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Electric fan problems and a question about temp the sensor
My pickup came with a Flex-a-lite fan with a temp probe that's stuck through the rad, at the top, close to the inlet. Fan worked fine a while ago. Would come on only for a second then go off. Never had any overheating issues. Recently, I noticed it was getting a little warm and the fan didn't kick on. Tested a few more times and it's definitely not working as it should. I still have to dig into it but, the probe through the radiator just seems phony. I was also wondering about the placement of the sensor. I know we're instructed, by people that know a lot more about these things than I do, to place the sensor as close to the rad inlet as possible. I'm wondering why we don't place it at or after the outlet of the rad. Here's my thinking. Putting the sensor at the inlet negates any passive cooling the rad does. While driving on a cold day, engine temp could rise, open the thermostat and let fluid through the rad. At the inlet, the fluid will be hot, trip the sensor and turn on the fan before the fluid has a chance to flow through the rad. The fan may never need to be turned on if you're driving through cold air. Why not put the temp sensor at the outlet and if the amount of cooling from the natural flow of air is insufficient, then the fan would be turned on? It seems like you'd want to know what the rad is doing by itself before deciding if you want to get more air moving. Isn't the less you have to turn on the fan, the better?
TLDR: Probe is junk, flex-a-lite is junk, if radiator is HD LC modified 3-row that's junk too, almost everything LC makes is junk except their header. They sell some nice stuff made by others.
My experience with that probe was that it was garbage. The fins will eventually loosen up to where it does not read accurately and then you'll have to find another spot to put it. If you're super committed to keeping the fan I'd get the soft-start controller with the threaded temp sensor, have a bung welded into the radiator tank, and rig up an override switch so you can turn the fan on while driving. And if you have one bung welded in you may as well have another for an independent temp gauge because based on my experience you will wonder whether your temp gauge is broken when you still run warm with the flex-a-lite on full blast. https://smile.amazon.com/gp/product/B001UPYW1W/
But why not learn from my mistake of throwing a great deal of good money after bad with respect to the Flex-a-lite setup and go back to the stock fan and stock shroud, and if you have the "special" LC garbage radiator modified for the flex-a-lite throw that thing in the trash can too and get the right CSF radiator at the same time, probably either the 2314 or 2306, but I can't quite tell what year your rig is. Moving the brackets as LC does for that radiator (it starts out as just a CSF 2314) is a bad idea. If you do keep the fan let us know how it works out...seems like some people do OK with the Taurus fan conversion but I've never heard of a flex-a-lite working out on these rigs. As far as temp sensor location goes I see what you're saying but maybe depending on driving conditions for one temp at the radiator outlet temp at the radiator inlet can vary from OK to not OK. It seems like the ideal system might have sensors at both locations with some smart circuitry for controlling the fan.
My pickup came with a Flex-a-lite fan with a temp probe that's stuck through the rad, at the top, close to the inlet. Fan worked fine a while ago. Would come on only for a second then go off. Never had any overheating issues. Recently, I noticed it was getting a little warm and the fan didn't kick on. Tested a few more times and it's definitely not working as it should. I still have to dig into it but, the probe through the radiator just seems phony. I was also wondering about the placement of the sensor. I know we're instructed, by people that know a lot more about these things than I do, to place the sensor as close to the rad inlet as possible. I'm wondering why we don't place it at or after the outlet of the rad. Here's my thinking. Putting the sensor at the inlet negates any passive cooling the rad does. While driving on a cold day, engine temp could rise, open the thermostat and let fluid through the rad. At the inlet, the fluid will be hot, trip the sensor and turn on the fan before the fluid has a chance to flow through the rad. The fan may never need to be turned on if you're driving through cold air. Why not put the temp sensor at the outlet and if the amount of cooling from the natural flow of air is insufficient, then the fan would be turned on? It seems like you'd want to know what the rad is doing by itself before deciding if you want to get more air moving. Isn't the less you have to turn on the fan, the better?
If you are trying to limit (control) engine temperature you put the temperature element as close to the hottest part of the engine as you can.
If putting the temperature probe on the radiator outlet is a good idea why does every engine manufacturer put them on the top of the engine or at the thermostat outlet?
Aftermarket fan controls use a probe shoved into the radiator fins or upper radiator hose because they don't have to deal with threaded fittings or where to put them on different engine types.
I am an instrumentation/controls technician and I can tell you, it's all about feedback. Don't put another variable between what you are trying to control and the point where you measure it.
The system works, I just need the sensor getting the proper input. I'm going to try to better insulate the probe from the ambient air. We'll see how it goes. For now, I'm not ready to ditch the current setup.
Here’s what I’ve got, for now. Maybe a little janky, I don’t care. We’ll see if it works. Should help isolate the sensor from the outside air and hopefully get a much better of just the rad temp.
Well let us know how it works. Another solution that wouldn't require messing with the radiator (looks like maybe a stock 2 row?) would be to use this type of hose fitting with the soft start controller: https://smile.amazon.com/American-Vo...dp/B091DKGTVZ/ https://smile.amazon.com/gp/product/B001UPYW1W/
The soft start was important for my setup...when the fan clicked on at idle RPM's dropped considerably, but looks like you've probably got a high amp alternator in there.
One other idea...maybe grease up the part that goes into the radiator with thermal paste? might prevent it from wiggling and help transfer heat.
Last edited by OldBlueMidnight; Dec 8, 2022 at 08:04 PM.
A little update on this. I think I was jumping to conclusions. I live a mile from work and do very little driving more than that. I give it time to get warm in the mornings but, it almost never gets warm for long. I know that's not real great for engines. The other day, I had to run to few different places in town. It warmed up, dash temp sensor rose above 3/4 but not into the red then cooled quickly, When I got back home, I could hear the fan kick on. I think the entire system needs to get warm and the fan will work as normal. It seems like the initial heating up needs to get pretty warm before the sensor gets hot enough to trip the fan. After the initial heating up, when it seems it gets towards the hotter end, the fan kicks on and it never get's that warm again, even when the fan cycles off. Seems everything is good to go. I do think my insulation of the end of the sensor helped. Anyways, thanks for the help.
Dec 6, 2022 | 10:54 AM
