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Thread: Thermo fan temp switch, what temps...?

  1. #1
    Join Date
    Nov 2011
    Location
    southern slopes
    Posts
    9

    Thermo fan temp switch, what temps...?

    G'day all,

    I just joined the forums however have been an interested reader for the past few months since I went all out and bought a 1985 carbie 'disposable' 4wd...!

    Anyhow, a couple of weeks ago I blew the bottom radiator hose (fortunately only about 1.5km from home) sat by the side of the road till she was cool, poured in an extra 5 litres of oil to provide some cooling ability and limped home.

    First thing monday morning I got on to the guys at Britcars in North Melbourne and in short order (these guys are brilliant!) had new top and bottom hoses, assorted gaskets etc. I eagerly waited for knock off and raced home to put the old girl back together, all went off without a hitch until during the refilling of the coolant system. Whilst running the engine to check for leaks I noticed a small leak at the neck of the filler nut, so out came the radiator and off down to the local bloke for a pressure test & repair..... (I bet you all think you can guess where this is heading!).
    I call back in on the way home only to find out that the radiator is in near perfect order, almost full cross flow and only the small hole to be soldered up!

    Anyhow now for the point of my post, the old girl was fitted with a set of thermo fans by the previous owner (a sparkie) who used an adjustable hot water thermo switch to kick the fans into gear, the type with a long thin tube & thicker bulb on the end, which was stuck into the upper hose where it attaches to the rad (jammed in between the upper tank inlet & the hose, held in by the hose clamp). During the removal of the to hose some boofhead with more strength than brains busted the bulb off the end of the tube (yes that boofhead would be me...).

    The long and the short of it I though I would take the opportunity to change over the temp switch to a 'temp switch hose adapter' style job such as this Coolant Fan Temperature Switch - GasSavers.org - Helping You Save at the Pump Hypermiling and Fuel Efficiency Forum (scroll down to tjts1) or as sold here 22mm Water Temperature Sensor Adaptor
    My main problem is I cant find anywhere what temperature the fans should cut in & cut out at?

    Cheers

  2. #2
    Join Date
    Jan 1970
    Location
    South Yundreup,WA. Bludging
    Posts
    7,051
    Usually you would set them to cut in at over 80deg c as this is normally about where thermostats open anyway. You can also link it to come on usually (1 of 2) when the air con is turned on. I personally dont like laying the bulb under the hose and went for an adaptor. Basically you cut the hose and place it in there. If you look at the Davies Craig website they are on there. The one you link to is for motor bikes etc. I got mine sent from Outlaw speed shop in Adelaide, I think around $26.
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  3. #3
    Join Date
    Aug 2006
    Location
    Melbourn(ish)
    Posts
    24,472
    depending on the engine... and im guessing by 85 carbies its a v8 Cut them in at about 90 degrees and out again at 80
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    TDI D1(its responded well to its lecture about poor performance)

    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

  4. #4
    What temps would you want it to cut in and out for on a 186 red motor running no aircon and a single thermo fan in front of the radiator? On a LWB series 3 if that makes any difference to engine load vs temp? I have the same setup as the O/P and I'm not happy with it, I want to convert to a proper thermal switch to do away with the tube and bulb device.

  5. #5
    Join Date
    May 2008
    Location
    Adelaide
    Posts
    372
    I use one of these to control the twin EL fans (as used on scores of V8 muscle cars in the US).

    Delta Current Controller Home

    The DCController uses a temperature sensor inserted between the fins in the radiator near the radiator outlet. The controller controls the fan speed by use of PWM (pulse width modulation) which is an efficient method of slowly ramping the fan speed up and down, which avoids large current surges that a simple relay control allows. Pulse Width Modulation allows the fan to be ramped up in speed so the fan only spins as fast as is necessary to cool then rad/engine. Instead of being turned on full speed. Also allows you to configure/tune the temp that the controller comes on at. Factory setting is 180F. No need for relays, easy to wire up

  6. #6
    Join Date
    Aug 2006
    Location
    Melbourn(ish)
    Posts
    24,472
    Quote Originally Posted by pfillery View Post
    What temps would you want it to cut in and out for on a 186 red motor running no aircon and a single thermo fan in front of the radiator? On a LWB series 3 if that makes any difference to engine load vs temp? I have the same setup as the O/P and I'm not happy with it, I want to convert to a proper thermal switch to do away with the tube and bulb device.

    pull the thermostat out.

    it''ll have a full open temp stamped on it.

    fans off 1 or 2 degrees above that, fans on 10 Degrees above that.
    Dave

    "In a Landrover the other vehicle is your crumple zone."

    For spelling call Rogets, for mechanicing call me.

    Fozzy, 2.25D SIII Ex DCA Ute
    TDI D1(its responded well to its lecture about poor performance)

    If you've benefited from one or more of my posts please remember, your taxes paid for my skill sets, I'm just trying to make sure you get your monies worth.
    If you think you're in front on the deal, pay it forwards.

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