Aftermarket electric fan water temp switch??

[disrupt]

I bought a set of spal electric fans for my rb26. They came with a temperature switch but it is 1/2" not thread!

What did you use? Where did you mount it? I'm looking for something I can bolt on to trigger my fan relays.

Thanks

[Skym]

Could use something like this (can adjust temp when fans kick in) -

http://www.eliseparts.com/products/show/84/222/radiator-fan-controller/

But not sure if it fits inside stock top radiator hose.

Or this adjustable temperature switch with thermister -

https://secure.vividcluster.crox.net.au/jaycar2005/productView.asp?ID=KC5381&form=CAT2&SUBCATID=965#11

Could put thermistor on outside of top radiator hose and use with above device.

Thermistor -

http://en.wikipedia.org/wiki/Thermistor

Jaycar in Canada -

http://www.jaycar.com/splash.html

[GTR203]

I have used a oem switch that worked just fine , it is a 2 wire temp switch on the lower right part of the rad, I wired it up with my relay kit and my dual 12" fans kick on right when they are suppose to.

[disrupt]

Thanks for the response skym. Gtr203, That's the kind of simplicity I want. Problem is I don't have a oem rad and the car is actually a s13. the thread is 3/8" npt on the sensor I have. It is a single terminal switch that grounds above 185f and ungrounds at 165. Power to the relay coil, ground the relay coil to the switch, and going to add manual bypass toggle switch. Right now i am planning to have an aluminum bung welded to the thermostat housing assuming it won't hit the thermostat. Otherwise I might have the bug welded onto the bottom rad end tank.

[GTR203]

What they have as well is a temp switch that slides into the rad that i have used and worked well as well. Its a long probe that reads off the rad temp.

[NismoS-tune]

I wired the switch into my AC (thermo) fan so the ecu turns it out but I have a different ecu...

I have seen people buy a sensor adapter and cut it into the rad feed hose to trigger the sensor.

[Dragon Humper]

Go to Mopac, buy a rad hose fitting insert for a 1/2 NPT fitting and splice it into your lower rad hose. Wire it up, done.

The piece you need must be sized to you rad hose(ie: 1 1/4 inlet/outlet with a 1/2" NPT fitting).





Jon.

[Skym]

Better in top radiator hose. Factory has temp sensors for ECU, dash placed near top radiator hose for a good reason.

If thermostat doesn't open, bottom radiator hose gets cold and top radiator hose gets warm. It can get cold enough that it won't activate switch if placed in bottom radiator hose or bottom of radiator.

I noticed Subaru (at factory) run the temp sensor on block for radiator fans, with a module to control fans. That's the best way, but top radiator hose is close to that.

[Dragon Humper]

Better in top radiator hose. Factory has temp sensors for ECU, dash placed near top radiator hose for a good reason.

If thermostat doesn't open, bottom radiator hose gets cold and top radiator hose gets warm. It can get cold enough that it won't activate switch if placed in bottom radiator hose or bottom of radiator.

I noticed Subaru (at factory) run the temp sensor on block for radiator fans, with a module to control fans. That's the best way, but top radiator hose is close to that.

Ahhh yes but.....the lower hose is the feed for the water pump. If the hose is cold then the thermo is closed and there is no coolant moving through the rad, no need for the fans to come on. As soon as the coolant starts to move the hose will heat up. Once it heats up past the trigger point of th switch, the fan(s) come on. Once you are moving enough that the airflow through the rad is cooling the engine the temp in the hose will drop enough that the fans will shut off. You don't want them running anymore than they have to, its hard on the alternator/fans and costs you HP (though not nearly as much as the stock fan does).


Jon.

[Skym]

That's when coolant system is working perfectly and once engine is up to operating temp the thermostat is always a little bit open (open fully at around 90 degrees C with coolant temp), so coolant temps are kept at roughly 80-90 degrees (varies while driving), so fans will be turning on and off while driving (depending on what coolant temp you have set switch at).

But like what happened on my car, thermostat late opened (thermostat failure) and coolant temps went to 95 degrees+ in engine before thermostat opened (tested thermostat afterwards), but stock radiator fan was still cooling block itself. Fan that was connected to bottom of radiator never came on because coolant temps was too low in bottom of radiator.

I can see what you mean with electric fans not being on all the time, as they have a limited amount of hours before bearing in centre of them fails. But also I can see with temp sensor on block, that it will react quicker to sudden spikes in coolant temperature quicker and even if above thermostat failure happens, fans will still cool engine.

I gather Subaru took into account thermostat failure and where it would make fans react quicker to sudden spikes in coolant temp. Basically fans will be activated by higher temp coolant in block, so will be already sucking enough air through radiator to cool coolant when it gets dumped into radiator while thrashing car to prevent coolant temps spiking. They must have learnt this from years of rally / testing.

Also with stock fan it uses heat from radiator to expand spring on front of centre part / clutch and engage clutch more thus spin fan faster. So with cool air coming through radiator when car is moving (and a little bit of heat off radiator) and spring not expanding as much, fan is not always putting alot of load on engine itself. Also is probably not putting alot of load on engine when it's warming up, as no hot water (coolant + water) is flowing through radiator, etc.

Actually thinking about it more, thermister would be bad idea if air from radiator moves over radiator hose thus turning fans off. Lotus switch idea in top radiator hose seems to be better.

[Dragon Humper]

Another thing to remember is thermal shock. If the sensor is on the top end and running the fans with very little coolant going through the rad the coolant will get really cold. Then when the thermo opens a rush of really cool liquid will start to course through the block, that's not good in a bi-metal engine( alum. head/iron block).

The only reason the factory puts the coolant temp sensor near the thermo is to get the worst case engine temp reading for temp correction in the spark map. That way you won't have det. somewhere else in the engine that may be hotter than where the reading is being sampled from.



Jon.

[Skym]

I can picture cold coolant, water + hot block, head = crack. But I gather fans must be preset to certain speed, so as to not overcool radiator. Would like to hear the reason behind why the engineer designed it that way (I might be totally wrong).

The ECU temp sensor is on top radiator hose, close to engine. Stock ECU does pull the ignition timing at 110 degrees C.

From what I understand, the bottom radiator switch is for when aircon is on and coolant temps excedes 90 degrees C (when stock switch activates) on a very hot day. Coolant temps usually never reach that high under normal driving, so switch never activates and fan never runs.

Initially I thought that fan infront of radiator, aircon cores was connected to ECU, but no. On wiring diagram I have of engine bay wiring loom, it looks like it is. But I gather the wiring for it is bunched with other wiring and runs along radiator support for a little bit, then to a plug that plugs into plug for fan infront of radiator, aircon cores.

[Dragon Humper]

Cracking is a little extreem but I guarrantee a headgasket will get farted out much sooner.

My AC has never worked but wouldn't the fan come on automatically as soon as the compressor kicks in? Every AC equipped vehicle I have had was an electric fan setup and the secondary (primary if there was only one) fan always would fire up as soon as the AC was turned on. Even my new truck which has a super fancy duty cycle control from the ECU fires up the secondary fan to 100% right off the bat. The ECU controls the 2 fans against a complicated set of perameters that can control the speed of the fans from 30% to 100% based on temp and rate of change.....not just off or on. I have a programming suite for it already, it's only 6 months old......lol.



Jon.

[Skym]

That's a interesting, cool AC setup.

Fan infront of radiator doesn't switch on when AC is on. AC on a R32 Skyline is roughly a 22 year old design.