Question about Derale electric fan kit for Jeep Wrangler TJs

jlpierce70

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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.


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?
 
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jlpierce70

jlpierce70

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Chris replied to a thread you are watching at Jeep Wrangler TJ Forum.

Derale fan kit for Jeep TJs
Electric fan kits on TJs are a terrible idea. The stock fan is more than up to the task of cooling the engine, even in the most extreme temperatures.

While I like Derale, running an electric fan is not a good idea. Sorry, I know that's not what you want to hear, but it's the truth.

I hope someone can help you out, as I have no experience with their electric fan kit.



I got an email but don't see this comment?
 
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jlpierce70

jlpierce70

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I didn't put the fan on for any other reason than my Jeep got hot when I had the plow on it.
Keep in mind this is winter in SD. Some days it would be below zero and it would overheat.

If I dropped the plow and picked it up about 4 inches and drove it there was no issue. Its just that the blade blocks the airflow and also makes it work harder pushing the blade through the wind.

It never ran hot any other time. Hottest summer days it was fine, even with the AC going, etc. I tried to make it hot thinking there had to be more to it.
 

Chris

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Chris replied to a thread you are watching at Jeep Wrangler TJ Forum.

Derale fan kit for Jeep TJs
Electric fan kits on TJs are a terrible idea. The stock fan is more than up to the task of cooling the engine, even in the most extreme temperatures.

While I like Derale, running an electric fan is not a good idea. Sorry, I know that's not what you want to hear, but it's the truth.

I hope someone can help you out, as I have no experience with their electric fan kit.



I got an email but don't see this comment?
Yes, disregard that. I missed the part about the snow plow blocking airflow.
 

chad

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It shouldn’t matter if the fan ran all the time the thermostat is what controls engine temperature. I’d probably replace that first. If you’re having problems with Engine Temperatures.
 

jscherb

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There may be something else going on with your cooling system. I've been using a plow in the winters on my LJ for the past 8 years and I've never had an overheating problem - not while plowing, not while doing errands around town, and not while driving reasonably long distances (drove 70 miles round trip somewhere last week and no problem).

The only affect the plow has on the Jeep is that the sensor that the temperature display in the rear view mirror isn't accurate when the plow is on, it reads too high. But the engine temperature has never been out of line.

LJPlow_zpsgxpocl92.jpg
 

chad

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There may be something else going on with your cooling system. I've been using a plow in the winters on my LJ for the past 8 years and I've never had an overheating problem - not while plowing, not while doing errands around town, and not while driving reasonably long distances (drove 70 miles round trip somewhere last week and no problem).

The only affect the plow has on the Jeep is that the sensor that the temperature display in the rear view mirror isn't accurate when the plow is on, it reads too high. But the engine temperature has never been out of line.

View attachment 141557

Love the hard top.
 
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jscherb

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Love the hard top.
Thanks. It's homemade and it has been on the Jeep longer than the plow :).

But not to hijack the thread with hardtop talk, I've been plowing every winter with this Jeep for the past 8 winters and I've never had a problem with the engine overheating, even when the plow is raised (maximum blockage of air to the Jeep) and I'm driving around town or on the highway.

Plowing2017_zpsp5q2yeej.jpg
 
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jlpierce70

jlpierce70

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I replaced the water pump and thermostat a few years ago. I know that doesn't mean I don't need a new thermostat again.

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.

It only gets hot when I'm running down the road with the plow on at highway speeds (65+). If I stop, set the plow down and then pick it up so the plow is only up about 4 inches then I can run as hard and fast as I want without issue. It just isn't too smart to do that!

So since with the plow down enough to allow airflow its fine, but with it up it gets hot it just made since to me that the problem was that the plow blade was blocking the airflow. Now jscherb's story tells me that might not be the issue. When I did the water pump I flushed the radiator and put in new coolant so I don't think the radiator is plugged. But I'm starting to think the radiator is the issue. I don't think the thermostat is the issue because without the plow temp is never an issue. I'm starting to think the efficiency of the radiator isn't up to par.

PS I don't have this on my 99. Just a ghetto plain old mirror!
"The only affect the plow has on the Jeep is that the sensor that the temperature display in the rear view mirror isn't accurate when the plow is on, it reads too high. But the engine temperature has never been out of line."
 
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jlpierce70

jlpierce70

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It shouldn’t matter if the fan ran all the time the thermostat is what controls engine temperature. I’d probably replace that first. If you’re having problems with Engine Temperatures.
Lets assume that the thermostat is working correctly.
If the ideal temp range for the TJ is 195-210 degrees
The thermostat sensor for the kit engages the fan at 199.6 degrees and shuts off at 188.6 degrees.
I think the thermostat is staying open, I don't know if it would close all the way at basically 190.

I think the fan moves enough air (cold winter air) through the radiator that its lowering the temp below the ideal 195-210 range and for no reason. Then it turns off. My Jeep starts to heats back up to around 210 where it wants to be but then the fan kicks back in at 200 and drives it back down to 190.

If I can't figure out why my TJ won't run cool with the stock setup and I have to stay with the fan I'd like to get a thermostat sensor that doesn't turn the fan on until its warmer than 210.

The other thing is that when it engages the fan at 199.6 degrees and shuts off at 188.6 degrees is sitting in my garage with no air flow at all. Real world behavior might be different.

But now that jscherb may have debunked my theory why I'm having problems I'm really more focused on fixing the problem if the plow blade blocking isn't the cause rather than using a fan as a band aid. It wouldn't take me long to put it back to stock.
 

jscherb

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...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...
I'm in Florida right now and believe it or not, I didn't drive the LJ down here with the plow, I drove a different Jeep, so I can't show you a photo of the blade in the up position right now :). But when it's fully raised, the top of the plow is just about at the level of the hood, so it does completely block the slots in the grille.

Everything about my engine and cooling system is stock.

Edit: If you look at my profile picture, my LJ has a CJ grille on it, so the slot area is different but that grille has only been on the Jeep 3 or 4 years, the 4 or 5 years before that I had the stock TJ grille and didn't have any overheating problems then either. Behind the CJ grille is the stock and original radiator.
 
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jlpierce70

jlpierce70

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Thanks for the reply jscherb.

So could be my radiator. Or I wonder if the stock temp sensor thinks its hotter than it really is when there isn't any airflow. But it tells my highly accurate (lol) Jeep temp gauge that its at 210ish about any other time I look at it.

I've got a project in the garage now so I might be a few days until I get to investigate more.
 

chad

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Lets assume that the thermostat is working correctly.
If the ideal temp range for the TJ is 195-210 degrees
The thermostat sensor for the kit engages the fan at 199.6 degrees and shuts off at 188.6 degrees.
I think the thermostat is staying open, I don't know if it would close all the way at basically 190.

I think the fan moves enough air (cold winter air) through the radiator that its lowering the temp below the ideal 195-210 range and for no reason. Then it turns off. My Jeep starts to heats back up to around 210 where it wants to be but then the fan kicks back in at 200 and drives it back down to 190.

If I can't figure out why my TJ won't run cool with the stock setup and I have to stay with the fan I'd like to get a thermostat sensor that doesn't turn the fan on until its warmer than 210.

The other thing is that when it engages the fan at 199.6 degrees and shuts off at 188.6 degrees is sitting in my garage with no air flow at all. Real world behavior might be different.

But now that jscherb may have debunked my theory why I'm having problems I'm really more focused on fixing the problem if the plow blade blocking isn't the cause rather than using a fan as a band aid. It wouldn't take me long to put it back to stock.

I’m pretty sure the fan is doing what it’s supposed to as far as when it kicks on and off. If the motor is going below ideal temperature I think it can only be the thermostat. Do you have an Mopar water pump, thermostat and radiator. If not that will be the first place that I would start. Anyway you can put the original fan and shroud back on. That would also probably be best to.
 

jscherb

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...I'd like to get a thermostat sensor that doesn't turn the fan on until its warmer than 210.
Where is your sensor mounted? Most people think the sensor should be at the engine outlet/radiator inlet, but the best place is actually at the radiator outlet. Here's why:

When you're running at speed the fan usually doesn't need to run because airflow through the radiator due to the speed of the Jeep is enough for cooling.

If the sensor is at the outlet of the engine/inlet of the radiator, the fan will turn on even when proper cooling would have occurred due to airflow at road speed without running the fan. In this case, the engine may run too cold.

If the sensor is at the radiator outlet, the fan will only run when the airflow through the radiator without the fan running is insufficient for for proper cooling.
 
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jlpierce70

jlpierce70

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Where is your sensor mounted? Most people think the sensor should be at the engine outlet/radiator inlet, but the best place is actually at the radiator outlet. Here's why:

When you're running at speed the fan usually doesn't need to run because airflow through the radiator due to the speed of the Jeep is enough for cooling.

If the sensor is at the outlet of the engine/inlet of the radiator, the fan will turn on even when proper cooling would have occurred due to airflow at road speed without running the fan. In this case, the engine may run too cold.

If the sensor is at the radiator outlet, the fan will only run when the airflow through the radiator without the fan running is insufficient for for proper cooling.
87392050_3500740840000622_8244541757371449344_n.jpg
 
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jlpierce70

jlpierce70

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Chris replied to a thread you are watching at Jeep Wrangler TJ Forum.

Derale fan kit for Jeep TJs
Electric fan kits on TJs are a terrible idea. The stock fan is more than up to the task of cooling the engine, even in the most extreme temperatures.

While I like Derale, running an electric fan is not a good idea. Sorry, I know that's not what you want to hear, but it's the truth.

I hope someone can help you out, as I have no experience with their electric fan kit.



I got an email but don't see this comment?


What is the downside of using an electric fan?

If I get this sorted out its easy enough to remove it and put the Jeep back to stock. I'm just curious why you say that? I agree that the stock system should be more than up to the task for what I'm doing.
 
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jlpierce70

jlpierce70

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I had to plow this morning. I drove around 70-75 mph to push the Jeep hard enough to see if it would get warm and it did.

So now I know that the electric fan doesn't help anymore than the stock fan did.

So its got to be the thermostat, radiator or the water pump.

I replaced the thermostat and the water pump about two years ago to the day. Less than 10k miles.

I don't think it would be the thermostat. Just thinking if it wasn't opening up all the way or sticking at times it would get hot at times other than when the plow is on and running down the highway.

But I'm open to suggestions. Where would you guys start? How to test the water pump and the radiator?