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the cooling fan...

Discussion in 'Yamaha 250cc In-Line 4's' started by METOO, Feb 5, 2010.

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  1. METOO

    METOO New Member

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    you wouldnt believe it but i tested the thermoswitch and.... it works <!-- s:shock: --><img src="{SMILIES_PATH}/icon_eek.gif" alt=":shock:" title="Shocked" /><!-- s:shock: -->

    the only thing i can think of now is that maybe my thermostat isnt opening, so the hot water isn't getting to the switch, turning it on.

    the only other plausible thing in my mind is maybe the waterpump isnt working so the water isnt circulating.

    any of these seem possible to anyone? what temp does the gauge show on everyone elses fizzer before the fan kicks in? maybe mine is off or something..
     
    METOO, Apr 10, 2010
    #21
  2. METOO

    METOO New Member

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    ok this is starting to get frustrating....

    the water pump looks completely fine, no sign of wear and it only has about 3mm of free play when trying to turn it.

    i cant check the thermostat properly as the two alan key screws are in so damn tight i cant undo them (seriously) but i put boiling hot water into the top and it came out the bottom, but it also did that for cold water. So even if thats not working perfectly, water is still getting through..

    so now im open to any suggestions as to why my fan wont turn on automatically when its not the wiring and not the water circulation problems...
     
    METOO, Apr 11, 2010
    #22
  3. dave

    dave Well-Known Member

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    The other thing is maybe the temperature gauge is reading higher than it should?? Both the gauge sensor and switch are in the same housing.

    It does not sound like a coolant flow problem as it cools down as soon as you get airflow thru the radiator.
     
    dave, Apr 11, 2010
    #23
  4. METOO

    METOO New Member

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    yeah i thought it could be that but it all seems about right, and when it goes into the red zone the engine is gettin bloody hot and the water level rises really high.

    what temp on the gauge does the fan usually come on for most people?
     
    METOO, Apr 11, 2010
    #24
  5. rodeobob

    rodeobob New Member

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    It should have a small bypass hole in it.

    The water flows the other way.


    What you could do is remove the hose that exits the housing and goes to the radiator.
    Hold it upright and run a hose in it, you will need to adjust the flow.
    Start and run the motor and pay attention to the water coming out of the housing. While the engine is cold the water should just dribble out. When it gets up to temprature the water should come out in a rush.


    I think you might find that the thermostat is stuck open or there is no thermostat at all.


    If that is the case, the small amount of coolant that is in the system can just circulate of its own free will. It can build heat and build heat untill it boils. It does not get long enough in the radiator to effectively cool. And because the waterpump has nothing to push water pressure against it can also cavitate.
    If the thermostat is not closed chances are that the themo switch for the fan is not seeing a hot enough temprature for the fan to kick in.



    Cheers, Bob.
     
    rodeobob, May 25, 2010
    #25
  6. METOO

    METOO New Member

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    sorry guys there was no reply in this i forgot to say my findings..

    what i ended up doing was i took the housing to a mechanics and they got it open for me (cost nothing), there is a themoswitch and it works (put it in a pot and it opened as it got hotter).

    So i put it all back together, put in the thermoswitch that was working, changed the coolant and ran some radiator flush through it and put on the manual switch.

    I THINK its working now but i don't really want to run it that hot again to check, seems fine and no overheating problems as yet. To be honest, pretty over screwing around with the cooling system and besides, thanks to these problems i watch the temp gauge like a hawk so if it does get really hot and the fan still doesn't come on ill just flick the switch, oh and i haven't had to add any coolant since i put in the new stuff a month or two ago.

    Thanks all
     
    METOO, May 26, 2010
    #26
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