Pre 99 Peterbilts running hot cools down after manualy turning fan on.

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Mad dog logistics llc, May 18, 2022.

  1. Mad dog logistics llc

    Mad dog logistics llc Light Load Member

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    I have 2 peterbilts (N-14)new ECM & (5EK) both will run up past 205 N14 says check fluids driver will turn fan on and temp goes down. 5EK will say shut down driver will turn fan on and temp goes down. If both do this seems like a peterbilt issue not a ECM or Engine issue. Has anyone else had this problem seems like the fans are not coming on when told to come on. This is all Illinois driving no on 55 hills no west coast heat. Fluids full.
     
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  3. Goodysnap

    Goodysnap Road Train Member

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    205 is not hot. Either the warnings are coming on for other reasons. Or it’s hotter that the gauge is showing.

    Fan won’t come on til 217. And certainly shouldn’t have any overheat warning until your over that.
     
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  4. kranky1

    kranky1 Road Train Member

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    Not sure about the N14, but the 5EK thermostat shouldn’t even be all the way open until 190, and the ECM trips the fan at 217-218. I’ve got 2 5EK’s in KW’s and the gauges in both of them read 205-210 when the fan comes on. Out 10deg +/- from what the ECM is seeing. I’ve got a BXS behaves the same way.
     
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  5. J.R.

    J.R. Bobtail Member

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    My 00 N-14 comes on at 205.

    Check spare fuses 3 & 7 if it comes on manual, but not auto.
     
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  6. spsauerland

    spsauerland Road Train Member

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    Original flash file on 5EK would be 205 fan on, different flash file could be 217. High water temp light is from separate switch in thermostat housing and temp gauge another sending unit. Cat ECM controls 12V on fan clutch solenoid in 99 for sure, being 5EK yours is older. Cummins controls a relay. Last six of VIN and I will get diagrams.
     
    Last edited: May 18, 2022
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