Electric Radiator Fan Question

[400bird]

What's the actual temp the fan comes on at?
What temperature does the thermostat open?

I had customer that was upset his fan came on at 210, which is a perfectly reasonable temperature for it to cycle on at. The car had a 195 thermostat.

 

[EricB]

Does your intake have this port available?


Eric

 

[Jake M]

Most fan switches ive seen are in the radiator. Does yours have a provision to mount it there?

Those are the DIY universal kits. That does "work", but it's a long way off from a good solution. They actually work "OKish" for a daily driver if you're not in city traffic. But to prevent the engine temperature from "spiking" in traffic, they have to be set to come on early and turn off late. The fan just runs too much. Less of a problem with a "small" fan, more of an annoyance with a stronger fan, but in the end, they do work...

 

[slow-poke]

I actually have my sensor in the cooling fins of the radiator. It works well. Early Mustangs (65-66) have a tiny radiator, many years ago I had a rad shop upgrade it, IIRC they used either a 3 or 4 core from a Chevy pickup. So still a small surface area but thicker. No problem cooling the 408c.i.

 

[pdentrem]

You can get switches that have different set points. The previous owner had a 225 and I did not like that! The fan was also only a 5 blade, so I switched out the fan to a 9 blade that moves double the air and the switch now 180. The dash meter and the fan switch are both mounted in the intake manifold near the thermostat on the crossover. Before the temps were always 220 or higher, now the temps are closer to 200 and the fan cycles off and on while before it never did. I am much more relaxed in heavy slow traffic now!

I thought about the adjustable switch but I decided due to experience at the dealership that a simple switch is better and oem version are most reliable. I would place the switch before the thermostat as mentioned earlier. What happens if the stat sticks closed? No idea until too late.
Pierre

 

[682bear]

What's the actual temp the fan comes on at?
What temperature does the thermostat open?

I had customer that was upset his fan came on at 210, which is a perfectly reasonable temperature for it to cycle on at. The car had a 195 thermostat.

I think it comes on at 225 or a little higher. The thermostat opens quite a bit lower than that.

Does your intake have this port available?
View attachment 573251

Eric

Yes... that is where the guage sender is mounted.

-Bear

 

[EricB]

Yes... that is where the guage sender is mounted.

-Bear

I think that would be a better choice than the way you have it in the water hose elbow. You want water flowing around the sensor. The fan does nothing until the thermostat is open anyway, so finding a thermostat housing with a port for the switch may be your best choice.

All the old fords (289/302) I've owned had mechnical fans and I could work on them. I miss them. I had a 66 Galaxie 500 with a 289 and FMX transmission. A real land yacht.

Eric

 

[NO704]

As an aside, i had a 500ci. Caddy that would always run warm. Added some water wetter to it, dropped temps about 15 degrees.

 

[jonano]

From what I remember (which means fact check this....), by the time these got feedback carburetors and/or EFI, Ford put the gauge sender on the intake, just to the left (driver's side) of the distributor, and the ECU sender was also in the intake, to the right (passenger side) and behind the distributor. They both required that the heater core to always have open flow, or the vacuum valve that bypassed the heater core, so the heater hoses (and the intake passages) always had some flow.

Those two senders, on any ford of that era (or most brands from that era), they never did read "the same", but they kept the engines working just fine.

Putting a temp sensor in the water neck (post thermostat) is hit and miss. It kinda depends on how much "leaking" is designed into the thermostat. Some makes/models did that from the factory, and it's fine. Others did not. If you've got a little leakage designed in (which is normal if it's designed in), then that's a great place to stick a sensor. If you've got a hard seal, barely leaks a drop, you end up with a "dead gauge" until you hit the cracking temperature, and the gauge "spikes" in an unsettling way.
You're looking at a fan switch (not a sensor...), which should be set well above the cracking temperature. You would more than likely have no issues at all with that little quirk. I suspect the water neck would be just fine.

Putting a "T" in a temp sensor is a gamble on a good day. Pressure measures fine that way, flow and temperature, not so much. Poor flow characteristics and a separation from the "mass" of the engine has every "potential" to make wierdness. Just like radiators need proper coolant flow to transfer heat effectively, your temp sensor needs direct contact with active coolant to read accurately. Unsteady readings, overreacting with/without fan activation, and so forth. The hard part of that is that sometimes they work fine... You've really got to "science" a setup like that to make sure it's right, even if it 'seems" right. I'd avoid that.

Honestly, placing a sensor is such a simple thing, but it's something that actually gets a LOT of attention when engines are built. Being a custom installation, you may have to try a couple of options.

Yes, your thinking is correct and the heater hose T-fitting is indeed too slow and inconsistent for accurate temperature sensing, which is why the fan is coming on late. The best location is where hot coolant leaves the engine after the thermostat opens, typically at the water neck or thermostat housing, or alternatively in an inline adapter on the upper radiator hose. Moving the sensor there will make the fan respond earlier and more accurately, so your idea of changing the mounting location is the right fix.