Oem 7-blade Dauntless Fan

The OEM 7-blade cooling fans that were an option on the 225 V6 are very difficult, and maybe nearly impossible, to find these days. I wanted to let those interested know that I found another source for these fans....sort of.

(Note added Aug. '23 - As another alternative, there's a source for 7-blade fans of a different type noted below in post #17 of this thread).

The 7-blade fan I recently found on eBay was from a 1972 Jeep Cherokee with the 258 straight six. Evidently, on the '72 (and maybe later?) AMC 258, Jeep kept using the same basic 7-blade fan design that had been available on the later model 225 V6s as a heavy-duty cooling option, paired with a 3-row radiator. The 7-blade fan may have been optional on the 258 (vs. standard) as well.

Below is a photo of Rubicloak's OEM 7-blade Dauntless fan (thanks, Eric!) at left, next to one of the 258 fan at right. For the purpose of comparison, I've rotated these images so that the unevenly spaced blades are in approximately the same orientation in each photo.



Both the 225 and 258 7-blade fans are 15-1/2" +/- in diameter, and have identical blades with the same asymmetric spacing. Both are stamped on the front with a capital H, indicating they were made by the same manufacturer (Hayes-Albion, which also made fans for GM and others). As far as I can tell, the only difference between these two fans is that the bolt circle on the fan used on the 258 was about 1/8" larger than that on the 225 fan.

After getting the fan from the 258 blasted, in an effort to adjust the bolt circle dimension to work with a Dauntless, I tried slotting the bolt holes using a die grinder. This proved to be an exercise in futility, as the steel is just too thick/hard. The idea of drilling new holes at a 45 degree angle to the original pattern also occurred to me.

Fortunately, a friend offered a better solution, and used his milling machine to "correct" the minor difference in the bolt hole spacing. The formerly round bolt holes are now each slightly slotted (about 1/16") toward the center of the fan.



The original 7-blade fan for the 225 was used with a 9/16" wide spacer. I wasn't able to find a spacer in that exact width with the 1-3/4" bolt circle needed to fit the 225 water pump, but did find a 1/2" spacer with the correct bolt pattern, and it appears that one will work ( https://www.ebay.com/itm/333238320770 ). However, I'd like to find an OEM Dauntless fan spacer if I can.



Here's the modified fan with the spacer bolted to a spare 225 water pump. The lock washers completely cover the newly slotted mounting holes.

 

Thanks for sharing.
I ended up with one of those fans and was not about to modify it for reasons defined above. I used a 6-blade flex fan instead.
It's now a piece of decor in our family room...per my wife's suggestion!
And, no, she won't sell it.

 

Great write up and pictures Maury! You always have very detailed posts which are greatly appreciated! Love your attention to detail.

 

Great info! Thanks Maury!

 

I finally got around to installing the 7 blade fan over the weekend, including an OEM spacer (thank you again for your help finding these parts, Rubicloak and Oldtime!)


After removing the original 5 blade fan, I was surprised to see that though the pitch of the blades is similar to that on the 7 blade fan, there's a big difference in the area of the individual blades.



The area of the blades on the OEM 5-blade fan is approx. 14.6 sq. in. per blade x 5, for a total blade area of 73 sq. in. +/-

By comparison, the 7 blade fan has about 80% more total area, with approx. 18.9 sq. in. per blade x 7, for a combined blade area of 132 sq. in. +/-

The 7 blade fan moves a LOT of air. It will hold a piece of cardboard against the grille at idle. The increase in air flow when the engine is revved is audible. On the downside, it no doubt saps more horsepower than the 4 or 5 blade fans do.

The Dauntless definitely runs somewhat cooler with the 7 blade fan, as the temp gauge needle now stays closer to “C” than it did with the 5 blade - but I don’t know what that translates to in terms of degrees.

 

Are there any part numbers stamped on fan? Thanks...

 

Just out of curiosity...did you have cooling problems before? What is the diameter of the fan and did the wider radiator use a larger
diameter fan blade?

 

I've always been curious as to why the blade was spacing was not the same.

 

My engine didn't have any significant cooling problems before, though it's internally modified quite a bit, and did tend to run slightly on the warm side. I already had a 3-row radiator, and I was looking for one of these fans mainly because I just liked the idea of getting the additional air flow through it.

AFAIK, the wider radiators went into production with the 1970 models, which I believe is also when the 7-blade fans became available as a heavy-duty cooling option on the Dauntless. The 7-blade fans are the same diameter as the 5-blade version - about 15-1/2" - so they will fit inside any of the OEM Dauntless radiator shrouds. A 4-blade fan was standard on the V6 during some model years, and I'd guess they were likewise that same diameter.

 

Yeah I wondered that too - but after researching it a bit, the answer was not what I'd expected. I'd thought it had something to do with air flow - and in a sense it did, but only indirectly.

The reason I was able to find as to why the radiator fans were made with asymmetrical blade arrangements was (apparently) because the uneven blade spacing helps to reduce noise. That said, if anyone else has any other knowledge or opinions on that subject, I'd be very interested to hear from them.

 

The only marking on the fan I found is the "H" mentioned above.

However, unlike mine, Rubicloak's is an original Dauntless fan, and it may have some numerical markings along with the H. Maybe he'll chime in here and tell us....

 

My original paint early '69 (flat top/bottom wiper windshield and no side markers) has the wide radiator in it.. ... with the 4 bladed fan. It had no shroud when I got it but I added one. My '68 has the narrow radiator with the original shroud and a four bladed fan. It seems like '69 was the switch to the wide radiator.

It's for noise reduction. The uneven spacing helps prevent resonance. You can see that on your tires too. If you rotate them around, the basic tread pattern shape is the same, but the size of the blocks in the front-to-back direction will vary.

 

Thanks for the clarification on that. Do you happen to know if the 7-blade fan was available as an option on the ‘69 models?

 

That I do not know.

 

I asked him about it, and Rubicloak’s OEM Dauntless 7-blade fan is likewise only marked with an H.

 

Though there weren't any numbers stamped on the 7 blade fans, the following page from the March 1971 Parts Book shows the part numbers for the 7, 5, and 4 blade fans for the Dauntless (highlighted):

I also checked my Sept. 1966 Parts Book, and along with the 5 blade fan for the V6, I was surprised to find the 7 blade fan also listed (below) - so it turns out these fans were available as early as the 1967 model year, and possibly before.

If anyone has a Parts Book from the 1966 model year, it would be interesting to know whether or not it lists the 7 blade fan.

Note that the part number shown below for the 7 blade fan (942015) has two of the digits reversed from the one in the '71 Parts Book above (924015). Based on the part numbers of the other fans, I'd guess the earlier version is the correct one.

 

If you're looking for a 7-blade fan for a Dauntless, and aren't concerned about originality, here's another option that might work for you.

The OEM 7-blade fan produced for the late AMC and early Mopar 4.2L / 258 c.i. straight six, Jeep part number J5357390, was evidently optional as part of a heavy-duty cooling system package for that motor on certain models:

https://www.factorychryslerparts.co...Drive-Without-Fan-Drive/4512663/J5357390.html

This fan has the same 15.5" diameter as the OEM fans for the 225, so it will fit inside the Dauntless radiator shroud.






However, like the earlier 7-blade fan for the 258 discussed in the initial post, the mounting bolt circle on this fan is slightly larger than that on the 225. In order to mount it on the Dauntless water pump, the 4 bolt holes each need to be slotted (ideally using a milling machine) about 1/16" toward the center of the fan. Any machine shop should be able to make this adjustment. Alternatively, with the right equipment, a new set of holes could be drilled to match the 225's mounting bolt pattern. Just keep in mind that the tempered steel used on fans is very hard.

Also, a fan spacer of the appropriate thickness (possibly 1/2" or 3/4"?) would likely need to be used.

According to the info in the link above, J5357390 superceded the earlier Jeep part number J0998795, which was likely also a 7-blade fan with the same diameter.

In case anyone's interested, the two J5357390 fans shown above are both currently listed on eBay (in Aug. ‘23):

https://www.ebay.com/itm/265672521577

https://www.ebay.com/itm/175868243510

 

Thank you, Maury.