philanthropy74
Registered
Why would this be even a possibility? I don't follow the logic?
What feeds the fan switch relay with power?
- Thread starter philanthropy74
- Start date
That sounds like the relay is stuck in the closed position and feeding power to the fan motor continuously.
The thermoswitch is having no effect on the switching of the relay because the relay contacts are stuck on.
So try testing the relay using the test in the pic from the manual I posted up earlier.
Can you even hear the relay click when testing it?
I’ll try to post a diagram of the cooling fan circuit later.
Mr Brown
Registered
No, the temp sensor would see a higher temperature because a smaller amount of coolant wouldn't cool as efficiently.
Mr Brown
Registered
The cooling circuit doesn't have the ability to shut the bike down, something else is causing that to happen. As I said, vapor lock in the fuel pump is a known issue on the early bikes, so that's a likely cause.
@philanthropy74
When the relay is working correctly, it is switching the ground to the fan motor, and there is a permanent 12v supply to the fan motor.
It appears the only possibility I can see with the fault you have with this fan staying on, is a bad relay with stuck contacts.
Have you actualy tested the thermo switch continuity, hot and cold?
Have you tested the relay correctly as per the pic of the manual I posted earler?
When the relay is working correctly, it is switching the ground to the fan motor, and there is a permanent 12v supply to the fan motor.
It appears the only possibility I can see with the fault you have with this fan staying on, is a bad relay with stuck contacts.
Have you actualy tested the thermo switch continuity, hot and cold?
Have you tested the relay correctly as per the pic of the manual I posted earler?
philanthropy74
Registered
Yes, I have tested the relay and it clicks and clacks the way it should. This was done off the bike. How do I test the relay ON the bike?
Hayabusa Wannabe
Registered
Here is a test of thermostats. Start the bike cold. Put your hand on the radiator or for safety point a laser thermometer at it. The rad should remain room temperature until it hits the triggering temp, 180°F or so. It should then get roasting hot all at once (BE CAREFUL!)
If the rad slowly and continuously warms up then the thermostat is stuck at least partially open. If it stays cold the thermostat is frozen shut. This is a reasonable test, and while not perfect it is easy without any removal work or cost.
Last edited:
philanthropy74
Registered
I have replaced the thermostat and put the old one in a boiling cup of kettle water. The old one didn't open... so either my kettle is not as hot as I believe it is... or... that thermo has stopped working. I put the bike back together and it still ran up hot with fans either on full whack or not on at all. I think its the relay but my thermo switch isn't here yet so I'm still waiting for that...
Dopey
Registered
If the bike is running hot with the fans running constantly then you have other issues going on.
Hayabusa Wannabe
Registered
Is there coolant in the oil?
philanthropy74
Registered
Nahh, oil and coolant are good
philanthropy74
Registered
Update......
Until now, I was running the bike up with an Aux fuel tank (as my tank was having a repair)
Now I plumb the tank back in and put some petrol in and fire it up. The bike gets hot, the thermostat opens, radiator gets instantly hot... so I turn on the fan expecting the temp to drop. It does seem to drop (garage gets warm, real quick) and the coolant pipes do cool off.. but it then suffocates and stalls. Something appears to be turning the bike off. No dash lights, all seems well.... hmmm... I still don't have the thermo switch yet but why might the bike shut off even if the fan is on and cooling things down?
Until now, I was running the bike up with an Aux fuel tank (as my tank was having a repair)
Now I plumb the tank back in and put some petrol in and fire it up. The bike gets hot, the thermostat opens, radiator gets instantly hot... so I turn on the fan expecting the temp to drop. It does seem to drop (garage gets warm, real quick) and the coolant pipes do cool off.. but it then suffocates and stalls. Something appears to be turning the bike off. No dash lights, all seems well.... hmmm... I still don't have the thermo switch yet but why might the bike shut off even if the fan is on and cooling things down?
philanthropy74
Registered
Second update, I've shorted the diagnostics plug and the dash reads c00. No codes apparent. I also noticed that the fan is now OFF. When the tank was off, the fan was on all the time. Must have been to do with the fuel level sensor being disconnected. The fan is now off and wont come back on! Ha ha, the bike is trolling me!
well, that is a learning curve right there . . . who would have thought having the fuel sender unplugged would have upset things lmao.
philanthropy74
Registered
***UPDATE***
Okay, I have now fitted my thermo switch and fired it up. The bike started to get warm and before the thermostat opened, the fan fired up... but on a cold radiator... which I don't think is an issue really (is it? ) but the bike started to get warm, the fan did come on (this seems to be fixed) and when the thermostat opened, the radiator got nice and hot instantly. All appears good... but the gauge seems to be reading just below half... which I am okay with, seems reasonable... but the bike then cuts out and wont restart as if its over heated. I can only assume the temp gauge isn't reading properly and the cylinder head mounted temp sensor is kicking in to turn off the bike? The bike is at operating temperature at this point. Not losing any coolant through the exhaust or through the plumbing... the bike is dry and the coolant is staying in, the fan is on and working.. but something still appears to be knocking the bike off.
Is there any specific bleed points? It's acting like its an air lock... I feel the thermo switch did do something positive... the fan does appear to be controlled now. If this isn't air locked some how, what else could cause it to seemingly over heat? It doesn't SEEM as hot as it should be to knock it off but I may have to change the cylinder head sensor. Any specific bleed points? I do have a Flir camera, that's my next attack but I was hoping for a electro-mechanical solution before I got to the Flir...
Okay, I have now fitted my thermo switch and fired it up. The bike started to get warm and before the thermostat opened, the fan fired up... but on a cold radiator... which I don't think is an issue really (is it? ) but the bike started to get warm, the fan did come on (this seems to be fixed) and when the thermostat opened, the radiator got nice and hot instantly. All appears good... but the gauge seems to be reading just below half... which I am okay with, seems reasonable... but the bike then cuts out and wont restart as if its over heated. I can only assume the temp gauge isn't reading properly and the cylinder head mounted temp sensor is kicking in to turn off the bike? The bike is at operating temperature at this point. Not losing any coolant through the exhaust or through the plumbing... the bike is dry and the coolant is staying in, the fan is on and working.. but something still appears to be knocking the bike off.
Is there any specific bleed points? It's acting like its an air lock... I feel the thermo switch did do something positive... the fan does appear to be controlled now. If this isn't air locked some how, what else could cause it to seemingly over heat? It doesn't SEEM as hot as it should be to knock it off but I may have to change the cylinder head sensor. Any specific bleed points? I do have a Flir camera, that's my next attack but I was hoping for a electro-mechanical solution before I got to the Flir...
Hayabusa Wannabe
Registered
Did you see @Mr Brown's post? Also once it has shutdown open the gas cap and check for vacuum that may be holding fuel back, ergo that there is no inrush of air when you open it. Make sure no lines are kinked under the tank.
Check that the main ground is attached. Put a DC voltmeter on the battery and monitor the voltage before just before it begins to sputter.
Check that the main ground is attached. Put a DC voltmeter on the battery and monitor the voltage before just before it begins to sputter.
Last edited:
philanthropy74
Registered
I have just realised the thermostat is sided. There is a bleed hole in the top of the thermostat. I might have put it in upside down... gunna have to check that now...
philanthropy74
Registered
I have seen it yes and I will try what you suggest but I don't think that's the cause. I don't see any logical connection to the suggested solution and the symptoms I'm having.
philanthropy74
Registered
Just checked the thermostat, it was 90 degrees out. The bleed screw was at 3o'clock rather than at 12 oclock. That is now correct. The bleed hole is in the correct position. It didn't make any change, the bike still cuts out upon test. What I noticed is when the bike does it's temp gauge fire up, the temp indicates it's much higher... hmmm....
Similar threads
