18" vs 18.5" - 7 blade fan

[Playtimefun]

Good day folks... I need some techical advice on fan blade sizing.

Unfortunately, the water pump shaft snapped on my 340 and my 7 blade 18.5" fan (with clutch) went half way through my rad. I have been trying another 18.5" blade but am continually finding 18" ones. Now I am running a 22" rad without a shroud. I have never had overheating problems before and I drive it pretty hard.

Being that the open area on the rad height wise is 16" and width wise is 22", do I need to try and find the 18.5" versus the 18"?

An old timer told me that because my rad opening is smaller (height wise) then the fan, that the extra width won't make a difference. Since I am having a tough time finding an 18.5" fan (everybody is backorder etc) maybe its not a big deal?

Thoughts?

View attachment 20250816_124354.jpg

View attachment 20250816_141036.jpg

 

[pschlosser]

bummer. I feel your pain. I too, lost a water pump shaft going "over the grapevine" in California. The grapevine is a major interstate that climbs 4144 ft and down again, and not an uncommon place for cars to break down.

While my fan blades were a little bent, and the radiator beyond repair, after bending the blades back in place, I discovered the fan was still in balance. So, it may be possible to "save" you fan setup, saving you from replacing it.

That said, my car is still pretty darn stock, so when replacing a part, I may throw on what I have on hand, but if it's not the "correct part" I may continue to be on the lookout for one, checking epay and swap meets whenever I can.

An 18-inch fan, if that's all you can find, will work just fine.

 

[heminut]

An 18-inch fan, if that's all you can find, will work just fine.

Yup, what he said!

 

[Playtimefun]

Yeah... unfortunately trying to bend and straighten it out... just ain't in the cards lol. I'll have to post a picture of the fan itself lol.

 

[pschlosser]

Yeah... unfortunately trying to bend and straighten it out... just ain't in the cards lol. I'll have to post a picture of the fan itself lol.

my fins were only slightly tweaked, with no missing material, and once straightened (not perfectly, I admit) still seems to be in balance when spun. I've since put 100K miles on it, over the years, the the water pump is still going strong.

 

[Playtimefun]

I found this... but i dont have the year for it, but it is interesting!!!

 

[pschlosser]

I found this... but i dont have the year for it, but it is interesting!!!View attachment 144555

that image will be from the 1970 Plymouth Service Manual.