The operation of the cooling fans | FerrariChat

The operation of the cooling fans

Discussion in '365 GT4 2+2/400/412' started by bjwhite, Aug 16, 2014.

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  1. bjwhite

    bjwhite F1 Rookie

    Mar 17, 2006
    4,683
    Seattle, WA
    Full Name:
    Brian White
    #1 bjwhite, Aug 16, 2014
    In further work on my 400i, I've noticed that the car warms up properly...and then stays at a good operating temperature--unless I'm going slowly or stopped in some traffic...then the temp climbs, but I don't know what is normal.

    So in testing, the front two lower fans kick on around 85 C. But, seemingly no matter what the temperature climbs to, the radiator read mounted "pull" fan never comes on.

    I assume it should...and if so, at what temperature? I suspect this is why the car stays at a good temp until really stopped in traffic. At driving speed, the temp stays at a solid 85-90C the entire time. In traffic, it usually will climb to 100 or so....but then once it starts heading north of that I pretty much freak out and start taking maneuvers to get into clear air--even if that means getting off onto side streets or pulling off for a sandwich or something.

    This became clear during my drive from Portland yesterday.....traffic leaving Portland north to Washington is ALWAYS absolutely terrible.

    So....any ideas or confirmations on the operation of that fan? Also, any comments on normal operating temperature ranges would be nice too.
     
  2. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,112
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #2 Steve Magnusson, Aug 16, 2014
    Last edited: Aug 16, 2014
    The scan of the fuse-relay panel in the 250/82 OM is very poor, but it looks like all three relays (H, I, and J) controlling the three water radiator fans are wired in parallel -- so all should 3 fans should come "on" together (also, the text in Section 3 just simply says [paraphrasing] "the thermoswitch in the radiator controls the water fans" -- so implies common operation together).

    Check relay J and fuse #7 (you can also try swapping them with relay H or I and fuses #5 or #6 to see if the trouble follows one of the players). There are also connection(s) on the fuse-relay panel that could be frazzled, but unable to be much more specific unless you can provide a better scan of the fuse-relay panel schematic -- of course, you can just unplug them all and visually look for any frazzling. If no trouble found with relay/fuse/connections, you've got to either measure the voltage at the center water fan motor connector (while still plugged in) when it should be operating, or just put +12V from somewhere else directly on the unplugged motor connector to see if it works, or not. Good Hunting!
     
  3. rustytractor

    rustytractor Formula 3

    Mar 25, 2012
    1,078
    London
    Full Name:
    Russell Schacter
    #3 rustytractor, Aug 16, 2014
    Also, check that the wiring to the fans hasn't been reversed and hot air isn't being pulled through the rad from the engine.

    I know it sounds really unlikely but I had the same problem with my 365 and someone suggested I check the fan rotation direction. I was really sceptical but checked and one was pulling and the other pushing due to a badly executed fan replacement at some point in the dim distant past. I had other problems as well but this was a contributory factor.

    It takes 2 mins and is well worth checking.
     
  4. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,603
    Romulus, NY (Finger Lakes)
    Full Name:
    Ken Battle
    #4 SouthJersey400i, Aug 17, 2014
    There is one difference between the two push fans and the one pull fan. The push fans come on with the AC no matter what the coolant temperature is. I had similar issues and 2 fans on a hot day in traffic and you can over heat; you need all three.

    Follow the power signal to the pull fan when engine comes up to temp to see if you have power; easier yet put 12 volts on the fan to be sure it is okay....it will be. If you get into the fuse/relay panel you will find that you are not getting power to the pull fan or maybe only a few volts. The fuse / relay panel can not handle all the power going thru it.

    I have a previous post where I re-wired all three fans to use the 'stock' control signals to just send a signal to three remote relays, one for each fan. The fuse panel can handle the control signals but not the fan power. I put a small fuse box behind the battery with three fuses, one for each fan. I ran direct power to the fans and mounted a relay adjacent to each fan. I used the former power signal to the fan to be the control signal only and I used 12 gauge wire from fuse box to each relay. It was a simple job of snipping the power to the fan and making it the signal to the relay and old wire to fan went to output of relay.

    No problems in 3 years since the mod; this is same basic mod you need to do for your fuel pumps when they start acting up.
    Ken
     

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