98 pete fan clutch issues

Discussion in 'Peterbilt Forum' started by flaco, Mar 1, 2015.

  1. flaco

    flaco Bobtail Member

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    Mar 1, 2015
    laredo, texas
    0
    I have a 98 pete with a 3406e cat.
    Fan clutch stays on all the time from the time the truck builds up enough air for it to run.
    I checked the manual switch on the dashboard and disconnected the wires. Both wires have constant power as long as the ignition is "on"
    Checked switch on firewall, also recieving constant power.
    Anyone else run into this issue? Killing me on fuel not to mention that the truck wont reach its normal temperature.
     
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  3. 315wheelbase

    315wheelbase Heavy Load Member

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    check for air leaks in air hose running to fan clutch,
     
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  4. jbourque

    jbourque Heavy Load Member

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    south english iowa
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    air leak would be my guess also ,i would start looking around the fan clutch lots of luck
     
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  5. windsmith

    windsmith Road Train Member

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    I had a 98 Pete with a Detroit that had a similar issue. Turned out to be a chafed fuel temp sensor wire in the engine harness that shorted to the block. ECU activated the engine fan because it sensed high fuel temp.
     
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  6. flaco

    flaco Bobtail Member

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    Mar 1, 2015
    laredo, texas
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    Thanks guys, no air leaks so gonna check wiring now.
     
  7. bad-luck

    bad-luck Road Train Member

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    Air keeps the fan disengaged. So you have qn air leak, bad fan cylonid or a seized fan clutch
     
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  8. flaco

    flaco Bobtail Member

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    Mar 1, 2015
    laredo, texas
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    Okay bad-luck. Gonna check the solenoid. Fan turns freely when truck is off. Bypassed the hose with another one just to check...no leaks.
    But there is continous power to the solenoid as long as the ignition is on. Dont know if thats normal?
     
  9. windsmith

    windsmith Road Train Member

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    If the fan stops with the solenoid power disconnected, then you know the air circuit is working properly.
     
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  10. flaco

    flaco Bobtail Member

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    Mar 1, 2015
    laredo, texas
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    Yup. Disconnected power to the solenoid and the fan stopped.
    However, the "engine fan" light on the dash stays on.
     
  11. windsmith

    windsmith Road Train Member

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    So either the fan override circuit is shorted, or a sensor input is telling the ECU to command the fan clutch to engage.
     
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