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850 electric fan in 240

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  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    @PaulG I'll give you my findings when it's installed, but I've heard it sounds quite different, the clutch fan being part of the signature sound of a redblock.
  • It gets rid of the taxi-ing Cessna noise, and allows you to hear the squeaking drive belts much more clearly.
  • At freeway speeds the fans windmill and generate power, so if you have your indicator LED wired to the same pole of a SPST relay as the fan motor, the LED will light as a result of that current flowing.

    To avoid this, I used a DPST relay with the motor wired to one pole, and the light (I was using a bulb) to the other, this way they were electrically separated when the relay was open. Using a bulb, I could watch it begin to glow faintly at about 70km/h, and get pretty bright at freeway speeds!

    I've never seen any of my electric fans come on above 40km/h, even in very high ambient temps.

    Upper or lower hose sensing methods both work well, as long as the switches are suited to the location. The setup on my 760 uses a sensor in the head and an adjustable controller, and holds the gauge needle rock solid under all conditions, and doesn't cause the fan to run for very long or too frequently at idle.

    Note that virtually all OEM applications use sensors in the head or thermostat housing.


    you can hear the fans running, as opposed to moving under pressure. My led is run by the trigger for the pull fan. You can see it light some days and others not, take this morning drive to work for instance, it never come on at any part of the drive unless stationary at the lights.

    As when I have my 1200mm high pressure fan running in the garage. (I use it for static tuning of the cars, bikes and removal of exhaust gasses from the garage) the fans will spin and led is inactive.

    also if im not mistaken, the factory gauges use a "compensation" circuit/board to reduce how much the gauge actually moves.

    my needle doesnt move until the car has already boiled, and your stuffed.
    Great info in this thread. Is there much less noise with the e-fan? Lose that noticeable 240 fan humming

    its tonnes quieter. especially in the warmer months when the fan is more often engaged.

    i like the set up better. and well im restricted to only using this set up. as mentioned earlier due to my intercooler depth
  • The gauge clusters have a circuit to "dampen" the movement of the temp and fuel gauge needles, so they don't move suddenly and erratically. They still respond to changes pretty quickly though, think of it like little shock absorbers for your gauge needles.
  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    You can bypass the damper circuit also, if you like.
  • Yeah the temp gauge is not a good one.
    Fuel I undrstand, the fluid does move very erratically.

    Though I've watched my needle sit smack in the center, while I hear the coolant gurgling sound while all the pressure is pissing out of the reserve tank. shortly after that it jumps into the high section, then off the gauge.
    You can bypass the damper circuit also, if you like.

    yeah ive read the threads on that, im bypassing the gauge completely and replacing it with a digital gauge.

  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    edited February 2016
    Okay I installed the system today and ran some tests.

    1. 88 on is too high, the temp gauge gets about 80% of the way to the red zone before the fan comes on. I think an 82 on would be better. 79 off isn't too bad, but you can't really get standard sensors with an 82 on 79 off, the closest will be 82 on 74 off (180F-165F)
    2. Half-speed works but not fast enough
    3. Full-speed works and is fast enough
    4. The hotly contested upper vs lower rad hose debate: I worst-cased the cooling. I waited until it was hot but the fan hadn't yet switched on, then I launched the shit out of the 240 and red-lined it as long as I could. Fan kicked in, temp gauge stopped in its tracks almost immediately. This was with a fully heat-soaked engine bay after 20 minutes of driving around.
    5. Sitting idle it isn't too bad, you can hardly hear the fan. It comes on for about 30 seconds every two minutes or so.
  • Well I've now got the adapter to go in the hose but I'm wondering what sender unit I should get for my B234 engine. Maybe one for a 940?
  • I've had my E-Fan setup since 2009 and while it works great ill be going back to the clutch fan when i rebuild my 240. I only went with the E-Fan because of the reduction in noise and because it gave me more room for the intercooler, but now im running an ebay intercooler in the front so the space is reclaimed. The E-Fan does work well but a clutch fan keeps things far cooler with less effort and obviously no wiring.

    I will probably re-purpose my e-fan as a pusher fan for the AC/Intercooler for when heatsoak is a problem in traffic.
  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    @Slowbrick what thermostat on/off temps have you been using?
  • If I can remember I run an 82' thermostat and an 82' switch in the lower hose. Reason for this is that it opens the water to the rad at 82' and if the rad is working like it should the water returning should be considerably cooler than 82'. The gauge sits right in the middle and doesnt really move. I only have it on the low speed and find that its plenty.

    I do have a 100' in the top of the rad in the bung that is normally a blockoff in 240's. I found this is good for really hot days or spirited driving when the low speed doesnt quite cut it. It also helps prevent the massive surge of having the fan going from zero to fullspeed in one go as the low speed cuts in first and the fan steps up to the high speed.

    Its all been working great but I'm moving towards a more simple approach and hence why im ditching it in the the next revision.
  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    edited February 2016
    I'm going to swap my thermostat for an 82 on 74 off and see how that goes.

    @Slowbrick I didn't think to swap in a lower-temp thermostat (OE is 87 right?) does that have any other side-effects?

    Edit: also, you use a Datsun coolant bottle right? Do you know what pressure your system runs at? Reading online looks like it makes a difference if you run the black or green coolant cap.
  • I think OE was between 87 and 92 depending on which thermostat you get. The Datsun bottle is just for the washers because it fit in the spot.

    Im running the black cap which is 75kpa. The green one iirc is 130kpa. The black cap will spit coolant on hotter days and the green cap wont. I ran the green cap and I found it trashed my heater core due to the higher pressures. Not much of problem on a 7 or 9 because they are easy to replace, but bit of a problem in a 2 where they arent so easy to replace. The green will keep the system cooler due to it holding pressure but the cost of replacing heaters and hoses wasnt worth the cost of just topping up the premix on hotter days.

    240 heater cores were never designed for the increased pressure and I run a black cap on both turbos I have. Each to their own but if you are running an old heater core and hoses expect to have to replace it soon after running a green cap.
  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    240 heater cores

    I'm gonna stick with the black cap then.

  • Anyone have a fan shroud from a 740 turbo that I can use for an electric fan setup?
    I've now got the fan, still need the shroud and temp sensor - any recommendations on what to use? My plan is to put it in the upper radiator hose as that seems to be a popular choice, happy to be told to do otherwise though.
    I probably can't use the relay that came with the fan, can I? If not, can I just use pretty much any 5 pin Bosch relay?
  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    @240 which fan did you get?
  • @240 which fan did you get?

    One from a 960, which I understand is the same as the 850 ones.
  • I'd use the relay and the wire connectors if you have them. If you have concerns about the relay you can buy new ones on eBay. I cut down the 960 shroud to fit my 740, but putting the fan in the std shroud works too and may look cleaner. Make sure you use heavy gauge wire for the fan as it draws a LOT of power. I'm using mine on the 50% setting. Haven't needed the 100% one.
  • jamesincJames (@jamesinc) Oz Volvo Ice Fortress
    I used the relays and wiring from the 850. Ended up being pretty neat.
  • @jamesinc what configuration did you use the 850 relay in? Wiring diagrams I've found call for a relay with pins 85, 86, 87 and 30, but the 850 relay only has 2, 1, 2, 1, 30...

    If anyone has recommendations on a suitable thermoswitch that'd be great.
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