Fixed Flex Fan - Complete DIY Part Number List

OldSkull · **Posted:** Tue Sep 28, 2010 12:34 pm

I have been skeptical since day one about this mod, like a body of mine here said to me "why in the hell Detroit engineers don't build the Jeep with this cheaper set up?" The anwer is "Noise" and to much cooling power! After 5000Km and the temp going down to 60F here I can now tell you there is no way I can use this fan in winter, the engine stay arround 160F and peak arround normal temp after 1hr! there is no way this setup can't work in a Canadian winter (-20F). Maybe a 1.5 inch pitch blade can do the job but not a 2.25 inch one. So yes it work and nothing is more reliable but not where snow is present in winter. I didn't use the same fan Mark use but one with similar spec I get from a speed shop in my neighborhood. I recommand you to use a front aftermarket aluminium spacer instead of rear spacer to be in the "hot spot" you need a 2" spacer, I use a 1" for testing but can add another one if need.

I have to try to modify my fan before giving up on this mod because I already drop money in it, the result can be a good and reliable setup for north cowntry owners or a adapter and spacer for sale to a Utah owners where this mod can realy shine :mrgreen:

Here my post with photo http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=54362&p=614235#p614235

Squeeto · **Posted:** Tue Sep 28, 2010 3:47 pm

OldSkull wrote:

Maybe a 1.5 inch pitch blade can do the job but not a 2.25 inch one.

You are using a similar fan to Mark's. Yours is 2.25 inch, too noisy and too cold.
It looks as if Mark had guessed (being in Alaska at the time) on the fans thickness/pitch (2.25 inch); It would be nice to know the actual thickness of the 223619.

I wonder if a 19 inch fan, being closer to the shroud than an 18 inch fan, cavitates more producing more sound.

Also some here totally remove the fan anyway. A 18 inch x 1.5 inch fan would be a compromise.

kapalczynski · **Posted:** Tue Sep 28, 2010 7:54 pm

OldSkull wrote:

I have been skeptical since day one about this mod, like a body of mine here said to me "why in the hell Detroit engineers don't build the Jeep with this cheaper set up?" The anwer is "Noise" and to much cooling power! After 5000Km and the temp going down to 60F here I can now tell you there is no way I can use this fan in winter, the engine stay arround 160F and peak arround normal temp after 1hr! there is no way this setup can't work in a Canadian winter (-20F). Maybe a 1.5 inch pitch blade can do the job but not a 2.25 inch one. So yes it work and nothing is more reliable but not where snow is present in winter. I didn't use the same fan Mark use but one with similar spec I get from a speed shop in my neighborhood. I recommand you to use a front aftermarket aluminium spacer instead of rear spacer to be in the "hot spot" you need a 2" spacer, I use a 1" for testing but can add another one if need.

I have to try to modify my fan before giving up on this mod because I already drop money in it, the result can be a good and reliable setup for north cowntry owners or a adapter and spacer for sale to a Utah owners where this mod can realy shine :mrgreen:

Here my post with photo http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=54362&p=614235#p614235

Um...please explain to me how your engine would run cooler than the thermostat opening temp??? This is simply not possible. There is no such thing as too much cooling. Noise and economy is the reason OEM manufacturers typically use fan clutches. Economy didn't seem to take a hit with this engine, probably because its such a light load on such a powerful engine. We've discussed this earlier. The fixed flex fan is half the weight of the factory setup. The only loss is because it is fully engaged instad of partially engaged all the time.

Its easy to mistake it might be overcooled, but coolant is not even circulating through the radiator until your thermostat opens. If your engine is running at 160* then your thermostat is bad because the factory opening temp of your thermostat is 176* F. I live in colorado where the winter gets in the negatives also. I consistently run between 190 to 192*F with the constant cooling of the fan.

Like I said this is because you cannot overcool a engine. If it gets colder than the thermostat opening temp, the thermostat closes until the opening temp is reached again and no coolant flows through the radiator while the thermostat is closed. Put a new thermostat in your engine and you will see good operating temps, regardless of outside air temp and air flow through the radiator.

As for noise, yes, there is a bit more noise than with a clutch, but no more noise than the factory fan with the clutch engaged.

Why change the blade pitch? The more cooling at idle where it is needed, the better. At high RPM's the FLEX fan FLEXES and the blades go nearly flat and there is very little power loss at those higher RPM's. This is why these fans were designed, they are for performance applications that NEED cooling, but do not want to lose power.

I put the fan in the shroud spaced specifically to pull more air. Too far out of the shroud and the air flow through the radiator drops significantly. If you do not want alot of air flow (I do not see why you would want good cooling) you can go with a smaller diameter fan and lose cooling efficiency and possibly gain a small economy bump over the larger fan. I mentioned earlier the factory fan WAS a 18" and I went with 19" for more cooling. A 18 and probably a 17 could be used if desired, but I would not recommend less than a 18" since that was the factory spec.

I do not use aluminum spacers because they BREAK. The diesel has an especially violent combustion cycle. I would not trust aluminum on our CRD in an aftermarket application like this. I have had a FACTORY aluminum fan clutch shaft shatter on a 4 cylinder GAS jeep and the fan cut into the radiator and sprung a leak. I was stranded instantly. I will not do this to my CRD. And again I say the same thing....I want reliability.

Good luck with your setup whatever you end up with and CRD's RULE!!! :JEEPIN:

- Mark

ATXKJ · **Posted:** Tue Sep 28, 2010 8:42 pm

Uuummmhhhh......... Kap's right

before the event of Corporate Fuel Economy standards - all vehicles had fixed fans (my 67 still does)....... I'm assuming they still drove cars in Alaska and Canada.

The main reason for fan clutches is to hit CAFE standards - same reason we have tissue paper OEM tires.

OldSkull · **Posted:** Tue Sep 28, 2010 8:43 pm

Mark my thermostat run perfectly, and the fan is 1" from the Hot spot for efficience cooling where the engineer of this Jeep have calculate the fan shoud be, not closer to the engine like yours.(this is what the fabricator of my fan suggest to do) The engine need a longuer period to get hot compare to the normal clutch fan and I'm not arguing here , I'm telling you the result I got with the part I use like it or not. I already remove 2 days ago the flex fan for futur modification and in the midtime I put back my old "Broken" clutch fan. Everything get quiet and normal now so until I find some time to modify the pitch of this fracking 2.25 pitch FF I will not recommand anyone to use the fan I use.

So please don't jump on the gun and shoot me, I have to try another way because nobody sold your FF on this side of the fence and it look like I crash and burn (For the moment) so I prefer telling the truth and wish somebody can come with the better solution for me and some fellow outside of US.

OldSkull · **Posted:** Tue Sep 28, 2010 8:53 pm

ATXKJ wrote:

Uuummmhhhh......... Kap's right

before the event of Corporate Fuel Economy standards - all vehicles had fixed fans (my 67 still does)....... I'm assuming they still drove cars in Alaska and Canada.

The main reason for fan clutches is to hit CAFE standards - same reason we have tissue paper OEM tires.

True and perfect for every gasser... and I remember we have to use a small 'Hibachi' to keep Diesel truck hot and get them start...Ho and keep the air brake on travelling because Diesel engine need to work hard to generate "Some" heat G....It was a pain in.... Now they all got electric fan....

kapalczynski · **Posted:** Tue Sep 28, 2010 8:59 pm

OldSkull wrote:

The engine need a longuer period to get hot compare to the normal clutch fan and I'm not arguing here , I'm telling you the result I got with the part I use like it or not.

I do not understand how this is possible unless your thermostat is stuck open. How do you kow your thermostat is good???

I promise I won't shoot. ha ha

Let me explain what I think is happening and why.

When the engine is cold with the factory fan:
You start it up, the thermostat should be closed, the combustion warms the engine at a specific rate, when the engine reaches 176*F the thermostat opens, then and ONLY then sould coolant be flowing through the radiator and starting to cool the engine. If the coolant is not flowing through the radiator the fan can spin as little or as much as it wants, but it will NOT cool the engine with out the cold coolant running back to the engine.

When the engine is cold with the flex fan:
You start it up, the thermostat should be closed, the combustion warms the engine at a specific rate, when the engine reaches 176*F the thermostat opens, then and ONLY then sould coolant be flowing through the radiator and starting to cool the engine. If the coolant is not flowing through the radiator the fan can spin as little or as much as it wants, but it will NOT cool the engine with out the cold coolant running back to the engine.

Now what is the difference between those two statements? Nothing except the fan. and that doesn;t change the outcome...UNLESS the thermostat is bad:

Now with a bad thermostat, if the flex fan is spinning faster than your factory fan and pulling more air through the radiator THEN your engine will take longer to warm up because the coolant is constantly being cooled BEFORE your engine is at operating temperature. This is bad and should be fixed.

That is why I think your thermostat is bad.

IF your thermostat is good (and you are positive of this) and one setup is slower to warm up, then it must have started at a colder temperature to begin with. That is the only other explanation.

I'll stay online to discuss more. Hope we can get your up and warm again.

- Mark

Squeeto · **Posted:** Tue Sep 28, 2010 10:07 pm

Mark, what about grill blocking?
This is done all the time in cold temperatures to contain more heat for the engine.

A less pitch fan would be another way.

kapalczynski · **Posted:** Tue Sep 28, 2010 11:51 pm

You bring up a good point. At some point the ambient temp could get cold enough so that when the thermostat is closed the antifreeze in the radiator is not circulating and gets REALLY cold, potentially could be close to as cold as ambient temperature if there was absolutely no circulation (of course ther will never be no circulation once operating temp is achieved, it will just be slow with the thermostat regulating the temp).

Still not sure how if the thermostat is regulating the temp and the combustion of the engine creats heat that the engine could be overcooled. The only way I can see this happening is if the convection of the air through the block itself is cooling the engine beyond the heat created. If the thermostat is closed this would be the only way to overcool right? I suppose there is also convection through the coolant from the cold radiator itself to the engine, but with the thermostat closed it would be very minimal and the heat genrated by the engine should be enough to overcome that.

If the radiators coolant is extremely cold when the engine operating temp is reached and the thermostat opens, the engine is rapidly cooled again and the thermostat closed, and the cycle repeats. But it is not like that exactly...the thermostat will never open completely, it simply would stay nearly closed to maintain the opening temp and let the cold coolant slowly flow by the barely opened thermostat. I know he is running ambient temps in the negatives up there and it definately would help to block or partially block the radiator if hes running the engine temp that low (160), but that would only help if he wasn't running a fixed fan. It probably would benefit him most in that climate to stick with the fan clutch and then block the grill so he doesn't pull air throught the radiator unless he needs it, and when he does it will engage the clutch.

If his 176 is operating at nearly closed it would average the lower operating temp.

A grill block would be a good option, so would keeping the fan clutch for him I would think.

OldSkull, what has the ambient temp been when you are maintaining the 160*F operating temps?

I know I hit in the negatives here in the winter, but usually not more than -5*F or so.

A hotter temp thermostat would help as well that way he is not opening his stat till about 190 and can maintain a warmer beginning opening temp. That really would be a big help.

Keep in mind that I have seen -20's with windchill out here in Colorado. We get some nasty winds here and fight some pretty cold temps. The only time I ran in the 160's engine temp was prior to thermostat replacement.

OldSkull keep us posted on what you try. Have you recently replaced your thermostat? How have you eliminated that from the problem?

- Mark

OldSkull · **Posted:** Wed Sep 29, 2010 3:26 am

I have done 5000Km since I install this mod last month, travelling with my 3000 pounds camping trailer and get to the city heavy traffic, nothing to worry except the excessive noise from this specific fan I bought, it’s a high performance part so maybe at the drag strip nobody care but on the street it’s another game….I just find out my truck take a eternity to get warn last week, I get to work a 6h20 in the morning , temp was around 50F under heavy rain the engine “Purring” at 1750 Rpm/ 60 Mph and the meter stay a bit low for my taste, I mention 160 but I can be 170 I didn’t dip my finger to test the temp :mrgreen:

it was not where it should be. I know my anti freeze have been done and pretty sure the thermostat was ok so I remove the FF 2 days ago and test again this time my cabin heater release hot air in the truck so does my thermostat get stock open for a week??? Nop..Do I get crap under the hood?? Don’t know yet. :SOMBRERO:

I think I will install back the FF tomorrow and record the sound of this” Monster” at 2500 rpm.

kapalczynski · **Posted:** Wed Sep 29, 2010 4:39 am

The jeep taking forever to get warm is a CLASSIC sign of the thermostat being bad.

If your temp is not up to half (or really close) your thermostat is bad. I have been in much colder climates with my fan mod and it is always at the same temp, where it should be. It usually is just barely below the half point with the factory temp thermostat in. I think your thermostat is stuck open. Would almost bet money on it.

Try this next. With your factory fan on drive straight highway around 55mph or so with no load and see if it reads low temp again. I bet it will. The air going through the radiator even with fan not engaged will bring your temp down if your thermostat is bad because it is stuck open.

Try this and let me know.

- Mark

kapalczynski · **Posted:** Thu Sep 30, 2010 5:38 am

Where is your temp sitting at Oldskull?

I drew an orange line on this pic below to show you where mine was when my thermostat failed.

[IMG thanks to GDE]

- Mark

OldSkull · **Posted:** Thu Sep 30, 2010 10:33 pm

Just get back from work with my old clutch fan installed it sit at 176F and get there in normal time no variation just stand still there and the weather indicate 57F under heavy rain outside today. This is where my gauge sit normaly (176F) from day one I bought the Jeep. I experience overheating problem this summer in heavy traffic and hot weather condition because my clutch fan was not working well. The high performance FF I use is a double plated stanless steel 10,000 rpm type so she barely flex under 4000 rpm this "sucker" is perfect for hot California weather (117F 3 days ago) or at the drag strip! I wish I can send you the FF/Adapter/Spacer to have fun with but postal charge can be a bit expensive!

No more time for testing on my side I'm busy fabricate parts for Whitfield stove service guys...

kapalczynski · **Posted:** Fri Oct 01, 2010 3:55 am

OldSkull wrote:

Just get back from work with my old clutch fan installed it sit at 176F and get there in normal time no variation just stand still there and the weather indicate 57F under heavy rain outside today. This is where my gauge sit normaly (176F) from day one I bought the Jeep. I experience overheating problem this summer in heavy traffic and hot weather condition because my clutch fan was not working well. The high performance FF I use is a double plated stanless steel 10,000 rpm type so she barely flex under 4000 rpm this "sucker" is perfect for hot California weather (117F 3 days ago) or at the drag strip! I wish I can send you the FF/Adapter/Spacer to have fun with but postal charge can be a bit expensive!

No more time for testing on my side I'm busy fabricate parts for Whitfield stove service guys...

If you are never going below the 176*F mark your thermostat is good then or at least maybe just barely starting to go out and with the extra air flow from the fan running a bit cooler. I think it is probably good to last you awhile longer though.

Not sure if you saw I posted my fan deapth. It is about 1 3/4". You said I think yours is 2 1/4"? So you ended up with ALOT of fan there. About 1/2 inch more than you need. I think your idea to trim yours is a good one. I think that is what I would recommend you start with, but be careful to mark them all evenly and cut careful so you keep the balance right. Sorry you could not find the right part number up there.

If you trim it, then let me know where your temp sits. If it is low again then it is probably on its way out.

The CRD thermostat design is a Wax pellet design and when the wax warms up it pushes on the rod and opens the thermostat. My theory is as they get older the springs pushing the other direction in the housing get weaker and weaker until the unit just opens at such a low temp that it is time to replace it.

Like I said, Squeeto has my extra factory thermostat and can ship it to you if you want to try it and see if you run warmer even with the fan. I'll let you try before you buy. ha ha. Let me know how your jeep runs after you get your fan trimmed (if thats your next step), and if it is cold again, He can send it to you. Squeeto is in Canada too, so it might be realitively cheap to ship it to you to try it.

Keep me informed, I want to help if I can.

- Mark

I hope the best for you!

- Mark

Quiksilver · **Posted:** Fri Oct 01, 2010 4:47 am

I'm in two minds about this now....

I can get the replacement Four Seasons "severe duty" fan clutch to me with shipping for $138.

Or

I can go with the FFF kit for about $180 shipped to me...

hmmm

on the one hand i know the FFF is a no worries fix, but i'm also a little cautious as to the amount of noise it makes...

How many people are using the FFF? :5SHOTS:

Now you guys have me thinking about the thermostat...my Jeep takes about 15 minutes to warm up in the mornings. Is this normal?

kapalczynski · **Posted:** Fri Oct 01, 2010 5:07 am

Not alot. This is a fairly new mod. I came up with the combo of that specific adapter and the fan. It IS noisey, but at highway speeds, even 80mph, it is not too bad. It is loudest with torque converter unlocked. Many have suggested the low profile fans to reduce noise. Might be worth a shot. I do not mind the noise at all myself. OldSkull's is about 1/2 inch thicker profile blades than the part number I used, and therefore louder. He is thinking of trimming his now.

There is a even thinner design fan than mine that could be used as well to reduce noise further.

I can go take a recording with the video camera of the sound of mine and post it on youtube for you all. It may take a day or two before I get to this, but I will get it done so you all have a reference of the noise. I'm not sure how nice the quality of sound will be, but I will try.

I do not know about you there, but at most part stores here, they will allow you to return a part if you do not use it even if it was ordered. they just ship it back for you. Great customer service. Are there any stores local to you that you can order the fan and return it if it doesn't work out? At Advanced auto here they will let me do this as long as the part still looks new.

I'm definately not trying to push this mod on anyone. I want you all to be happy and to do what works best for your rig. I just like the dependability and guarantee to run at temp, perfect, right on the nose every day. With the 192* thermostat and this fan I do just that, no matter if I am towing or running with no cargo at all my temp needle is always right at ~191*F. Even at wide open throttle, it hardly climbs one or 2 degrees and comes immediately back down to 191*F as soon as I let off the gas agan. I towed a ~6000lb dodge ram 2500 extended cab, long bed for roughly 30 miles to my house with this setup and the needle didn't move. Furthermore, I know my transmission is not going to overheat with the fan constantly cooling the transmission cooler also. No worries.

This is my temp gauge with the 192*F thermostat and FFF installed:

fnordmorph · **Posted:** Thu Oct 21, 2010 8:09 pm

115k or so miles since I bought my 05 CRD new... I hoped this mod would eliminate an overheating problem that I thought might have been caused by a bad fan clutch. The results were... interesting so far. I had my mechanic put the indicated fan and block in when he did the water pump and timing belt. I NEGLECTED to have him put in the spacing washers, but I'm not sure whether that had an effect on the result. I picked up the Liberty, and on the way home... still overheated. Must be a different problem. No big deal, wanted to do it anyhow. A few days later, my daughter gets in it to drive it around the place, and comes back in saying it won't steer. I finally get around to looking at it, and the serpentine belt is off the fan pulley. I go to fix it and find out that the fan pulley has come off its shaft. Not sure what to think about that, but its back in the shop to get that sorted out. Once I vet that problem, still have to figure out the overheating. If I can sort that out, its on to GDE stage 2 kit, i think.

fnordmorph · **Posted:** Thu Nov 11, 2010 12:24 am

Interesting result with this mod. Bought the parts, had the mechanic install them. Failed to do anything about the spacer washers. Fan seemed to work OK, but still with tendancy to overheat going uphill with A/C on in the hot. Less than 50 miles later, daughter tells me it won't steer. Serpentine belt is off, turns out the belt pulley that the fan block mounts to, which appears to be press fitted to the shaft, has come off completely (press fit failed). Had mechanic put it back together with new pulley assembly, this time WITH the spacer washers, and nothing is coming apart. Yet. Cleaned the MAF sensor while I was at it, though it didn't look too bad. Dunno if it overheats, summer is gone. Hopefully new thermostat, open exhaust, GDE stage II will make overheating problems disappear (and make it a lot more interesting to drive).

budgie · **Posted:** Sat Nov 13, 2010 8:30 am

I recently fitted the FFF kit and what a difference it has made. In the cold weather 50 Deg F everything still fine engine warming up, no problems, in hotter weather, towing about 1.5T, 90 Deg F, no issues at all, ran a little under 1/2 on the gauge.
Greatful for the great advice on how to fix a real problem.

Budgie in Australia :BANANA:

flyingdoc · **Posted:** Sat Nov 13, 2010 11:17 am

Have a look at this product is this not the answer to this viscous fan. www.kenlowe.co.uk

Fixed Flex Fan - Complete DIY Part Number List

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