Is the original fan shroud still in place.
No with the kit you don't use the fan shroud. It was in place when I had the stock fan in place
Is the original fan shroud still in place.
No with the kit you don't use the fan shroud. It was in place when I had the stock fan in place
I use the Derale kit and had the same experience as you originally. The fan was running almost continuously as it would only shut off at about 185*. The solution was to purchase an adjustable thermostat in lieu of the simple thermal switch provided in the kit. It was about $60 through Derale. Now I have the fan kick on about 205* and off at 195*. Also a bit of advice is to change the provided fuse for an automatic resetting circuit breaker. Been running the fan kit for 4-5 years now without issue.I tried to search but can only find info on Derale transmission coolers.
I've got a 1999 TJ Sahara the the original owner put a snow plow on and left it at their cabin in the garage most of it's life.
I bought it a couple years ago and was thrilled to have found a Jeep in the Black Hills of South Dakota that hasn't been off road!
A TJ isn't' exactly an ideal snow plow vehicle but it's been really useful that's for sure. When I drive it from my house to my cabin even running 55 MPH the plow blade blocks enough air that the Jeep will over heat. So I just added a Derale fan kit.
https://derale.com/product-footer/e...965800353/6-compact-thermal-fan-clutch-detail
OK finally getting to the point of my post... LOL
The thermostat sensor for the kit engages the fan at 199.6 degrees and shuts off at 188.6 degrees. The measurements taken with my code reader.
I've read on here the 4.0L's operating temperature is ~195-210 degrees. Seems to me that the sensor is engaging the fan too soon and bring the temp too low.
So I emailed Derale to see if maybe I have a bad sensor or they packaged the wrong one in my kit. The guy answered back:
"If the temperature was verified at being over 190 and the sensor did not engage it would seem as though it is bad. We will need a proof of purchase sent to us that is within 1 year of the original date of purchase and we can send out a replacement."
In my mind that is going the wrong way, even cooler than what I think it should be at. Am I misunderstanding what is going on?
Anyone else on here have the Derale fan kit?
That lines up with what most will say on here. At least the one who have the knowledge on these things. I would start by doing a complete system flush and visually inspecting for any leaks. Did you replace the thermostat with a non-failsafe OEM unit?So now I know that the electric fan doesn't help anymore than the stock fan did.
I was traveling when you asked for the photo; I'm home and took this one today with the plow raised. Completely blocks the grille....It is reassuring to hear jscherb say he has no problems, I should have posted before I changed to an electric fan.
Do you have the stock water pump on your LJ? Could you post a pic of the blade up from the front of the Jeep just to see if your's maybe doesn't cover the same area as mine does? Just trying to eliminate different variables that might be affecting my Jeep...
What is the downside of using an electric fan?
Could it be possible to design an electric fan that mimics the flow numbers of the stock one?I don't have airflow numbers for the stock fan, but here's some general fan application info:
An electric fan is limited by how much current you can safely draw from the vehicle's electrical system without overtaxing it and draining the battery. At 12 volts, to power a 1hp fan would require nearly 70 amps, where as you can imagine a fan pulling 1hp off the engine would never be noticeable.
There are plenty of vehicles out there running electric fans with perfectly reliable and effective cooling systems, but radiators and fans are designed as a system. So a car designed to have an electric fan can easily add more fin surface, depth, etc to the radiator to make up any heat transfer lost to the reduced fan power and airflow.
It's when a radiator designed to use a mechanical fan gets matched with an electric fan that in all likelihood doesn't move as much air that we get in trouble.
Could it be possible to design an electric fan that mimics the flow numbers of the stock one?
That’s what I figured. I like knowing the science behind the commonly recommended routes.It's definitely possible, but is it going to have a reasonable current draw?
the stock fan certainly leaves some room for efficiency improvement, so it's conceivable you could match the airflow with slightly less power, but here's just no getting around physics.
The highest airflow Derale fan I could find in 3 minutes on their website was a 17" that's advertised as 2400cfm, 23A and 0.35hp.
The commonly swapped Taurus electric fan is cited as moving 4500cfm and drawing about 33A. Assuming an 80% efficient motor and a 50% efficient fan (which is typical for an axial propeller fan and giving some extra credit on the motor) that works out to 0.53hp at a pressure drop of 0.3 in H2O. To match that with a prop fan would only pull 0.42hp from the belt. This is probably about the limit of what an electric fan can do without major electrical considerations, and again I don't have the stock airflow numbers but being in excess of 4500cfm is well within the realm of possibility.
Power input for a given fan increases with the cube of airflow. So just a 25% increase in airflow almost doubles your current draw.
The great thing about an engine driven clutch fan is that more airflow is basically free...there's no extra material because you just have to pitch the blades a little deeper, and it's really small potatoes on your EPA mpg because at speed the clutch is disengaged. The first limit you'd run into is the power transmission capacity of the serpentine belt.
I use the Derale kit and had the same experience as you originally. The fan was running almost continuously as it would only shut off at about 185*. The solution was to purchase an adjustable thermostat in lieu of the simple thermal switch provided in the kit. It was about $60 through Derale. Now I have the fan kick on about 205* and off at 195*. Also a bit of advice is to change the provided fuse for an automatic resetting circuit breaker. Been running the fan kit for 4-5 years now without issue.
That lines up with what most will say on here. At least the one who have the knowledge on these things. I would start by doing a complete system flush and visually inspecting for any leaks. Did you replace the thermostat with a non-failsafe OEM unit?
Some of the reviews I've read about the kit is that the fan goes out after a year or so. That makes sense if you use your Jeep for a daily driver the way the fan is always turning on, running for a few seconds and off again. I have to think the start up is the hardest on the fan, the relay, and the fuse.
Good to hear there is an alternative to the basic temp sensor switch.
I use the Derale kit and had the same experience as you originally. The fan was running almost continuously as it would only shut off at about 185*. The solution was to purchase an adjustable thermostat in lieu of the simple thermal switch provided in the kit. It was about $60 through Derale. Now I have the fan kick on about 205* and off at 195*. Also a bit of advice is to change the provided fuse for an automatic resetting circuit breaker. Been running the fan kit for 4-5 years now without issue.
There's a different school of thought on what you said about the location. The temperature of the coolant after it exits the thermostat housing (where the factory temperature sensor is located) is most indicative of the engines operating temperature. You want to control the engine temperature not assess the heat transfer of you radiator, so the upper hose, radiator or thermostat housing is the most accurate location. The manufacture suggests this as well.The electric fan functions to cool off the radiator.
Therefore, the temperature probe should be placed in a position to measure the performance of the radiator as it lowers the temperature of the coolant.
That place is the lower radiator hose where the coolant leaves the radiator and enters the engine.
Any other spots will cause the fan to run more often than it needs to, which effectively eliminate the entire purpose of an electric fan.
Which manufacturer?There's a different school of thought on what you said about the location. The temperature of the coolant after it exits the thermostat housing (where the factory temperature sensor is located) is most indicative of the engines operating temperature. You want to control the engine temperature not assess the heat transfer of you radiator, so the upper hose, radiator or thermostat housing is the most accurate location. The manufacture suggests this as well.