OT: Finding a mechanical engine fan by dimensions

Does anybody know of way to search for a radiator fan by mechanical dimesions? Email to Dorman was replied to with a stern "no".

The water pump on my '72 Scout started to leak. Since the OEM fan clutch is unfindable I decided to go with a pump that uses a bolt- on clutch, but the clutch I ended up with has a larger bolt circle and centering boss than the OEM fan.

The clutch I'd like to use has a four on 3 1/4" bolt pattern with a 2 5/8" centering boss. The fan shroud is 19 1/4" ID, water pump rotation is clockwise looking at the front of the engine.

Apologies for bending the "metalworking" concept, but Scouts are mostly metal and I think I'm looking for metal fan 8-)

Thanks for reading,

bob prohaska

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Or a metal fan adapter plate?

<snip>

Did you try Rockauto? Maybe:

Then I'd still have to find a fan. The OEM fan won't fit over the mounting flange of the new clutch and has a too-small bolt circle.

Thanks for writing,

bob prohaska

That looks broadly like the clutch I got with the new water pump. But, no dimensions or even a good description.

If there's a way to search parts by category and description please point it out, I couldn't find it.

Thanks for writing,

bob prohaska

I decided to order a fan from Amazon, based on a few words on the manufacturer's website:

Flange bolt circle: 3" / 3 1/4" Flange diameter: 2 3/8" / 2 5/8"

After long reflection it crossed my mind that what they called "flange diameter" might be the centering boss diameter. I'll find out in a week.

Thanks for everybody's patience!

bob prohaska

If you have machine tools it should be quite easy to fabricate an adapter plate . It doesn't have to be something as skinny as a piece of

1/4" plate ...

Hopefully this works out for you🙂

Many years ago I installed a "Flex-Fan" on a big block that was having problems cooling during the summer. It was just a simple order from Sears back then...

They are still around it seems and maybe they have one that might fit:

They have a more universal fit than OEM. They work differently too. At low speeds they scoop a lot more air. As the motor revs up the blades collapse (flex) becoming more efficient.

An adapter between the clutch BC and the fan BC? Unfortunately the mounting flange of the clutch is too big to fit through the center hole of the OEM fan. Apart from that little niggle the idea would work. It would definitely work in a case where the fan was larger than the clutch.

Thanks for writing!

bob prohaska

I thought about a flex fan, but it would require yet more hardware to reach the fan shroud. The fan from Amazon comes to $60, if it fits, problem solved. If it does not fit maybe I'll reconsider...

Thanks for writing,

bob prohaska

<snip>

On that same old big block with cooling woes... I tried a "fan clutch eliminator" too. It was an adapter with lots of bolts🙄 that took the place of the fan clutch. This took care of the spacing to shroud problem. Search that has some results for this both pro and con:

Pretty sure it's still around somewhere in my stuff along with a couple fan clutches and likely the original fan blade too...

An adapter between the clutch BC and the fan BC? Unfortunately the mounting flange of the clutch is too big to fit through the center hole of the OEM fan. Apart from that little niggle the idea would work. It would definitely work in a case where the fan was larger than the clutch.

Thanks for writing!

bob prohaska

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If you can get a spare OEM or similar fan perhaps you could open up the center hole and drill new bolt holes.

I was visualizing a puck with the correct features for the water pump on the back and the correct features for the fan/clutch on the front . Maybe an inch thick , maybe a bit more ... unless that puts too close to the radiator .

I'd prefer to use a clutch if possible. The Scout's gas mileage is bad enough already, I'd rather not make it worse 8-) But, if the blade I ordered won't fit, and the blade I have won't fit, I might opt for a clutch eliminator as a temporary fix.

One small discovery so far is that 3/32" teflon cord valve bonnet packing seems to make a good water pump gasket. The paper gasket wouldn't seal owing to warpage between pump and housing.

Thanks for writing!

bob prohaska

The clutch fits the water pump correctly. The fan needs to fit _over_ the clutch mounting hub and mounts to the back surface of the clutch body.

Unfortunately the center hole on the fan is too small to fit over the clutch hub and the fan bolt circle is too small to fit the clutch. Here are a few images, hopefully they'll clarify the topological problem:

The obvious way to use the fan and clutch that I have together would be to bore out the ID of the fan and re-drill the bolt circle. That wouldn't be impossible if I had an 18" swing lathe. I have only a 10" (maybe 11" over bed) lathe, but taking the fan apart, doing the machine work and riveting it back together is a lot of work and not easy to get right.

At this point all fingers (and other appendages!) are crossed in hopes the fan on order will fit the clutch on-hand.

Thanks for writing,

bob prohaska .

OK , if I understand correctly the 4 slot flange bolts to the pump and the fan bolts to a surface that is hidden by the fan . Got a mill and a boring head ? Is the current fan's base circle diameter big enough to drill the bolt pattern of the new clutch ? I could adapt that fan to that clutch in my shop .

OK , if I understand correctly the 4 slot flange bolts to the pump and the fan bolts to a surface that is hidden by the fan . Got a mill and a boring head ? Is the current fan's base circle diameter big enough to drill the bolt pattern of the new clutch ? I could adapt that fan to that clutch in my shop . Snag

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Two notches in the fan hole might get it over the flange without losing centering. Does the clutch body size allow you to tilt the fan and slip an edge of the hole into one of the slots to gain clearance?

Perhaps you could make an adapter disk on the lathe large enough to attach to the fan with the proper center and mounting holes and rough out the fan hole to a scribed line with hand-held tools, as I have to do to mount a round meter in a panel too large for the mill. Also make a 1 or 2 piece stepped plug to center the fan on the adapter plate and drill the matching hole pattern before opening up the hole.

I think the answer is "yes", but the clutch centering boss is 2 5/8", while the fan bore is 2 3/8". There's enough metal on the clutch to turn down the centering boss to 2 3/8", if that runs true enough a new bolt circle on the fan can be made with hand tools. If the new fan arriving today won't fit it might be worth a try since the clutch will fit in my lathe.

Thanks for everyone's help!

bob prohaska

No idea what the clutch fits??

Which engine do you have? most 1972 Scouts used AMC engines - 194, 232 or 258 inch sixes and most 304 V8s were AMC - so AMC clutches and fans dhould likely fit????