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Discussion Starter · #1 ·
My 1993 ex500 that I recently engine swapped is now back in full swing with a new issue. It overheats, and the temp gauge is consistently reading at the H or slightly below it. I was able to get it home without anything serious happening and noticed my fan isn't turning on. I took the wire that connects to the switch on the radiator off and bypassed it with the ignition on to see if the sensor was bad but the fan didn't come on at all, I checked the 10amp fuse and it looks fine. Does that indicate that the fan is bad or is there something else I should look for?
 

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hi, I took mine out this afternoon for a shakedown run and to scrub in the new rear tire, after passing the MOT this morning. nice day +17deg C went steady the first 30miles then truly hammered it for the next 60.
the temp gauge never went above 1/2 and of course the fan never came on, this is normal for this bike.
If yours is getting so hot it suggests a cooling issue, did you bleed the cooling system to get all the air out is the coolant circulating properly. pump working as it should. if it is and it's just a fan issue try the same test on the fan connector direct to see if the fan is bust. if the fan runs when wired direct try shorting the two switch wires.
your going to have to fault diagnose the whole cooling system the engine should not get that hot even if the fan fails normally the air flow through the rad is enough to keep the engine a stable temperature, as mine did today.

edit, and don't forget to check the gauge sensor sometimes it's just a faulty reading.
 

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But it's also normal for it to get hot enough for the fan to come on if you get locked down in traffic, or get stuck at red lights for too long.
 

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I recently changed the water temp sensor like yesterday. Could I have a bad connection somewhere? where should i look for the wires
there is only one the yellow and red one on the end of the switch earth that wire out the gauge should peg out full but if the gauge starts off cold on a cold engine it may be ok. I once had overheating on a car but it wasn't overheating the gauge sensor was faulty. (IE reading too high for a given temperature) that's what I meant.

How would I go about bleeding the cooling system?
you do this when filling the coolant, fill the expansion to about about 2/3rds, take off the pressure cap and fill with coolant then squeeze all the coolant pipes starting at the btm until all the bubbles are gone keep filling and squeezing until there is no air present fill the right to the top of the cap and refit run the engine on a fast idle until it warms up check all the pipes for leaks. and they are warming up and pressurised.
once up to running temp or when the fan comes on and stops (1cycle) turn off and let it cool down this will set the expanded coolant back into the system. just make sure the btm rad hose is the same temp as the top one when warm.
 

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Discussion Starter · #8 ·
there is only one the yellow and red one on the end of the switch earth that wire out the gauge should peg out full but if the gauge starts off cold on a cold engine it may be ok. I once had overheating on a car but it wasn't overheating the gauge sensor was faulty. (IE reading too high for a given temperature) that's what I meant.


you do this when filling the coolant, fill the expansion to about about 2/3rds, take off the pressure cap and fill with coolant then squeeze all the coolant pipes starting at the btm until all the bubbles are gone keep filling and squeezing until there is no air present fill the right to the top of the cap and refit run the engine on a fast idle until it warms up check all the pipes for leaks. and they are warming up and pressurised.
once up to running temp or when the fan comes on and stops (1cycle) turn off and let it cool down this will set the expanded coolant back into the system. just make sure the btm rad hose is the same temp as the top one when warm.
my gauge sensor is fine. and my fan works when directly hooked to the battery. could the connector to the fan be faulty?
 

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anything is possible that's what diagnostics are for, to eliminate what is working. and detect what isn't.
when all other possible issues have been eliminated. whatever is left has to be the issue.
 
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