full, reads about 4/5-3/4 full. The temp gauge seems
to be functioning properly, as it starts out low and
slowly rises into the red, doesn't rise to the top
right away, long after the fuel gauge stops.

 

[Russg]

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Well,
The thermostat tests good on the stove. Opens about 180
to full open at 200. That just leaves the water pump.
I guess I'll have to take it off and give it a look
tomorrow. I did try to push the impellers with my
fingers, but they only moved a little bit. I guess
the shaft fits in a socket of some type, and maybe the
shaft is busted. Anybody know?

 

[JBz]

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ive seen the shaft busted on a 75 if that helps. jb

 

[Russg]

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I removed the water pump. It seems to be in good
order, the sloted drive shaft is intact. I don't want
to disassemble any more, I'm getting too deep into the
engine. I just don't know why the cooling system
isn't working, thermo switch, termostat, temp gauge,
now the water pump, all seem OK.