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Transmission Causing Loud Fan?

Thread in 'Drivetrain: 4x2' started by Tyler Brown, Sep 29, 2017.

  1. Tyler Brown

    Tyler Brown Member

    Likes Received:
    Nov 11, 2015
    Hot Springs, AR
    Hey guys. I'm at a loss for what may be wrong with my 2005 Sport Trac. When I start the truck, the radiator fan just starts wailing for a few seconds. After about a minute, it will calm down, then go back to normal. It will remain normal for about 20 minutes, but as soon as the truck is warmed up, it starts going crazy again.

    It only makes this noise when I press the gas, and only makes this noise in 1st, 2nd, and 3rd gears. I have ruled out a bad fan clutch, as I replaced it and that didn't solve the issue. I heard that it may be an issue with a valve body solenoid telling the computer that the transmission is overheating. I replaced the entire valve body and every solenoid, but am still having the problem. Every time the fan kicks in this way, the truck loses all power. It has shot my gas mileage down to about 14-15, when it was previously 18+.

    An interesting thing to note is that if I pull the fuse that controls the transmission, the noise stops. The fan will work normally at start up, and when I press the gas, the fan won't freak out. However, as soon as I put the transmission fuse back in, all heck breaks loose.

    I've been told by a mechanic that this may mean that the transmission pump is going bad? But I don't understand why these symptoms would indicate a bad pump.

    Have any of you guys had a similar issue, or have any idea what may be causing this?
  2. EddieS'04

    EddieS'04 Well-Known Member 1st Gen Owner 2 Wheel Drive V6 Engine

    Likes Received:
    Sep 26, 2004
    Pasadena, TX
    For an 2005. This dont make sense. Your fan is thermo-mechanical, no trans or ECU ties. Unless you have an aftermarket electric fan tied to the ECU.

    The 2007 and up is Thermo electric. Is tied to the ECU...
  3. Taylor Corn

    Taylor Corn Active Member

    Likes Received:
    Nov 25, 2013
    Amarillo, TEX
    Mechanical fan on 05 isn't it? I know you said you changed the fan clutch but that is tell tale sign of fan clutch failure, unless you are overheating.

    Are revs going up with fan noise? Should be.
  4. Richard L

    Richard L Well-Known Member 1st Gen Owner

    Likes Received:
    Jan 8, 2001
    Waco, TX

    Like the others have said...there is no logical connection between the transmission and the fan speed.

    You might want to revisit the fan clutch and not simply rule it out because you recently replaced it. Also, you might want to check your coolant level and thermostat. That makes more sense than linking it to your transmission.

    Remember that the engine cooling fan is designed to operate when it detects hot air coming through the radiator which typically happens when you are stopped at a traffic light. When you get above 30-35 mph, the fan should sense the cooler air and disengage the clutch to let the fan free-wheel. If the fan noise stops when when you get into 3rd gear, it only means that you are going at a speed (30+ MPH) and enough cool air is going through the radiator that it does not require the fan to pull the air thru. The fan operation has nothing to do with the transmission !

    The fact that you are linking the transmission to the speed of the engine fan???...makes me wonder how much experience you have with automotive technology and gives me cause to suspect that you mis-diagnosed the problem and probably did not need the fan clutch that you replaced, since it did not solve the problem?


    Last edited by a moderator: Oct 5, 2017

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