Ford Twin Thermo Install ?

[Rob_C110GTR]

Hi

I'm wanting to install a ford twin thermo fans in my R32 with RB25

Stock fan was removed by previous owner , and I've got a twin thermo ready anyway so thought might just use that. And I've read the stock fan vs electric fans debate.

Anyone here done this swap ?

1. I would like to know how do you mount the twin thermo shroud to the radiator after trimming it?

2. How do you wire it up so that if the switch fails the thermos will run constant while the engine is running.

I've read that you can replace the bottom radiator hose switch with a tridon model and hook this up to switch the relay and then the fans on.

Anyone know which tridon switch? Is it the TFS141?

What happens to the wire connected to the old switch ? Or do I just reconnect that and splice a new wire to go to the relays.

Also the thermo fans are dual speed, how do I get that working properly with the wiring?

Thanks in advance and sorry if I've asked too many questions

[blind_elk]

2. How do you wire it up so that if the switch fails the thermos will run constant while the engine is running.

You DO NOT need the fans running while the engine is running. It simply defeats the purpose of thermo fans, namely to control a severe overtemp occurrence. Normal movement of the car keeps the engine to the thermostatted temp. The only time you need the fans is when the engine gets a bit hot during stop-start heavy traffic.

A secondary benefit is to free up a few kW by removing some load from the engine. Having the fans running all the time simply moves the load on the engine from the water pump to the alternator. I wish people would accept this wisdom from a 40year veteran of driving and playing with cars.

[Rob_C110GTR]

That's ONLY IF the switch fails as I mentioned

[jiffo]

Series/parallel relays will run your fans at two speeds.

I don't like using the bottom tank thermo switch to trigger fans, overtemp switch perhaps.

I prefer to mount the main thermo fan switch beside the ecu temp probe.

[kitto]

Revert back to mechanical fan with factory shroud. Done.

[blind_elk]

That's ONLY IF the switch fails as I mentioned

Just because the switch fails doesn't mean you need the fans on. So the engine gets a bit warm in heavy traffic, it won't kill it. Once the car gets moving again, temps will fall back to proper levels.

You DO NOT need the fans on permanently, EVER.

[Rob_C110GTR]

I've been looking at tridon dual switch

Which one would be best suited for the rb25

I can get one if those radiator adaptor that you fit between the hose but they all have only 1/8 npt thread. That can be fixed by tapping a new thread.

[mad082]

Just because the switch fails doesn't mean you need the fans on. So the engine gets a bit warm in heavy traffic, it won't kill it. Once the car gets moving again, temps will fall back to proper levels.

 

You DO NOT need the fans on permanently, EVER.

I would have to disagree to a certain extent. The stock fan is moving all the time, just moves faster when hot. If you use the aircon you want the fan moving all the time, regardless of speed or engine temp, plus if you have a fmic then you have reduced airflow through the radiator, etc.

Don't get me wrong, I've seen the thermofan operating specs for a different car and you are correct in a lot of what you say. When the aircon is off then they only operate if the temp is over a certain amount, and speed is under a certain amount (I have a screenshot of it on a computer somewhere). Having said that, it's been a while since I looked at it, but I sort of recall that they work at full speed at low vehicle speed and low speed at high vehicle speed (so not fully off). When the aircon is on then they operate at full speed, regardless of vehicle speed (only when the compressor idea engaged though I'm guessing). I may be wrong about some of that though. As I said it's been a long time since I looked at it.

But at the end of the day, being able to run the fans all the time as a failsafe isn't a bad idea. I'd prefer it to running the risk of boiling the engine in the event of a failure. Not to mention that it would act as a way to let you know that something has gone wrong.

[jiffo]

Plenty of room beside the factory sensors on a 25.

Would be simple to trigger the relay via an internal switch if you want to run the fans manually.

[SMOKEYV35]

I have used a Drift brand digital fan controller on BA thermos before with great results. Has some nifty features like set the temp the fans switch on, digital display of current temp, alarm warning for over temp (you set). Cost about 160 iirc. From autobarn.

[Rob_C110GTR]

Can the drift brand control low and high speed?

Don't really need a controller as the switch and relays can do that

[SMOKEYV35]

Not sure - you'd have to research - it was about 3 years and 5 cars ago lol.

I liked that it gave me a reference point in the cabin. I could see the temp and when the fans were on. Could also manually override if needed. I was too worried about something failing, the fans not coming on and me not noticing until too late.