Coolant Temps Testing: Fan/Clutch vs. Flex-A-Lite 475 Electric Fan

[Daless2]

Hi Folks,

A few months ago I won in a raffle a new Flex-A-Lite II 475 electric fan for my Jeep TJ.

Here are my notes and the results of some testing I did on this fan and the original equipment mechanical fan/clutch on my Jeep.

My TJ is a 97, 4.0L with 5sp and A/C. There is a winch in front of the grill. I also have a 3-core radiator, a 195 degree F thermostat and to the best of my knowledge a perfectly functioning fan/clutch.

All tests were done in Kentucky at humidity levels above 80%.


First Impression:

The fan is well built.


Second Impression:

This Sucks!

Apparently the same fan kit is sold for both TJ?s and YJ?s.

In order to install this fan in my TJ I had to ?Snail Mail? an ?in-the-box coupon? to get the required bracket needed to hold the overflow bottle. This took 11 calendar days to arrive. (Had I purchased this fan for $200 or needed it NOW I would have been a bit more ticked off.)

Third Impression:

This Sucks!

The passenger side bracket that holds the fan to the radiator does not provide clearance for the A/C Condenser lines. This required a 1-inch notch to be cut in the bracket. One would think they would notch all these brackets to start with.

Remember the recovery bottle bracket I waited 11days for?

The two boltholes in this bracket did not line up with the drivers side bracket that holds the fan to the radiator. Misalignment was better than 3/8 of an inch. (This is their bracket not lining up with their other bracket.)

In addition, this bracket was far too wide. Once I drilled the holes out so it would bolt on I found the bracket to be ? inch too wide. It was hitting the inner wheel well sheet metal.

I trimmed the width of the ?snail mail? bracket down by ?-inch.

All this bracketry appears to be laser cut. I would imagine it wouldn?t be too difficult to get it right. Nor was it that difficult to correct on my end, but?.. That is indeed what I had to do.

The instructions that come with the unit instruct you to bend the radiator fins in a certain spot and then insert the fan temperature-sensing unit.

Nope! This isn?t true.

Apparently the Flex-a-lite folks updated the design, and the fan temperature-sensing unit is now mounted and incased on the fan housing, but someone forgot to change the directions.

I dislike things like this intensely. For what this thing cost, I would expect everything to fit and be right out of the box.

To start with it was safe to assume I was not exactly overwhelmed with a vision of quality here.

That said here are the results of my testing.


Testing Equipment:

As some of you know, I have a friend who owns an automotive testing lab with all kinds of testing equipment related to temperature recording. Over the last few weeks I have borrowed some of this equipement and performed the same tests on both the Mechanical Fan/Clutch and the Flex-a-lite II fan.

The equipment I used had one (1) in-fluid temperature sensor placed inside the upper radiator hose where it meets the radiator.

This sensor recorded time and temperature data, ever 3 seconds, to a small hand-held data collection device. All temperatures are in Degrees F and recorded to an accuracy of 1/10 of a degree F.


Types of Tests:

I performed three different tests on both the original equipment Mechanical Fan/Clutch and Flex-a-lite Electric fan over several weeks. Each setup went through these three tests multiple times.

At Idle Test:
This test measured the Highest and lowest coolant temperatures with the Jeep idling in my driveway for 15 minutes after a 5 minute warm up period.

Stop and Go
This test was a 6-mile stop and go, inner city drive, after a 5 minute warm up period. Obviously each test was not exactly the same as stoplights most likely did differ. But the course was indeed exactly the same each time. Max Speed was 25 MPH.

Highway:
This test covered a distance of 18 miles on Interstate 75. Nine miles down the interstate, off the exit, turn around and nine (9) miles back. Highway Speed maintained at 65 MPH.


Test Notes:
As I stated, each of these tests was conducted multiple times. The data I am sharing is the data I have for those days when the outside air temperature was the hottest. for each setup.

Also note, the outside air temperatures are different for each of these tests, and what was being tested, so please take that into consideration.

Air Temp = The outside air temperature range during the test

Highest = Highest recorded coolant temperature during the test.

Lowest = Lowest recorded coolant temperature during the test.

Average = Average coolant temperature of all recorded temps during the test. (This is not the average of the High/Low temps, but rather of hundreds of temps.)

Hi/Low Delta = The difference in degrees between the Highest and Lowest recorded temps.



Here are the results for these tests with the Air Conditioning OFF.




At least as far as my testing efforts go in every case the electric outperformed the mechanical fan clutch. What is also interesting is the electric test occurred when the air temperature was five (5) degrees F higher.

However, interesting to note is the delta between high and low temps is slightly greater for the electric.

In support of the information Joe West posted about the inaccurate TJ water temp gauge, my gauge never moved past just touching the Zero on the 210 on the gauge face at any time during any of these tests.

Here are the results for these tests with the Air Conditioning ON.




Big difference here folks.

I think that is because the electric fan is on at all times when the A/C compressor clutch is engaged. Where as the mechanical fan clutch has no means of providing additional airflow through the radiator.

Also note, the electric fan has a thermostat that can be adjusted to tune the coolant temperature in.

Off Road Test

I did not think to test the coolant temps with the original mechanical fan/clutch, so I have no data to report. I did however record these temps with the Flex-a-lite fan.

I would not in any way call this hardcore off roading, but it wasn?t a cakewalk either. This temp data was collected during a 2.5 hour off road adventure, which covered 1.7 miles (about 0.7 MPH). Outside air temp varied from a low of 90 degrees F to a high of 97 degrees. F.




Current Impression:

OK, I?m impressed.

I was indeed surprised at the effects. In my mind, and at least as far as my testing has gone, this puller fan (2340 CFM) does indeed outperform the stock mechanical fan/clutch.

I cannot say I feel any difference in power as a result of this change.

I do believe there may be a minor improvement in MPG, but I do not have enough overall miles on it since this change to make this statement with any degree of warm fuzzy feeling.

I have no idea how well this setup will hold up over time. It does appear to be very well built but time will tell.


Hope some folks find this useful.

Frank


PS: I plan on installing a second, under dash coolant temperature gauge, as I just can?t live with the level of inaccuracy of the stock TJ gauge.

[Dan-H]

Thanks for the report Frank.

Once again, it is nice to have factual data points to help ground the claims.

A few weeks ago during our heat wave we had a couple days of 105-110+ or so. (cool by arizona standards) but I found the A/C in my TJ was not really doing well, nor was the AC in my wifes 4-runner.

I was thinking about adding a pusher fan to the front to help with the AC but wasn't sure how it would affect or impact highway cooling.

if I sent you a pusher to test, would you consider re-installing your stock fan and shroud and re-running the temp tests LOL j/k

- Dan

[Daless2]

Hi Dan,

Funny you should mention the A/C Temp. Earlier today Blaine and I were discussing this. While I have no numbers to back it up, the A/C Temp on my TJ is clearly colder then it was before.

Heck, it was 100 degrees (Unusually hot these last four or five weeks) here on Sunday, and with the soft top up and the air on I had to turn it down a notch or two to be comfortable.

Like I said I don't have any real numbers but I am tempted to measure it with the electric fan, then put the Fan/Clutch back in to measure it again.

When the electric fan is running the volume of air it pulls through the condenser and radiator is impressive.

I can holds a small American Flag 2 feet in front of the grill and it gets pulled straight out. While I didn't do this with the stock setup I doubt it would even move it.

Hey Dan send me that pusher. I'll test it. Can't promise I will send it back though!

Have a great day.

Frank

[Stu Olson]

Frank,

Very good data indeed and I have no doubts in your methods of testing, etc. Nice job.

I will add that the fan used by JoeW in his setup was the type that is mounted to the front of the condesor coil (literally). Since he mounted it, and another Phx Jeeper did his, we have heard from a couple of other local Jeepers that the mounting style used will eventually rip the tubs in the condesor coil! OUCH! I was not happy to hear that and am very glad that I did not go that route had I been considering it.

It sounds as though the mount on yours keeps it off the radiator fins and you'll not suffer this problem down the road.

[Daless2]

Data Mining

This evening I went over to Kevin?s lab to get some lesson in data mining.

The data I shared above reflected the coolant temperatures captured for one set of tests when the outside air temperature was the hottest. This was my attempt to show the worst case that I had collected.

All the testing I did occurred over a four week period, and each test was run multiple times. During this process the data collection unit I used literally recorded more then 100,000 data elements. Tonight Kevin helped me extracts some of this data and put it into what is hopefully a useful format.

In the tables below you will find averages for all coolant temps in any given test.

For example:
I ran the Idle Test without A/C five (5) times for the mechanical fan/clutch and seven (7) times with the electric fan. Time, Air Temperature, and Coolant Temperature data elements where captured every 3 seconds, during each 15 minute test.

The same was true of all other tests. Lots and lots of data here folks.




How to Interpret these Tables:

Lets look at The A/C OFF Mechanical Fan/Clutch information in the table below.

The average air temperature for all tests I performed in this category (A/C Off, Mechanical Fan/Clutch), on all the days I tested was 87.9 F.

The average coolant temperature for ?All Idle Tests? on all days was 230.6 F.

To the right of the Average Idle Test coolant temperature you will see 3 columns labeled ?+/- 2?, ?+/- 3?, and ?+/- 4? .

These columns give the Percent of all Temperatures recorded, for each test, which fell within Plus (+) or Minus (-) Degrees F of the Average.

For example:

Take a look at the Idle Test results line again.

The average Idle Coolant Temperature for the Mechanical Fan/Clutch was 230.6F.

The next column, ( +/- 2) is telling you that:
72.7 % of all coolant temperatures recorded for all Idle Tests where within 2 degrees of the average.

In other words,
72.7% of these temperatures fell between 228.6 F and 232.6 F.

(If 10,000 temperatures were recorded during all the tests in this category, 7,200 of these temperatures were within 2 degrees of the Average Temperature.)



The next column,
(+/- 3) is telling you that 86.3 % of all coolant temperatures recorded for all Idle Tests where within 3 degrees of the Average.

In other works,
86.3 % of these temperatures fell between 227.6 F and 233.6 F.

And so on.

I hope I explained that clearly. If not I will try again tomorrow.


Data Extract:

Here is the data extracted from all the coolant temperature data collected. Hopefully you will find it in a format that might generate some thought and questions, and perhaps even a revelation or two. I still need to study this to see what I might pull out of it.







Have fun, and let me know what you think.

Frank

[Daless2]

Thanks Stu,
I try like heck to be as accurate as possible when doing things like this. Else I am expending energy to get flawed information and that sure as heck doesn't help me or anyone else out.

This unit touches only the inside of the radiator with a foam gasket to form a seal for the fan shroud. The unit itself bolts to the original fan shroud mounting location.

I have a ton of data that I collected on this, I just put some up in what I hope is a digestible form.

Have a great evening,

Frank

[StealthTJ]

Frank, are the testing results that you show with either the mechanical fan only or the Flex-A-Lite only (not in congunction with the mechanical fan) ?



Fred

[Daless2]

Hi Fred,

Yes you are correct. The tests I did are with one or the other, not both at the same time.

The Flex-a-lite is a puller and it sits in the space behind the radiator where the stock clutch/fan would live. It's actually quite tight.

Last week I did some testing on the in-cab A/C air temps.

It seemed to me that the A/C was blowing considerably colder air with the electric so I wanted to see if it was true or just my imagination.

I put the fan/clutch back in and tested, then I took it out and put the Flex-a-lite in.

It is true.

The A/C air at the center dash top is much colder.

I am guessing this is becuase the Flex-a-lite fan is on whenever the A/C compressor clutch is engaged. This setup clearly sucks more air through the condenser and radiator then the stock fan does.

A/C center console air vent measure no less then 5.6 degrees (This happened on the highway) colder and no more then 11.3 degrees F colder (This happened durring stop and go driving. I did not test it at idle).

All tests were done on the same day with the fan/clutch first when outside air temp was 89 degrees F. The Flex-a-lite test was done in the late afternoon when outside air was 94 degrees F.

I'm convinced.

Frank

PS: There is one lie on the box this unit came it. It says "Quieter then a belt fan" NOT TRUE. You can barely hear in in the Jeep, but outside it is loud.

[lynn]

Frank
Lots of good performance data.
One thing missing is life cycle data. I know, kind of impractical to buy one and run it until it dies, unless you work for Flex-A-Lite

Regarding life cycle, I installed (on my '71 CJ/225 V6) a 14" puller (don't recall model #) in '97. In '99, after <5K miles, the bearings went out. In 90+ temps, in a traffic jam, 100 miles from home
Although the Jeep was used offroad during that period, at no time were the fan blades or motor submerged or subjected to mud, etc.
So I posted the event to a variety of boards. And to my surprise, the Flex-A-Lite owners who responded said they got ~2 yrs max out of their fans until the bearings are toast.
That trend appears to continue to this day. I just read a post in the past week or so describing the same scenario.
Personally, I wouldn't touch a F-A-L fan again.
I have heard reports that SPAL fans seem to hold up the best, but I have no experience with them. I went back to a simple mechanical fan, on a FlowKooler water pump. Seems to be working quite well.

[Daless2]

Hi Lynn,

Yes your absolutely right. I have no clue how long or short this unit will hold up, but I appreciate the heads-up based on your experiences.

I will definitely keep a close eye on it and at the first sign of a problem the original fan/clutch will be going back in. Hopefully I won't get bit like you did. (5k sure isn't very many miles to get out of any product, let alone one as critical as this.)

Thanks again for your input.

Frank

[JLemieux]

Frank,
Your data and experience is interesting. I installed the same fan and couldn't keep my Jeep from overheating. I have additional trans and power steering coolers in front of my radiator but it didn't come close to cooling my Jeep.

[Daless2]

Hi John,

Don't you just love it when two people get two exactly opposite results!

I wouldn't doubt your experiences in any way. In fact I think the anomaly is very interesting and perhaps worth trying to figure out what's different or what causes two completely opposite results.

I have at times removed the electric to reinstall the stock fan/clutch. But I did this only so I could set my Jeep up for "other" temp tests I was running and wanted to get my Jeep as close as possible to the setup most folks would have on their Jeeps. Yet I have always put it back afterwards.

One of the things I feel confident in saying is that the electric fan does indeed pull more air through the radiator, (when the fan is on) then the stock fan. I base this observation on the simple flag test. (Putting a small flag in front of the radiator and having it stand at attention with the electric, but not with the stock fan/clutch.)

I don't really know for fact that it moves more air, as I can't find any specs on air movement for the stock fan/clutch, just from this observation in this rather simple test.

Since posting this original thread I have done a lot of testing (playing around with) "evaporative cooling" and it's effects on coolant temperatures. Perhaps there is an answer of some type in these results as well. While I don't know for sure what's going on on your end I can tell you that generally speaking the more humid the air is the better it's cooling effect. To a point. Also, the lower in altitude, the more humidity that can be carried in the air. There is also an effect of cooling based on how close to the dew point temperature the air is at.

While I don't have any way of explaining our 180 degrees differences in experiences, perhaps there is some relationship to humidity.

I do know that if you start with very dry air, and inject water in it, to a point, the efficiency of the cooling goes up dramatically! (Evaporative effect.)

Thanks for posting your experiences with this John. Maybe if we put our heads together we can come up with a reasonable explanation that would be understandable and valuable to others so they can make better choices for their own application.


Have a great day.

Frank

[mrblaine]

John and Frank, perhaps you could each identify the radiators you are using?

[JLemieux]

Originally posted by mrblaine
John and Frank, perhaps you could each identify the radiators you are using?

At the time I tried the electric fan, I had a 2 row cooper/brass radiator. My Jeep overheated at idling speeds with A/C on and temps above 85 - 90 degrees with the stock fan and clutch. With the same radiator and the electric fan, it would overheat under the same conditions but would also overheat pulling a long grade at highway speeds.
I have since changed to the 7 blade fan and heavy duty fan clutch offered by Jeep and a factory aluminum radiator. When this fan clutch engages it will pull in a small child walking close to the grill. Considerably more air than the electric fan did. (My opinion - no test equipment) If I increase my idle for a minute the temp will come right back down to normal.
I never did try the electric fan with the factory radiator.


Frank, does your Jeep have a 5 speed or auto trans? I have a 700R4 Auto with significant trans and power steering coolers.

[Daless2]

Hi John, Hi Blaine, that's a good point.

Mine is a 97 TJ with 5sp and A/C. There is a winch in front of the grill.

The radiator is a 3-core aftermarket about 1/4-inch thicker then the stock radiator. It is NOT aluminum, but rather the copper/brass combo. The thermostat is a stock 195 degree F unit.

When I started this testing effort it was primarily to "test," in that I wasn't having any cooling issues at all. I never have on the TJ.

Hey John, I like that line "When this fan clutch engages it will pull in a small child walking close to the grill" Wish I had thought of it. But I'm not proud, I'll use it sometime in the future!

Just as you have described above, the difference between the stock fan and the Seven blade fan, I notices the same in air flow difference between the Stock fan and the Electric. To my observation this was a rather large and remarkable difference in air flow. My only real test for this was what I observed by placing a small flag in front of the grill, maybe a foot away.

The stock fan wouldn't hardly move the flag, the electric made it stand right out. I was impressed with this, yet unable to actually identify How much more air it moved.


I'd be real interested in the part number for that Jeep seven blade fan if you have it handy John. I'm sure others might get a significant benefit out of it too.


Perhaps your Auto Trans and the effect of cooling the fluid also explains some of the differences between your observations and mine.

I think there may be too many variables for an accurate comparison. What worked on mine, compared against itself may only be one scenario, as we can obviously see when compared to yours.

Did you notice (observe) any differences in air volume being pulled through the grill when comparing the stock to the electric? I ask that becuase at least on my Jeep is was and is very noticeable.


Also, I generally run only 32 inch tires, 4.10 gears. Off road my Low range is 3.8

Hmmmm......

Frank

PS: I do not use a P/S Cooler. So far I haven't had a need for one, but I am playing with a new design, using evaporative cooling that can be applies only when needed.

[Robert J. Yates]

Originally posted by JLemieux
I have since changed to the 7 blade fan and heavy duty fan clutch offered by Jeep

John,
Would you be interested in providing either the part numbers or the parts for this conversion to me?
Thanx.

[JLemieux]

Originally posted by Daless2

I'd be real interested in the part number for that Jeep seven blade fan if you have it handy John. I'm sure others might get a significant benefit out of it too.


Perhaps your Auto Trans and the effect of cooling the fluid also explains some of the differences between your observations and mine.


Did you notice (observe) any differences in air volume being pulled through the grill when comparing the stock to the electric? I ask that becuase at least on my Jeep is was and is very noticeable.

These parts are from a service bulletin for 2000-2001 TJ with auto trans. The fan will fit on earlier TJ's with some modification to the mounting holes. I don't know about later models. The fan clutch will not work on the earlier models unless the water pump is changed to the later one. I have not done this, but I assume it will work.

Fan: #55037650AA
Fan Clutch: #5066177AA


My trans cooler does not plumb into the radiator for just that reason.

I didn't notice a big difference between the stock fan and the electric fan at idle, but I didn't pay that much atention to it. I do know that when the fan clutch is engaged and the RPM's are increased, there is considerably more air being moved by the mechanical fans (5 or 7 blade). This doesn't help me at idling speeds and that is where my problem is.

[Robert J. Yates]

Shoot,
I just did a water pump so I think I'll try just the fan first and see what happens. My problem is not at idle, its on the freeway with the a/c on and pulling a grade. Thanx

[Stu Olson]

Robert....me too. I can run around town all day in mid-summer without over heating issues. But out on the freeway....it slowly climbs up when I have the A/C running and I have no auto tranny heat load, as you know.

I wonder if it is the fan or the clutch that contributes more to the increased air flow?

[Robert J. Yates]

I've already swapped out the stock fan clutch for a Hayden aftermarket and got a slight improvement. The stocker wouldn't even hold a shop rag against the grill. You might want to look at that as someplace to start Stu. I did that swap 2 years ago so who knows, maybe its no longer up to snuff - I should test that probably.

[Daless2]

Thanks for the part numbers John.

I have to look into then.

If I understand things correctly, with a bit of modification the 7 blade fan will fit an earlier year TJ fan clutch

But;

In order to use the new fan clutch you listed the water pump needs to be replaced with the new pump and new mounting system

Yes??


While this time of year isn't very good to be doing any coolant temp testing I think in the coming summer I will take this one up again.

I'd like to see what happens if the fan clutch is disabled, meaning intentionally locked up. I suppose I could speculate how it would act but I think I'll test that setup.

I would think if the clutch was slipping prior to it normal setting that the coolant would get a bit more warm then it should. Then, if additional load is added there may be a higher potential to overheat. Pure speculation, or perhaps just me thinking out loud.

Frank

[JLemieux]

Originally posted by Daless2

If I understand things correctly, with a bit of modification the 7 blade fan will fit an earlier year TJ fan clutch

But;

In order to use the new fan clutch you listed the water pump needs to be replaced with the new pump and new mounting system

Yes??

Yes

[JLemieux]

Robert & Stu....
I have a customer in the shop that has your same problem. He has the factory aluminum radiator, 7 blade fan and H.D. fan clutch from Turbo City. He still has the problem of running hot on the highway during the summer time.
I am installing an auto trans in his Jeep now but also a 2 row all aluminum radiator. I'll have to wait untill summer comes around to find out if this solves his problem.
What modifications have you two made that might affect air flow into the radiator and out of the engine compartment?
I would like to compare them to his Jeep and see if there is anything in common.

[ChrisK]

I'm not sold that the Turbo City HD fan clutch does much. I installed one and didn't notice much difference. I'm in the same boat as Stu and Robert.

Where are you getting the 2 row aluminum radiator?

Chris

[Robert J. Yates]

John,
Typical TJ - 6, auto, 35's with a winch, lockers ect - you've seen it and worked on it (auto tranny re-seal and vent modification) - nothing really special other than it has always wanted to run warm.

Its never overheated but I feel like I have been chasing the same dog for a long time now. 3 core all metal radiator and new fan clutch made a difference, lowering the winch made a difference, RS t-stat and new water pump helped (alot actually, I think the original stock pump was not 100%), auto tranny cooler (frame rail mounted under skid) helped, but none of those ever leave the Jeep with enough reserve which is quite concerning.

Everything I do has to be done with the idea in mind that it will alter the running temp. Typical was the installation of the PS cooler in the grill - its a small 7x9 plate cooler but it immediately affected the airflow into the radiator enough so, that the increase in running temp was noticable on the guage. My next move is to investigate an oil cooler which Frank will be bringing out for me. If that doesn't help and the 7 blade fan is ineffective, I will probably have to pull the a/c condensor and radiator and find a new home for the PS cooler.

[TJP]

Originally posted by Robert J. Yates
John,
Typical TJ - 6, auto, 35's with a winch, lockers ect - you've seen it and worked on it (auto tranny re-seal and vent modification) - nothing really special other than it has always wanted to run warm.

I have the same setup, but no winch. I also have the stock radiator and no overheating problems. Maybe this is a winch related problem, airflow being forced up and over the hood instead of through the radiator?

[Daless2]

Have any of you guys given any thought to the hood louvers?

Also, I would imagine it would be very easy to hook up a heater core to the heater core hoses and a small 12 volt fan to get rid of a lot of engine heat. Especially if yours is running right on the edge of "high".

Frank

[JLemieux]

Originally posted by ChrisK
Where are you getting the 2 row aluminum radiator?

Chris

Custom Aluminum Radiators in Kingman, Az.

This unit is one that is used for V8 conversions in the TJ. It is a cross flow instead of a down flow and not an easy install. For a stock 6 cylinder it is a very tight fit against the fan clutch (1/2" - 5/8") and the stock fan shroud does not work without modification and additional mounting. Urethane motor mounts are a must, to keep the fan clutch from hitting the radiator.

[JLemieux]

Originally posted by Daless2
Have any of you guys given any thought to the hood louvers?

Also, I would imagine it would be very easy to hook up a heater core to the heater core hoses and a small 12 volt fan to get rid of a lot of engine heat. Especially if yours is running right on the edge of "high".

Frank

I think I will do the louvers, but more for the reason that it looks cool and different. If it helps my low speed heating problem than yea for me.

[JLemieux]

Originally posted by TJP
I have the same setup, but no winch. I also have the stock radiator and no overheating problems. Maybe this is a winch related problem, airflow being forced up and over the hood instead of through the radiator?

Had my customer remove his and he noticed no difference.