Is the stock electric fan enough to cool on its own?

[ZmOz]

Re: Yes, I decided a long time ago I was going to do this. What I am, and was, asking her

If you wish to waste your time and money trying something that many of us have already wasted ours on and dont wish to listen to experience then go ahead and do it but don't waste our time asking the questions if you aint gonna listen

You are about the only one who had problems with it, I don't know what the hell you were doing but you were doing something wrong. Like I said, take a look at Dino's website. I beleive he knows more about the 4.0 than any other one person on this or any other forum. He lives in a country where it gets to 120 degrees in the summer, and he says it works great even with the AC on. Not only is Dino an expert, but a nice guy who has helped me with several other problems, and I will take his word for it that it works.

 

[rockwerks]

Its your money...have fun....

His driving is Saudi Arabia is quite different than ours here in the US, SA is pretty flat and the electric fans work fine till you start puling hills or long stretches @ 75 on the highway.

We used an ANEMOMETER ( used to check air flow/ wind speed) to check air flow and the stock set up moved nearly 30% more air than any of three electric setups we tried. single fan, dual fan,( 2-12") and triple fan (1-10" 2-12")

In oregon they might work jsut fine, jsut dont try to cross the rockies

 

[MJmk]

Re: I did it and it was Ok.

I shorted out my flex a lite 110 fan during a trip and had to go 200 miles in 75* weather with just the factory electric aux fan running. I had it on a manual switch, so it didn't wait until the 218* ECU limit kicked it on. It ran about 210 all the way home (highway driving mostly). The flex a lite 110 pulls about 1.5X the amount of air as the factory electric fan. Both together work well. I wouldn't expect the little factory fan to cool all by itself in all seasons, regardless of where you drive it.

You did it and it was OK? What's up with your post about overheating in your thread in OEM tech "Has anybody towed with an XJ?" I'd link it if I knew how!! ( I'm a newbie :dunce: )

 

[vintagespeed]

Re: Yes, I decided a long time ago I was going to do this. What I am, and was, asking her

If you......dont wish to listen to experience then go ahead and do it but don't waste our time asking the questions if you aint gonna listen

Man, if I listened every time somebody said "dont do it, it ain't gonna work", my Heep would still be at 4" lift & 32s. And as far as 'experience' goes, I've been wrenching going on 20 years so that arguement don't float. I know, I know a 3 link & 38's will never work, full width axles are a waste of money, you'll never get a York to fit under the hood of an XJ, a 14 bolt is too heavy for an XJ, blah blah blah blah.

 

[rockwerks]

OH SH*T!!!! you mean teh three link with coil overs I jsut built wont work....HMMMMM...I guess I sould go back to the four link.

This fan topic is just one that has been beaten to death and only one guy out of hundreds says it will work.

The flex a lite 110 pulls about 1.5X the amount of air as the factory electric fan.

and that is still 30% less than the factory clutch fan

and how did you figure the 1.5X air increase?

 

[vintagespeed]

Someone must've really crapped in your Cherrios this morning. I wish it was me.

So what do you tell GM, Ford and the imports than run dual fans? They're all wrong but you're right? And you're saying that you've tested EVERY factory dual fan shroud setup out there (probably thousands) and none of them work on the XJ radiator?

.

(Post Moderated: Personal insult removed.)

 

[TiRod]

I'm sorry this hasn't worked for some. Obviously something is different from one application to another. Maybe the number of cores in the radiator, or what year cooling system. If we take the time, we know that earlier systems were improved over the years, and that some of the more subtle features aren't easily seen, but can be more important.

We do know the following: 160 is too low, don't trust the gauge, and there are cooling systems out there that have no mechanical fans. Modifications and upgrades are entirely the responsibility of the owner. Sometimes they don't work - and everyones' experience is valuable in understanding just what can be done.

I was told you can't put a top loader 4-speed in a 6 cylinder '66 Mustang - you can't - not until you pick the right parts and be the engineer. It cut a car length in the 1/4, and later the 302 bolted right up.

Wish I had that Granada 9" back.

 

[Lucas]

my electic replacement is a 12" imperial from autozone. rated at 850 CFM it did great in 95 degree weather, ac on, in the woods wheeling in 4low and high rpms.

I think a lot of it has to do with how much air is actually pulled THROUGH the radiator. The new electirc sits all of 1/8 of an inch off the fins of the radiator, and with the built in shoroud, virtually all the air it pulls has to be pulled through the fins. The mech fan , even with the shroud, has a lot of space to just circulate air rather than pull it in from the outside.

 

[Eagle]

As for the electric fan idea, it takes a hell of alot more energy to spin that big old metal fan blade and viscous clutch than it does to spin an electric fan... Not only that, but the mechanical fan is ALLWAYS putting a load on the engine. With an electric fan it will turn off at high speed, putting absolutely no load on the engine.

I'm not doing this for speed, although that's a nice side effect, I'm doing it to save ~2mpg.

First, please clean up your language. You came here asking for advice. It's pretty rude to insult the people who take the time and trouble to answer you.

You don't seem to understand how the XJ primary fan works. The viscous drive inherently reduces drag at higher speeds. However, the XJ fan clutch also has a thermal spring -- it's basically free wheeling until the heat rises, then the bimetallic spring locks it up to move more air. Whether or not dual electric fans will work, and remember, you asked about dual stock fans, not aftermarket units), I don't think you are going to save anywhere near 2 MPG. Probably more like 0.2 MPG.

 

[Eagle]

It is a proven fact that an electric fan moving the same amount of air will use WAAAAAAAAAAY less power, as well as making the water pump bearings and the belt last longer...

Whoa!

Neither of these is a proven fact. MaXJohnson already explained that it takes 'X' horsepower to move 'Y' CFM of air. That horsepower has to come from somewhere, it ain't free. If you think your electric fan only uses 1/4 horsepower to move enough air to cool the engine -- then your mechanical fan is also only going to use 1/4 horsepower to move the same volume of air. That's basic physics.

Second, the mechanical fan doesn't run on the water pump, it runs on a separate pulley. The serpentine belt requires the same tension whether or not there's a fan on that pulley, so the lateral loading on the water pump bearings will be identical. Neither the belt nor the water pump will last a single nanosecond longer as a result of this mod.

 

[Kejtar]

Re: Re: Yes, I decided a long time ago I was going to do this. What I am, and was, asking her

Like I said, take a look at Dino's website. I beleive he knows more about the 4.0 than any other one person on this or any other forum.

ZmOz.... man.... not to take away from Dino... but I can think of 3 people here on that can take appart the 4.0 with their eyes closed and one hand tied behind their back and by touch diagnose problems... ok, maybe I'm exagerating a bit, but to say the least Dino is rather new to the 4.0 while there are people here that have worked with it since day 1. Also there are different uses and applications for our XJ's and his seem to be primarily racing where the speed ends up aiding the fans while here... well, hit LA traffic and you're NOT moving, and yes, it gets HOT here as well (maybe not 120, but I think we breached 110+ this summer).

Now if you're thinking this will work, you have to do this as a trial and error thing.... get a fan, test it... hit a trail or two (on a hot day), idle in a hot day's traffic and observe results.

Finaly the fact that someone on JU says that things work, doesn't mean much..... and I'll leave it at that (just mine and quite a few others observation throughout the time).

Kejtar
P.S. oh yeah.... people.... control your language and tempers..... or do you need an extra colling fan in front of the comp as well for yourselves?

 

[MaXJohnson]

Hot topic !

Sometimes they work, sometimes they don't ???

Is it time to invoke the "every Jeep is different" rule?

How about the "every Jeep's maintenance history is different"

Some guys consider running electric fans because they are having overheating problems and are grasping at straws to solve their problem. These applications are likely to fail.

Some guys experiment with the cheapest junk yard fan they can get their hands on. These applications are likely to fail.

Start with a Jeep that doesn't overheat, determine the CFM necessary to provide sufficient cooling and then install a quality fan that meets the specs. This application will probably succeed.

What we rarely see in threads on electric fans are the facts and figures neccesary to make some logical decisions.

How much air do we need? 10cfm/hp? 15cfm/hp? 20cfm/hp?

Let's say the 4.0 requires 15cfm/hp. 180hp x 15cfm = 2700cfm. Where does this air come from? The radiator doesn't care. At freeway speed, pushing through the air should do the job. At lesser speeds, the fan has to provide the necessary air flow. Generally, the engine is not putting out maximum hp so less than our example 2700cfm is required to do the job.

The mechanical fan will vary the amount of air delivered based on engine RPM. The blades are designed to operate over this wide RPM band, not terribly efficient at any given RPM, but pretty good overall. This fan will never see it's stall speed because the viscous hub limits maximum RPM. This also limits the maximum HP required to a factory determined level. This is probably around 5hp.(my guess) That's plenty of hp to pull the necessary air during maximum power output

The electric fan operates at a fixed RPM. The blades are designed for maximum efficiency at the design speed. At the designed speed, the typical electric might pull 1,000cfm - 1,500cfm ( I know, some pull more ) with a 1/4hp. This is more efficient that the typical mechanical fan at this RPM, but falls short of the maximum capability of the mechanical fan(at higher RPM's).

You can see some of the issues here. At freeway speed, either fan should suffice. Under normal low-load, low speed conditions, the electic should do fine. Low-range, low speed crawling with engine RPM's up will give the mechanical fan enough speed to out do the electric. With other components in the cooling system at marginal levels, the mechanical fan would be the better choice.

The numbers I've used are just examples. It would be interesting to know the cooling requirements of the 4.0, a graph showing the cfm output of the mechanical fan at various RPMs, the ram induced cfm available from vehicle speed at various MPHs, the typical cfm/watt output of electric fans, the hp draw of the alternator at various amp loads and the percentage power loss in converting engine hp to vdc and back to electric motor hp.

One thing I do know; Jeeps roll off the assembly line with mechanical fans that only use a few hp at freeway speeds and don't overheat. A properly maintained factory design should have no problems.

 

[mbryson]

Re: Hot topic !

....................................
One thing I do know; Jeeps roll off the assembly line with mechanical fans that only use a few hp at freeway speeds and don't overheat. A properly maintained factory design should have no problems.

That pretty much sums up my feelings.........(former cooling fan experimenter......running stock stuff right now and using the engineer's knowledge instead of my assumptions--not making an @ss out of myself.....)

 

[TiRod]

Re: Hot topic !

It would be interesting to know the cooling requirements of the 4.0, a graph showing the cfm output of the mechanical fan at various RPMs, the ram induced cfm available from vehicle speed at various MPHs, the typical cfm/watt output of electric fans, the hp draw of the alternator at various amp loads and the percentage power loss in converting engine hp to vdc and back to electric motor hp.

Anybody?

Not to ignore the comment that a proper factory setup works. I can see the " if it ain't broke don't fix it " light coming on in my head.

 

[vintagespeed]

Someone must've really crapped in your Cherrios this morning. I wish it was me.

So what do you tell GM, Ford and the imports than run dual fans? They're all wrong but you're right? And you're saying that you've tested EVERY factory dual fan shroud setup out there (probably thousands) and none of them work on the XJ radiator?

.

(Post Moderated: Personal insult removed.)

LOL, I guess I was out of line with that one. Thanks big guy!

 

[Rev Den]

My wife's 2002 WJ 4.0 Auto uses the PS pump to drive the fan. How about that instead of an electric?


Rev

 

[XJJPR]

Man, go on a wheeling trip and you kids start bicering (sp?) about stupid stuff. There was even mention of something like this in Moab!

This question is the as stupid to argue about ans stick vs auto. It only has to do with what YOU like.

Two electric or clutch/electric setups WILL cool any vehicle the same as one another. You just need to set it up right to make your situation work. Size of fan and size of shroud and t-stat and so on and so on will let a system work or not work.


Now for the bicering,
ZmOz, you asked OPINIONS of others and you got some answers. If you don't agree with them then don't listen to them, but don't attack back because it doesn't agree with someone on JU. Your question can only be asnwered with an opinion because there are no facts that can answer your first question. You didn't ask for anything beyond an opinion until you tried to explain later, maybe a better worded question would have helped in the first place.



Now, my opinion, listen or not... yes I have waaaaaaay lots of experience!

160 is way to low. That XJ has to be running so rich it isn't funny. Lean that thing out with the right temp and you'll most likely gain more than 2 mile per gallon your looking for. Even in cool areas the cooling system should run at it's designed temp, XJs around 200. That is what a thermistate is designed for, stay closed until the temp rises to the correct temp then it opens and closes to maintain that temp in conjuction with the fans. You'll have to go to Siberia to get it to have a hard time to get warm.

I hate all electrical only set ups while wheeling, if the fan has enough air movement to cool the jeep right it can be waaaaaaaaaaaaaaaaaaay too noisy and can make it hard to hear spotters or drives.

So even reading the whole thread (wow!) you seem to be asking if we beleive (opinion) the stock fan pulls enough air to cool an XJ in a location labled____________ (blank) later to be Oregon will work by it's self or not?

like Eagle said (opinion) (mine too) NO!

mark
orgs mfg

 

[ZmOz]

First, please clean up your language. You came here asking for advice. It's pretty rude to insult the people who take the time and trouble to answer you.

You don't seem to understand how the XJ primary fan works. The viscous drive inherently reduces drag at higher speeds. However, the XJ fan clutch also has a thermal spring -- it's basically free wheeling until the heat rises, then the bimetallic spring locks it up to move more air. Whether or not dual electric fans will work, and remember, you asked about dual stock fans, not aftermarket units), I don't think you are going to save anywhere near 2 MPG. Probably more like 0.2 MPG.

First of all, the worst word I used was hell, get over it grandma. If you don't like it you don't have to reply.
Second, I know exactly how the mechanical fan works. I know it is suppost to, basically turn off the fan at higher speeds...guess what? It doesn't. Yeah, it slows down, yeah it puts less of a load on the engine, but the fan never completely stops spinning and even if it did that big old clutch would be right there spinning away. If you'll go back and read the thread, you'll see I asked about the stock fan, AND aftermarket fans. I can guarantee you it will save more than 0.2MPG...I don't know exactly how much it will, but even if it was just .5MPG...or even if it was .2mpg that adds up quick...especially when you're paying 2 bucks a gallon...

 

[CW]

This thread is not usefull anymore, and should die.
:skull1: :gag:

 

[XJJPR]

First of all, the worst word I used was hell, get over it grandma. If you don't like it you don't have to reply.
Second, I know exactly how the mechanical fan works. I know it is suppost to, basically turn off the fan at higher speeds...guess what? It doesn't. Yeah, it slows down, yeah it puts less of a load on the engine, but the fan never completely stops spinning and even if it did that big old clutch would be right there spinning away. If you'll go back and read the thread, you'll see I asked about the stock fan, AND aftermarket fans. I can guarantee you it will save more than 0.2MPG...I don't know exactly how much it will, but even if it was just .5MPG...or even if it was .2mpg that adds up quick...especially when you're paying 2 bucks a gallon...

Actually you used sh*t not H*ll

Not once did you mention aftermarket, just that you were looking on ebay, sounded like for stock fans.

I did just re-read everyone of your threads.

How do you know the fan isn't working properly? Did you test it while driving down the freway?

What is your guarantee that you will save more than .2 mpg? What does Eagle get if your wrong.

Now then, I'm being a dick here, just to show you your sounding like a total a$$. If you want to keep up this type of stuff here you won't find anyone to be too helpful, you might just want to keep this tone for JU. Grow up a little and play a little nicer and tone the attitude down a little.

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