355 Proper Cooling Fans operation | FerrariChat

355 Proper Cooling Fans operation

Discussion in '348/355' started by Carmellini, Jan 28, 2021.

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  1. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Reading a number of previous threads about cooling fan operation and there is a lot of contradiction. Perhaps the seasoned and more experienced will chime in and provide a comprehensive tutorial on proper function. . i would rather not repeat what I believe, since it is only from threads I have read and I don't know which one is accurate.

    On my Porsche, when one fan is not working, the slack is taken up by the other fan which defaults to its highest speed? I don't think that is how the 355 system works? Are the fans one speed only or variable?

    My LH fan was not working and the remedy was to replace the blown 15A fuse with the correct 30A. My RH fan seems to be on more often and cycles less?? LH fan cycles more frequently: on 10 seconds, off 20 seconds and repeats.

    In addition, the LH fan starts to cycle at 200'? I think that is too high? Thinking it might be the thermoswitch on the top of the LH radiator?
     
  2. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    I'd like to know this information as well (as a new 355 owner). Have also done a lot of archives reading but still not sure how the fans are supposed to operate -- which one switches on at what temp, etc.
     
  3. taz355

    taz355 F1 Veteran
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    Feb 18, 2008
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    Grant
    I can only comment on my 99
    Left hand fan comes on on every drive around 200 and cools to about 190
    It cycles regularly
    The right hand fan has only come on when driving extremely hard and temps get to about 210
     
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  4. taz355

    taz355 F1 Veteran
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    Feb 18, 2008
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    My workshop manual explains it this way as well
     
  5. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    WSM says LH fan should come on at 190' and switches off when temp drops below 179' . ^^^perhaps your is not working properly?


    [​IMG]
     
  6. Roth

    Roth Formula Junior

    Apr 1, 2016
    433
    Pepsi Generation
    The fans are not variable speed and operate independently corresponding to temperate set points. The driver side fan comes on first once a minimum temperature set point is met. The passenger side fan comes on when the second temperature set point is reached. The second fan seldom come on while driving or driving in "grandma mode" unless ambient temperature in your area is in the 90's.
     
  7. Targatime

    Targatime Formula 3

    Feb 22, 2014
    1,211
    Los Angeles
    Interesting. The other day I was driving in grandma mode (one could even call it frail, elderly grandma mode) and pulled over to check, and both fans were on. I have very little seat time in my car but so far water temps haven't gotten above 190.
     
  8. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    Reading further in the WSM states the RH cooling fan gets its signal via the NTC water temp sensor, which sends a signal to the ECU when coolant temp hits 95C/203F, and then the ECU sends a signal to the RH cooling fan.
     
  9. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    I would guess your system is working fine, Grandma. (lol) Even though your dash gauge is reading 190, it is possible that the NTC sensor is reading a bit higher and thus your RH fan is on?
     
  10. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    I would like to replace the engine temp sensors and the thermoswitch on the LH radiator. does anyone know the Bosch numbers? According to the sticky, here is the one for the NTC temp sensor next to the oil filter (is this correct?)

    NTC sensor Ferrari 125769 Bosch 0280130026
    Temp sensor Ferrari 148677 Bosch ?????
    Rad switch Ferrari 158655 Bosch ?????
     
  11. Qavion

    Qavion F1 World Champ
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    Feb 20, 2015
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    #11 Qavion, Jan 28, 2021
    Last edited: Jan 28, 2021
  12. yelcab

    yelcab F1 World Champ
    Consultant

    Nov 29, 2001
    12,661
    San Carlos, CA
    Full Name:
    Mitchell Le
    Ian, do you drive your car? That is too clean.
     
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  13. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    +355
     
  14. Qavion

    Qavion F1 World Champ
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    Ooops... I should have mentioned I "borrowed" the photo from a fellow F-Chatter (Also, I also have a 5.2, not a 2.7). I don't often look under the coolant tank, so I'm not sure if mine is as clean (but I only did 50 miles last year... so maybe).
     
  15. m.stojanovic

    m.stojanovic F1 Rookie
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    Dec 22, 2011
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    The TS2648 (comes as Valeo, Vernet or Calorstat, all seem same) has good temp range, 87-82 C, and the connector appears to be the same as Ferrari's original (I have one for spare but I have not tried to actually plug it in). This company (Estonia) has probably the lowest prices you can find.

    Image Unavailable, Please Login https://spareto.com/products/calorstat-by-vernet-temperature-switch-radiator-fan/ts2648


    Same connector as TS2648 but by Wahler:
    Image Unavailable, Please Login https://spareto.com/products/wahler-temperature-switch-radiator-fan/6031-88d


    This is an interesting alternative - easy to find the connector as it is the standard Bosch 3-pin and the switch is dual so you have a choice of switching temperatures:
    Image Unavailable, Please Login https://spareto.com/products/calorstat-by-vernet-temperature-switch-radiator-fan/ts1769


    Large choice for Ferrari 125769 (incl. Bosch 0280130026): https://spareto.com/products?utf8=%E2%9C%93&keywords=125769

    They don't seem to have 148677 nor the original rad switch 158655.
     
  16. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    A bit confused about the 158655 radiator switch: According to the WSM this switch should operate within 82/87. The correct original Ferrari in the yellow box 158655 switch is 87/92??

    Is it better to get an aftermarket switch that corresponds to the WSM? Not a huge temp difference between the two, but I am torn between the idea of having a warmer running engine and the fact that I live in a very hot and humid climate?
     
  17. Qavion

    Qavion F1 World Champ
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    Where did you see the yellow box?

    The Maranello Classic Parts website shows a photo of an original (88/82C) P/N 158655 (supercedes 140314) and an alternative listing with (92/87C) quoted, but the accompanying photo for the alternative shows 88/82C :rolleyes:

    https://www.ferrariparts.co.uk/part/ferrari/158655?id=28411

    A photo of 140314 (original) on one website shows 87/82C (one degree lower for closing), but it's marked 171331 (no hits on Google for this number).

    https://www.autoepoca.it/portfolio/ferrari-512-mondial-348-temperature-switch-140314/

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    In the F355/355F1 Parts Thread....

    https://www.ferrarichat.com/forum/posts/145274280/

    ... it shows an alternative manufacturer with a temp value of 87-82C, according to Robbe
     
  18. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    ^^^^interesting......is it odd that Ferrari would specify an 82' thermostat and a "matching" 82' value on the fan switch?
    I would assume that you would want a fan switch to be a little high temp value? otherwise the fan is competing with the thermostat?

    FWIW: I asked Ricambi to look at 158655 and was told a visual check of the sensor was 92/87.

    Seems that I have two options: According to the WSM, 92/87 is NOT correct??? Not comprehending??
     
  19. m.stojanovic

    m.stojanovic F1 Rookie
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    For such climate, probably better to go with 82/87. Also, switching "on" at 87C means the temperature of the coolant exiting the radiator (after it has been cooled down) and not the engine temperature. At that point, the engine temperature will be higher, ~92C I guess.
     
  20. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    OK...thanks for that.....one more for the rear view mirror. Will get the 82/87.

    today I paid very close attention to the operation of both fans: My LH fan comes on about 198F and only stays on for about 10 seconds at a time, and then cycles off. Can we agree that this strongly suggests a faulty fan temp switch?

    I will call my RH fan the "dominant" fan? WSM says it should come on at 203F, but mine comes on about 196F, before the LH fan, and stays on until I drive and forced air shuts it off. Can I assume that my NTC sensor is bad as well? It is turning on the fan too soon....or maybe the NTC is "thinking" the water temp is at 203F?
     
  21. Qavion

    Qavion F1 World Champ
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    Using what reference? OBD2 readout or instrument gauge? I can't see how you can establish which reference is correct. You said in PM your gauge differed from the OBD2 readout, but the sensors are only a few inches away from each other. The LH radiator temperature switch is further away, however.

    I would at least pull the switch out and put the sensing end in pot of hot water on the stove and heat it up slowly and measure with an ohmmeter when the switch closes and measure the water temperature with a digital thermometer ($10 on eBay). Even if you buy new thermostats, it's a good idea to check them before installing them.

    I can't see the logic in this, Miro. The engine is designed to operate at a specific temperatures well above ambient temperatures.
     
  22. Carmellini

    Carmellini Formula Junior

    Jul 16, 2019
    814
    My OBD scanner, which I assume is correct......however, it must be getting the values from the ECU via the NTC?
    That's why I ask if my NTC might also be faulty? Thinking there is little doubt about the radiator fan switch?
     
  23. m.stojanovic

    m.stojanovic F1 Rookie
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    Dec 22, 2011
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    198F (92C) engine temp seems about right for an 87/82 thermo-switch. How long it stays "on" depends on how rapidly the water is cooled in the radiator. In lower ambient temperatures, the "on" time will be shorter. But a somewhat faulty thermo-switch could also cause too short or too long "on" times. I test these switches by immersing them in water in a saucepan (upright to keep the connector pins dry), connect a multimeter to it switched to "beep" function for continuity, immerse a thermometer, slowly heat the water on the stove and record the "on" temp. Then I let it cool down and wait for the "off" temperature.

    You can also test the NTC sensor in the same way but by having the multimeter at Kohm range, take the readings, say, every 5 or 10 C and compare them with this table of values for Bosch 0 280 130 026:

    Image Unavailable, Please Login

    I have also attached the Bosch document (pdf) on this sensor.
     

    Attached Files:

  24. m.stojanovic

    m.stojanovic F1 Rookie
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    The primary control of the engine running temp is the thermostat. The rad fan switch is actually helping the thermostat when it is unable to hold the engine temp any longer, like when the car is stationary. So, the question here is when do you prefer the fan to start this "help". At 87C water after rad (~92C engine temp) or at 92C water after rad (~97C engine temp). In hotter climates, it is probably better to get the "help" a bit earlier and it will also keep the engine compartment temps somewhat lower when stationary. Otherwise, it doesn't really make a huge difference between 92 and 87 C rad fan switches.
     
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  25. Qavion

    Qavion F1 World Champ
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    Correct (assuming the electronics are ok).

    I think we've reached a point where the only way to move forward is to start testing the sensors off the car as per Miro's instructions. These temperature sensors, thermostats, switches and transmitters are at different point in the system (and possibly all at different temperatures due to their locations).

    If the thermostat is designed to open at 176~178C (80 to 85C) we can assume that, ideally, the coolant is to get no hotter than this after leaving (?) the engine. But where are the other devices in relation to this?

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