electric fan sensor/thermostat combo Question
 

Hey guys, I'm running a 180 degree thermostat on my 302. I am running an electric fan with a water temp sensor/switch in the intake that turns on the fan when the water temp reaches 185 degrees and cuts off at 170 degrees. Well I noticed today that when my engine warmed up to operating temp the fan came on as it should but it didn't turn off and I had it running for a while. The temp always stays at around 190 degrees on my mechanical thermostat gauge so the fan doesn't have a chance to turn off. I know there is a sensor/switch that I can get that turns the fan on at 200 degrees and shuts off at 185 degrees....But If my engine stays at 190 degrees, wouldn't I have the same result?(the fan not shutting off) What do you guys suggest?

It is because the sensor is in the intake. With the engine off the block and intake stay hot a lot longer because there is no water flow (the water pump is not turning with the engine off). To fix the problem move the sensor to the radiator or switch the power for the fan to keyed on.

Yeah. VW puts the fan temp sender at the bottom right in the radiator!

If I use electric fans on mine, that's where I'll put it.

Cheers,


Rick

The temperature coming out of the engine isn't a good indication of need for fan operation. If it's 20 below outside and the radiator is doing its job, the water going back to the engine would be plenty cool without any fan. If you have the sensor at the thermostat housing, then it needs to be set at least 20 degrees above the thermostat's opening temperature.

Rick, I agree the lower tank makes more sense. Typical 2-speed German fan switches (Bosch) are set for 85 (low speed) and 93 (high speed), deg. C., which is equivalent to 185 / 200 deg F., water temp going back to the engine. That sounds like what Reed has, but in the wrong location.

Hey Reed,
We messed around with our electric fan system for quite a long time.
It sounds like we have the same set up - Our sensor works best at the bottom of the radiator. Now our summer project is to move all the fan relay stuff out of the inner fender well into the engine compartment somewhere. I just need to find room. It's failed twice inside the fender area - it doesnt like to be wet.

We went with the 180 degree thermostat as well - I wasn't comfortable with the 195 degree 351W stock thermostat - it ran too hot here in Texas.

Good luck over there.

Ben in Austin
1950 F1 351W

There is a place on the radiator I think I can actually put the sensor, right now I have a drain mechanism there so I can just turn a little handle and drain the fluid...Should I just remove that and put the sensor there? When ever I go to drain the fluid I would have to remove it but thats not a big deal. My sensor comes on at 185 and turns off at 170 do you think this would be efficient even in that location?

IMHO, on at 200 and off at 185 makes a lot more sense than on at 185 and off at 170. Since you have a 180 thermostat, the fan would never cut off as long as the engine is running. The on at 185 and off at 170 would be better used with a 160 degree thermostat than a 180. I do not want my fan running hardly at all so I opted for an on at 200 and off at 185 with a 160 thermostat. I also wired in a toggle switch under the dash so that I can override the coolant switch and turn the fan on at any temperature or off at any temperature but I'm hoping I never have to touch it.... :)

I went and checked the sensor I have and it is a 1/2 npt and the hole in the radiator is 3/8 npt I think, so it won't even fit, so I can't even try the switch I have out in the radiator. I searched around and found this switch below. Would this switch solve my troubles if I bought it and installed it in my radiator?

Electric Fan Sensor, 3/8 NPT - Speedway Motors, America's Oldest Speed Shop

Edit: actually the sensor I have is like a 5/8 npt and the radiator hole size 3/8 I think

I think this is a better bet. How you mount the probe is unclear. I suspect Hayden has an instruction sheet somewhere. The adjustable feature is what makes this better IMO.

Hayden Electric Fan Controls 3653 - SummitRacing.com

Can't beat the price, either. Bosch switches for my car cost about $50.

would this work
 

Hey folks,


ok I know this may not work but I thought I'd ask.


C12-3083-10 - IN LINE OIL THERMOSTAT TEMPERATURE CONTROL SWITCH 180 DEGREE


this link is for a 180 degree oil temp switch for turning on a fan.


I wonder if it would work for antifreeze in the hose to the heater core?


I'm in process of trying to find a way to add an electric fan to my 51' and maintain my dual temp gauges and "other than going with a probe type" this was my only other idea.


any thoughts here? never done it, thought I'd ask.


Plan b is the probe, I just hate to poke a buncha holes in the radiator as I may have to use the push thru clips to hold the fan on anyways.
Not having much luck finding a mounting bracket that fits a 22 in wide radiator yet.....
looking for options and ideas..... :-X16

To answer your question, yes it would work but just buy this and save a ton of money.
Derale Performance Replacement Electric Fan Thermostats 16728 - Free Shipping on Orders Over $99 at Summit Racing

Or you can go with this, this is what i have on my truck and it is adjustable.
Derale Performance Deluxe Adjustable Controllers with Pipe Threaded Probes 16749 - Free Shipping on Orders Over $99 at Summit Racing

My radiator did not have a bung in it where I could mount my temp sensor so I opted to go with an inline sleeve...works like a champ.

Hey Double,
We've got a '50 F1 with a 351W in it & we wanted to upgrade the cooling efficiency of our set up as we live in Texas.

They sell thermostat housings with an extra bung that you can use to screw in a temp. sensor. We went with a BMW (2)
speed sensor - pretty much come standard on all later model BMW's. You can find them for under $20 at Rock Auto. We are
using the Volvo 2 speed Fan Relay to control the Fan. We used an 18 inch (2) speed OEM (salvage) fan from a V8 Thunderbird - it's
the Mark VIII fan that flows 4500 cfm at top speed.

Here is a good write up on the set up...
Wiring 2 speed fan with volvo relay. - SyTy/SGT - Forums

Good luck over there in Virginia.


Ben in Austin
1950 F1

ideas
 

Hey Guys,


Thanks for the suggestions!


I WISH I had a 351, just got a ol' 8BA flathead that's still hanging on.

CharlieLed: I wish I could use the radiator hose pipe, that would be perfect but the Flathead looks like the rad pipe hoses are smaller (i'm not 100%) I've not drained the coolant and pulled hoses just yet..


Truckeemtnfords: I've looked at a bunch of Derale products here lately, sounds like they are good products. Thanks for confirming!


Howdy to Ben in Texas!
I checked out that link on the Volvo 2speed fan relay, that was pretty cool, me and a bud were "supposed' to make a junk yard visit soon. I could try to peep out some Volvos on that trip.
I know yall get hot down there, worked a job there many years back setting up Circuit City stores in the 90's, it was 80degrees at 6am! got to Dip a toe in the Gulf in Galveston!


Thanks for the tips and suggestions. I believe yall gave me an idea..


T

Where did you get the bung to fit the BMW sensor?