[The Original] Mechanical Cooling Fan/Clutch Upgrade for 1993-1998 Jeep ZJ V8 - Page 3 - JeepForum.com
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post #31 of 53 Old 11-27-2015, 02:18 PM
zjosh93
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Originally Posted by paulsheer View Post
such a mechanical element, due to vibration, WILL slip out of alignment again. it's just a matter of time. in fact, no bolts on any part of the car prevent movement in that direction -- on the contrary, many bolts have spring washers so that when movement inevitably happens, the bolt does not loosen.
"in fact, no bolts on any part of the car prevent movement in that direction"

It isn't very clear what you are trying to say here but I'll point out for the sake of clarity that in fact almost every bolted joint loaded in shear is designed to prevent any movement of the individual members. You select a bolt size and torque such that the clamp load creates enough friction that the parts do not move relative to each other. i.e. 100% of the shear force is carried by the friction between the members. The bolt is never designed to support any shear force.

Spring washers, I must assume you mean split washers since I've never seen a wave or Belleville washer on any part of my ZJ, are there merely there to prevent the bolt from loosening and losing clamp load. If the clamp load is insufficient to prevent the parts from moving then the joint has already failed. The effectiveness of split washers is pretty debatable and most if not all critical fasteners use simple flat washers or no washer at all. For example, flywheel bolts, harmonic damper bolt, main bolts, head bolts, rod bolts, wheel hub bolts, etc.

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post #32 of 53 Old 11-27-2015, 06:13 PM
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this conversation is similar to one I had with someone who was trying to convince me that the apollo moon landing was faked.

Quote:
Originally Posted by zjosh93 View Post
...clamp load creates enough friction that the parts do not move
that's only for static loads in civil engineering

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post #33 of 53 Old 11-27-2015, 06:23 PM Thread Starter
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I am aware of the fact that the fan can slip out of alignment again over time. That might have been the case here recently. The flaw really boils down to Dorman/VDO's engineering of their fan/spacer design. I am looking into alternatives for mechanical fans. Sure, one can say "Just throw an electrical fan on there and call it a day", but this is about how the mechanical fan performance can be improved on one of these. If I wanted E-Fans, there's a 5.9 Limited at a U-Pull 5 minutes from me with its electric fan and sensors still intact.

I visited the U-Pull yard today to look into alternative fans which don't use the spacer concept, still based on the Explorer/Ranger platform. My first thought was the 9-blade metal fan on an Explorer 5.0 V8. The blades have a lot of pitch to them and appear to mean serious business (I have posted photos of one in a previous post on this thread). There were two of those up there and neither of them I could get loose. Those fans sit very far back. Due to design, the blades sit so far back they would likely make contact with the end of the A/C clutch on a 5.2. Plus, the 5.0l fan uses a different kind of fan clutch, the same that is used on a 2009-2012 Chevy Colorado 5.3l. That fan clutch is also very expensive, like $100 or so, $40 more than the fan clutch for the Explorer 4.0L.

Fitment wise, the pre-'98 4.0L V6 fans for Explorers and Rangers look to be a bolt-on type fit... no spacer required. These fans can be easily spotted by the back design, where the fan blades protrude out from the back of the fan hub. The fan, by design, sits further back on the fan clutch. This allows them to be mounted on a V8 ZJ without hitting the upper cone of the shroud under hard acceleration. I have used one of these fans in my testing... Ford FO3112107, OE to 1995-1997 Explorers with the 4.0l V6. Although the fan has 12 blades, it didn't pull as much air as the YA220. This is because the 12-blade fan has an oversized hub/body, making the blades much smaller in size, which really seems to hinder performance. That fan also didn't have very high pitch on its blades either.

Another fan I have tried is the Dorman 620-112. This fan claims it is a replacement for Explorer/Ranger fans, but it does not match the OE design of any of the OEM fans. The 620-112 is a Foxbody Mustang replacement fan, but they add in the four smaller holes and ship the spacer so that the fan can be bolted onto Explorers and Rangers. The spacer concept as Paulsheer, and now myself have found, is not a very reliable design. In addition, this fan didn't seem to cool very well. It was quieter, but the temp gauge would begin to creep up after sitting in the heat with the A/C on. Interestingly enough, I have also seen reports of Foxbody Mustangs overheating with the fan. I would say that fan is either on par, or worse than the stock 5 blade.

I am looking to acquire a 9-blade or 10-blade fan from an early 90's Explorer or Ranger (1991-1994) for testing. I saw both of them on Explorers at the U Pull yard today... Unfortunately, with the 10 blade, the Explorer's belt and some accessories were removed, and the 9-blade (accessories and belt installed) had a seized fan clutch, and it looked to had been drove like that... the fan clutch was screwed on so tight to the water pump, no matter how many times I attempted to hammer it loose, it didn't budge. Users over on the TJ forum have seemed to have good luck with them.

https://www.jeepforum.com/forum/f9/tj...06-tj-1237538/

I think the 10-blade might be a good candidate, though it may not pull as much air as the YA220 11-blade... but still better than the stock 5-blade.

Photos below are of the 12-blade fan I have tested. First photo is of the front with the fan clutch mounted. Second photo is of the rear of the fan alongside the 11-blade YA220. You can clearly see the difference in the designs.
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post #34 of 53 Old 11-27-2015, 08:37 PM
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Originally Posted by cubecompmtdx View Post
... The flaw really boils down to Dorman/VDO's engineering of their fan/spacer design.
can I suggest that you..

Quote:
Originally Posted by cubecompmtdx
chat with Dorman or VDO about it... it's their design.

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post #35 of 53 Old 11-27-2015, 09:23 PM Thread Starter
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How about we both contact them. I have planned on contacting them, though I think you would probably do the best job explaining the issues with balance as you seem to have mastered physics.

[email protected]

A buddy of mine (Who I gave the unneeded 9-blade Dorman fan to) will be giving me the old fan off of a 94 Ranger Splash so that I can see how it fits on a V8 ZJ. Will also do an airflow test to see if it pulls more than the 5MPH measured from the stock 5-blade, and hopefully close to the 7MPH measured from the YA220 11-blade. Not sure whether or not the fan is a 9-blade or 10-blade as of yet. I have also cautioned him on the balance issues, as the Dorman 620-112 fan itself seemed to have fit loosely on my Hayden 2794 fan clutch. Will probably go the the U-Pull yard and get him a different fan if the Dorman fits loosely.
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post #36 of 53 Old 11-27-2015, 09:24 PM
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Originally Posted by paulsheer View Post
that's only for static loads in civil engineering
From NASA's REQUIREMENTS FOR THREADED FASTENING SYSTEMS IN SPACEFLIGHT HARDWARE

"Threaded fasteners are often used in dynamic environments including vibration, shock, thermal cycles, and pressure cycles. As a result, threaded fasteners often experience dynamic tensile, shear, and moment loads. A properly designed preloaded joint will have sufficient preload (taking into account torque-tension uncertainty, embedment, etc.) such that the dynamic loads have little or no effect on joint integrity. However, if unexpected dynamic loads or temperature cycles are encountered that are sufficient to cause cyclic slip (localized or complete; see Pai and Hess (2002)) at the fastener thread or bearing surfaces, then fastener loosening, preload loss, and component/fastener loss can occur.

The friction at fastener thread and bearing surfaces in a properly designed preloaded joint is the mechanism that prevents slip in a preloaded joint. This friction is proportional to preload. As a result, preload is often referred to as a primary locking feature in a preloaded joint. In an effort to eliminate or reduce loosening and possible failure in the event of unexpected dynamic loads, temperature excursions or design errors; or to provide locking in fasteners without preload (e.g., fasteners in some electrical applications); additional locking mechanisms or features are often utilized or required. These include the following: (a) mechanical locking devices, such as cotter pins and safety wire; (b) prevailing torque devices such as fasteners with a deformed portion of threads or a polymer patch; (c) adhesives such as anaerobic adhesive; and (d) free spinning locking devices such as fasteners with serrated bearing surfaces or lock washers. Such devices or features are often considered secondary locking features when used in
a preloaded joint with preload providing primary locking."

Emphasis added.

As I said, just for clarity for those who may come across this post in the future.
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post #37 of 53 Old 11-27-2015, 09:40 PM Thread Starter
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I have sent Dorman an email.
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post #38 of 53 Old 11-27-2015, 11:09 PM
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Originally Posted by zjosh93 View Post
From NASA's REQUIREMENTS ... Pai and Hess (2002)
I dunno who wrote this at NASA but he is an idiot. This sort of abstruse writing is exactly what is wrong with this industry. It's impossible to work out what boundaries he is trying to set. It's like an exegesis from the Vatican. Perhaps it's just out of context - ?

From Pai and Hess (2002)

"Previous experimental work has revealed that fastener loosening occurs as a result of complete or localized slip at the thread and head contact surfaces. ... The results show that loosening can occur at relatively low shear loads due to the process of localized slip."

Hay :-) that's exactly what I said! :-)

NASA is kinda sortof saying that you should show in your calculations that you have taken into account all known factors but that there may be factors you can't account for like "unexpected dynamic loads, temperature excursions" in which case you can still get creep/slip, in which case you should also use locks.

This lines up quite well with what happens in aviation practice: many bolts are tied down with a WIRE that goes through the corner of the bolt. They must KNOW these suckers come loose.

Engine building manuals often say to use locktite on flywheel, torque converter, main-pulley bolts. They must know these things come loose also. This can only be because the mating surfaces are creeping IMO.

The temperature aspect I didn't think of -- it's yet another reason why you get mating surfaces creeping in spite of bolt preload.


Basically, if you have a vibrating, spinning, reciprocating element, and you want two things to stay exactly aligned, then you cannot rely on a flat mated surface not slipping.

It WILL slip.

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post #39 of 53 Old 11-27-2015, 11:26 PM
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Quote:
Originally Posted by cubecompmtdx View Post
How about we both contact them.
you are going to contact Dorman about a Ford fan you are using on a Jeep?

seriously Nick?

Oh pleeeease can you record that support call. I want to submit it to SNL.

Nick, do you realize it has taken you 14 WEEKS to work out that this spacer is bad for your water pump bearing since Taz360ZJ suggested as much in my original thread?

Don't you think "someone" besides Dorman is at fault here?

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post #40 of 53 Old 11-28-2015, 12:16 AM Thread Starter
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In the email, I actually mentioned nothing about the fan being mounted to a 1996 Jeep Grand Cherokee... I referred to the applications the 620-112 fan and spacer are meant to fit... Explorers, Rangers, and Mustangs. I did email them a long time ago asking if they could source the spacer as a standalone item.

Regardless of whether the fan assembly is mounted to a Jeep's water pump or a Ford's, the same issue is still present. The fan setup does use a fan clutch specced to fit a Ford Explorer, not a ZJ. That being said, this issue would be present on Ford vehicles as well, when the fan and spacer are being used on the vehicles it is specced to fit. Dorman's design is at fault here... No I did not catch onto the flaw right away... I have to see things visually. Others on the TJ forum had been using the Dorman 620-112 spacer and fan on their 2000+ TJs long before I had started my own project with the ZJ V8. The balanicing issue is actually more apparent with the 620-112 fan vs the YA220 OE Ford fan... and that is because the center hole and bolt holes on the 620-112 aftermarket fan are oversized.

Taz360ZJ's post on your thread "you can kiss your water pump bearings good bye" never really implied as to what or why. Nowhere in his post did I see anything regarding the flawed design of the spacer. Honestly, his statement told me nothing about the flawed design of the spacer.

Here's a copy of the email I sent to Dorman...

Hello,

I would like to voice my concerns regarding the Dorman 620-112 fan blade and its supplied spacer. When the fan is used for a Ford Explorer or Ranger, the fan blade itself has some back and forth play when mounted directly to the fan clutch, but not tightened down. The fan clutch has a circle shaped piece of metal, which the hole on the center of the fan is supposed to have a tight fit around... this ensures that the fan doesn't get mounted off-balance, or that the fan doesn't drift off balance over time with use due to centrifugal force. I have used two Dorman 620-112 fans and both would get off balance as there was a gap between the hole on the back of the fan and the raised circle on the fan clutch.

Here's the second problem with the design... Shipped with the fan blade is a ring shaped spacer. This allows the fan to be spaced back roughly 1.5cm or so from the fan clutch... to mimic the OE fans on early 90s Explorer and Rangers. While the spacer has a tight fit around the raised circle on the fan clutch, the fan blade can easily be mounted off-balance or can drift out of balance for the same reason as mentioned before... centrifugal force. Except with the use of the spacer, there's no center raised circle for the fan blade's hole to fit snugly around. This lack of a balancing lip on the spacer guarantees that the fan blade will drift out of balance over time. When the fan drifts out of balance like that, it will cause accelerated wear on the fan clutch and water pump bearings. In the case of a fan that gets brittle, it can cause the blades to fly off, causing serious damage to the radiator, hoses, belt, hood and other places in the engine compartment. There are two things this fan and spacer need to have done to alleviate this problem...

1. On one end of the spacer, add a raised balancing lip, which protrudes up on one side to allow the fan blade something for it's center hole to sit tightly around, so that the fan will be properly balanced

2. On the fan blade itself, the center hole should be machined to where it has a diameter of 64mm. If the Mustang application requires the slightly higher diameter this fan has, then the the mustang replacement fan should be sold under a different model, and the Explorer/Ranger application a different model as well.

If you have any questions, feel free to ask.

Regards,
Nick
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post #41 of 53 Old 11-28-2015, 01:55 PM
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Originally Posted by cubecompmtdx View Post
Taz360ZJ's post on your thread "you can kiss your water pump bearings good bye" never really implied as to what or why.

no, i think everyone got the what and why -- i certainly did, otherwise i would have ASKED.

there are people that 1. can't grasp simple things 2. refuse to accept reality 3. refuse patient explanations 4. are suspicious of criticism 5. mess things up 6. are ungrateful when others save them from their own errors 7. but instead go looking around for someone to blame.

any one of these is deficiencies is forgivable, but the world just doesn't need people that have the combination of ALL 7 elements

do you see what I'm saying?

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post #42 of 53 Old 11-28-2015, 07:14 PM Thread Starter
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Yeah, I see what you're saying, but the design is at fault of Dorman... it just took me awhile to see the flaw myself. There... I admitted it again. Now, if I had come up with the design myself, then yes, I would take the full blame. I did use an OE Ford fan vs the actual Dorman 620-112 fan blade, but the same design flaw... in regards to the spacer not having any sort of centering lip, is present on whichever fan one would choose to use with that spacer. I did run the Dorman fan for a couple of days but removed it as it didn't cool well.

I have picked up another fan to try... It's the 10-blade fan from a 1993 Explorer. It's got some stress on it, but feels sturdy and intact. As it is winter, I won't be able to assess cooling performance right away, though I can measure the idle airflow with the fan clutch engaged to get an idea on how well it will perform. As it is 22 years old, I will replace it with a brand new one if this one seems to work well.

In addition, I pulled the metal fan off of a 5.0 Explorer and it does not fit well at all. The back of the blades nearly touch the A/C clutch and crankshaft pulleys. Too close for comfort.

Mounted both fans to a 5.9 limited to see how they look. The 10-blade looks like it should fit fine... NO spacer needed.

Test Vehicle (mounting)


The fan seems to have a decent amount of clearance from the accessories, roughly the same as the 12-blade fan, and the spacer mounted YA220




V8 Explorer metal 9-blade mounted... way too close to the accessories... only clears the A/C clutch by a few millimeters




Here you can see literally how close that blade is to the compressor clutch


Stock 5-blade on a 5.2 nearby. You can tell that the V8 ZJ's cooling system is built to where it is just enough, with 18PSI of insurance when the temps creep over 230. The Explorer V8 looks to have a more capable cooling system. That monster of a fan should speak for itself.


Meanwhile, here's a photo of the 10 blade fan after pulling the clutch off... Paid $3 for it and brought it home.


For those curious, here's what a OEM 9-blade Explorer fan looks like... Much beefier than the Dorman 620-112 9-blade fan. Ford used this for the 1991 and 1992 model years and I believe they fully switched to the 10-blade for 1993-94 years. In one photo, I am holding the 10-blade above for comparison...



If the images aren't showing, let me know. It's been awhile since I have hosted images from Photobucket.

Last edited by cubecompmtdx; 11-28-2015 at 07:16 PM. Reason: Photo fixes
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post #43 of 53 Old 11-29-2015, 02:19 PM Thread Starter
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Another update... lots of photos!

Here are some photos I have shot of the 10-blade along with the Explorer 12-blade and stock 5-blade, dogs included...

Explorer 10 blade, Explorer 12-blade and stock 5-blade


Closer look at the 10-blade and stock 5-blade


Closer look at the 12-blade and stock 5-blade


Sideways look at the 10-blade and stock 5-blade


The blades on the 10-blade have roughly 2/3 the amount of pitch of the blades on the stock 5-blade... but the 10-blade has more blades to work with.


Installed the 10 blade today... Before I mounted it, I cleaned it up as good as I could... got all the buildup from around the inside of the center body. It was nasty. The fan seems to mount well within the shroud. When mounting the Explorer fans, it's important to have more gap between the blades and the shroud in the upper passenger side corner, so that when the engine pulls toward that direction under jackrabbit starts, the fan won't make contact with the shroud. The ZJ should does have some up/down adjustment available. Make sure the shroud is raised up as high as possible on that side, though also making sure there's a small gap on the bottom. Fan does seem to perform well. Noise is about the same as the YA220 11-blade, though it pulls slightly less air. The 10 blade still gives 1-1.5MPH more flow at the grille vs the stock 5-blade. These measurements are performed with the engine at a warm idle in Park. Here's a roundup of what each of the fans I have tried seem to do... I never measured the Dorman 620-112 9-blade.
  • Stock 5-blade - 5.1MPH
  • 1995-97 Explorer 12-blade - 5.4MPH
  • 1993-94 Explorer 10-blade - 6.3MPH
  • 1998-2001 Explorer (YA220) 11-blade - 6.7MPH*

*Average from two separate measurements

Here's some photos of the 10-blade mounted...

First let's take a look at the shroud spacing on the upper passenger corner. Those scrape marks in the shroud are the result of running the YA220 without the spacer. This is why we have to use a fan that is recessed back from the fan clutch a little ways.


Here are some additional photos of the fan mounted...






Here you can clearly see the recessed design of the blades on this fan. The blades stick out from behind the center hub. The fan clutch sticks out a good bit, as can be seen in prior photos. When the YA220 fan is mounted directly to the fan clutch, the fan body completely covers the sides of the fan clutch.



Another advantage this style fan gives is better accessibility. It is much easier to get a wrench in there. Also, you can see how this fan is mounted properly against the fan clutch... no spacer needed here. Ordering a new 10-blade fan is definitely on my to-do-list. A seller on eBay has Depo replacements for $25 w/free shipping. My uncle who works at Precision Tune commented on the cracks in the fan... he says he sees them come in like that all the time with cracks, but has yet to see one come apart. He says he does sell a bunch of replacements though. Now that I have evaluated this fan's fitment and airflow, I will be getting a replacement asap.

Last, but not least, a photo of the anemometer...
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post #44 of 53 Old 11-30-2015, 12:44 PM Thread Starter
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Took the Jeep for a drive with the 10-blade fan installed. This fan is slightly more audible than the YA220 11-blade when engaged. During this time of the year, the fan for the most part, only is engaged at cold startups. I believe the slight increase in fan noise can be attributed to the fan's aggressive pitch on the blades. The pitch height is roughly the same as the YA220, but the slope is more aggressive.

Meanwhile, Dorman has replied back to me... they stated that "they have had this design for a while, yet not noticed any issues with failures, but would forward my concerns to their products dept for product improvements".

Here's a copy of the email...

"Nick,
Thank you for bringing this to our attention. We have been using this design for quite a while without any issues. I will forward your email onto the product group as a suggestion for product improvement. Once again, thank you for your suggestions"

I'll take the "We have been using this design for quite a while without any issues" statement with a grain of salt. I imagine there may have been water pump failures due to the fan, but Dorman probably never heard of such failures. Also... I had ordered a Dorman 902-318 water outlet to replace my defective leaking one... the Dorman unit was so flawed in design, it was guaranteed to leak. Didn't match the OEM design on the mating surface at all, plus the water neck was angled 90 degrees, not slanted like the OEM. At least the gasket looks like the OEM one, though I'm sure they sourced the gasket from somewhere else. Instead of using the Dorman unit, I went to the U-Pull and grabbed an OEM outlet from a niner. Works great. Amazon refunded me without me having to return the crappy Dorman unit.
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post #45 of 53 Old 01-09-2016, 10:34 PM Thread Starter
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Time to update this thread for the new year. Back in the beginning of December, I ordered a new 10-blade fan from eBay. It's an aftermarket replacement made by DEPO (an odd name). The first one arrived defective with a chunk of plastic missing from one of the blades. The seller quickly sent a second one and I got to keep the first. The second arrived fine. Got it installed a couple days later. It's been on there for over a month. Unlike the Dorman 620-112 that many parts houses and sellers claim to be an OE fit, this fan is an OE fit for 1993-94 Explorers and 4.0L Rangers with the "super cooling" package. Many have used this fan on their 4.0L TJs with good results, and airflow-wise, it does better than the stock 5-blade and the Explorer 12-blade (which itself didn't allow temps to get over 220 sitting in traffic in 100F temps). The new fan seems to fit well, with a good amount of space between the blade tips and upper passenger side of the shroud. I have punched it hard enough to spin the tires (2WD) and not have any problems with the fan hitting the shroud (like I did with the YA220 without the spacer). It is important though to make sure your motor mounts are in good condition. The plastic on the 11-blade YA220 has a lot of flex to it and is more forgiving to shroud contact, whereas the older style 10-blade is stiffer, and would likely get damaged (or cause damage) if it makes hard contact with the shroud. The DEPO fan does not have much flex in its plastic, and being a Taiwanese made product, the machining of the plastic isn't 100% perfect, but to be expected of a $25 fan blade. The aftermarket fans have been rumored to have more significant cracking issues, even when they are still relatively new. Mine has not shown any signs of cracks or stress so far. I'd assume the harsh temperature swings experienced in winter would really put this to the test... heat from the hot radiator, vs sitting cold in ~20F temps. I have attached some images of the new fan installed to the fan clutch and mounted.

Now regarding the email sent to Dorman about their 620-112 fan blade... As I figured, I have not heard back from them since their original reply. The balancing issue myself and Paulsheer experienced when using Dorman's spacer to mount the YA220 fan... also applies when mounting the actual 9-blade fan shipped with said spacer. I did mount that fan for testing last summer, and it didn't really seem to cool any better than the 5-blade. I don't have airflow tests as I didn't have the anemometer at the time. The process of threading it onto my ZJ would be no different than an Explorer or Ranger. What Dorman and VDO have done here is instead of manufacturing direct replacement 9/10 blade Explorer fans, they have taken the OEM design of a Foxbody Mustang 9-blade fan, tap 4 smaller size holes in it, ship a ring spacer, and call it an OE equivalent replacement, when it's not... both fitment wise and cooling wise. The actual 9-blade used on 1991-92 Explorers has different blade dimensions and does not use a spacer. This is why the 620-112 fan has 8 holes around the center - the larger holes are for the Mustang, and the smaller holes for the Explorer. The spacer allows the fan to sit back like the 1991-1997 Explorer fans do. The only vehicle this fan should be marketed as a direct fit is the Mustang.
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