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Discussion Starter #1
Is there a way I can check if my fan is working? I can't hear it kick in, and I have tried the trick of killing the engine with the killswitch then turning it back on, and I can hear no fan.

I don't want to go through the ride home after the bike piss*d coolant all over the road after 3 traffic lights. Probably a case of being overfilled but still, 112 celcius can't be right.

As a side note, where do you UK riders get water wetter or engine ice in the UK? Do you trust the eBayers? Is there a trusted brand, like this one?
 

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I can't remember about the Evo3 because I only had some brief rides on one, but on my early F4 750 the fans would still run with the engine not running. My 312, no; but the old 750, yes. If you're at 112C and the fans aren't on, I'd say they're definitely not working right.
 

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you could take off the coolant temp sensor and ground it to see if the fan comes on. that will let you know if the fan functions or not. no big deal changing out the sensor if necessary.
 

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i would just turn the bike with a faring off. Wait a few mins and let the temp climb......watch to see if the fan turns on or not. If you hit 210 or 215 with out the fan coming on then its not working
 

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I can hear when my 750's fan comes on. And I can feel the air being blown through the fairing. (Though not in leathers.)

If you can't tell the fan's running then perhaps it's not. It's obvious to me when mine is.

Try Demon Tweaks for Water Wetter, but don't expect it to make any difference..

Si
 

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My fan keeps stalking me :king: so I guess she doesn't work :jsm: :later:
 

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Maximum Velocity said:
My fan keeps stalking me :king: so I guess he doesn't work :jsm: :later:
That's a good one. :laughing: :laughing::laughing::laughing:
 

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112 is way high. i've never seen over 102.


my evo3 kicks in somewhere in the early 90s or late 80s. i know it works cuz when i get home it warms up in the city, so by the time i turn it off, i can hear the fan.
 

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Discussion Starter #13
Maximum Velocity said:
My fan keeps stalking me :king: so I guess he doesn't work :jsm: :later:
WAHEEYYYY! badum tish! :naughty:

I have checked the fuse, but not that the fan wiring is not melted by exhaust. If this is the case would an underseat heat tray protect the wiring? Haven't ahd time I must do this tonight
 

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style_one said:
too bad it's not a *she* fan. :jsm:
You know... that was the easy part. So changed the post :naughty:
 

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How have you got on with this, i have discovered this weekend that mine have packed up, i have done the usual checks (connector and fuse) and replaced relays but no luck, i was going to chase the wiring through next........
any help would be appreciated

Cheers
Chris
 

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Discussion Starter #16
style_one said:
you could take off the coolant temp sensor and ground it to see if the fan comes on. that will let you know if the fan functions or not. no big deal changing out the sensor if necessary.
Knowing nothing about electrics, how do I ground the sensor? The fuses are good, the fan itself will move freely if I push it, and according to the workshop manual the fan should come on at 92C

the official workshop manual said:
:FAN THERMALSWITCH
The cooling fan, positioned behind the radiator is auto-
matically controlled by the thermal switch. This switch
remains open when the temperature of the coolant is
low and it closes when the temperature of the coolant
reaches approximately 92°C thereby activating the fan.
have been renovating the house so haven't had a chance to look at this until yesterday - must solve this before weather gets good again!

:drummer:
 

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Helvetica said:
Knowing nothing about electrics, how do I ground the sensor? The fuses are good, the fan itself will move freely if I push it, and according to the workshop manual the fan should come on at 92C



have been renovating the house so haven't had a chance to look at this until yesterday - must solve this before weather gets good again!

:drummer:
Only EARLY 750's WITH ONE RAD worked this way, later bikes worked off the ecu, The switch in the rad is for the temperature display in the clocks. Early bikes had two sensors in the rad tank, one for fans, one for clocks
 

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EVO Chris said:
How have you got on with this, i have discovered this weekend that mine have packed up, i have done the usual checks (connector and fuse) and replaced relays but no luck, i was going to chase the wiring through next........
any help would be appreciated

Cheers
Chris
Did you try the relay just behind the rad/headstock tied onto the RH frame tube?
 

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To check if your fans are working, hit the kill switch but leave the ignition on.

You will hear the fans without the engine noise.

If they are not working, it would be advisable not to ride too much without them assisting cooling.

BTW hit the kill switch twice, the second one turns the kill switch off.
 

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It sounds as though your fans are not running. Before I get into this let me say that I know nothing about F4 Evo's. I have a Tambo which I am fairly new with but I know it's cooling fan circutry. I am going to assume that, if you have an ECU, the cooling fan circut is similar as MFG's tend to use the same components in certain systems. If not then disregard this whole post.

On the Tambo the fan circut is comprised of the fans, the relay to activate them, the temp sensor, the ECU and the wiring to connect them all together.
Any of these parts can be defective, although I doubt it's your wiring as the fuse isn't blowing.

The temp sensor for the fan circut is located on the engine. Where it is on yours I don't know but it should be easy enough to find. It sends a signal to the ECU and at a predetermined point the ECU activates the relay turning the fans on. It also serves the purpose, along with some other sensor input, of causing the ECU to retard the ignition timing, as the engine gets hot to prevent detonation. A rather important piece.

The relay recieves a signal from the ECU through two small wires which closes it and sends power to the fans through larger wires.

The only way you can test the sensor is to remove it and follow the instructions in the book. You can not "jump" it. Won't work as it's not an "on off" switch but rather varies current to the ECU in millivolts as the temp varies.

The relay can be tested by simply applying +12v to the positive tab for the small wire and grounding the negative. You have to use jumper wires from a 12v battery to bypass the ECU. If it "clicks" it's working. If not then replace it.

You can test the fan side of the relay by doing the same thing on the large wire terminals of the relay. Fans run it's good, they don't it's bad. Replace it.

I would begin by checking all the connections on everything in the circut.
If they are found to be good then I would replace both the temp sensor and the relay. They can't be that expensive and you will have eliminated them both as a source of trouble. You also have the benefit of having a new, accurate sensor.


That leaves the ECU. On my Tambo there is a small white with black stripe wire running from the relay to post #20 on the ECU. I believe it to be the negative wire, not the positive. If you have the sand you can disconnect the harness from the ECU and ground that wire. (Yours may be different but you can trace it down). Doing that will bypass the ECU and the temp sensor. If the fans then run then either the ECU or the temp sensor is bad. Do NOT megger with the ECU. With the harness disconnected you won't hurt it.

As I said in the beginning this only applies to the Tambo and assuming they're the same, F4's as well. It may be of no help with your F4 EVO but it's worth looking at.
 
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