After replacing with 2 bladed aluminum fan, engine noise abounds

[jquinlan]

I had a good original fan but after hearing so many people warn against them I purchased and installed a 2 blade aluminum cast fan. The instructions said that you may need to file some of the "nose" of the water pump if the cast fan rubs so I did that but just enough so it didn't rub.

After installing it, we took the model A to a couple events and the engine would occasionally develop a noisy clanging like sound. More often than not, quite noisy and sometimes barely audible.

So I removed the fan belt today and the noise went away so I was able to cite that as the source of the noise. Then I wiggled the fan and it seems like excessive play. Now I'm not sure the best way to take that play out. Here's a video of me wiggling the fan blade (pretty amateur). https://youtu.be/_V-uWNBL8vw

Any tips to help me figure this out would be appreciated.

p.s. For those stuck in the cold weather, here's a picture of our truck today at an event in Pinellas county Florida

[Synchro909]

It looks to like you didn't tighten the fan onto the taper enough. There should be a steel washer between the fan and the but that holds it on. The washer is to prevent the nut chewing up the soft aluminium fanwhen you tighten it - that's how much you have to tighten it. Depending on how long it has been loose, you may have damaged the taper in the fan. I'd try tightening it and see if I could get it to run true again.

[jquinlan]

Originally Posted by Synchro909

It looks to like you didn't tighten the fan onto the taper enough. There should be a steel washer between the fan and the but that holds it on. The washer is to prevent the nut chewing up the soft aluminium fanwhen you tighten it - that's how much you have to tighten it. Depending on how long it has been loose, you may have damaged the taper in the fan. I'd try tightening it and see if I could get it to run true again.

I just checked and there is not a steel washer between the nut and the fan. I'll find one and then try to crank it down tighter. Hopefully that will take out the play. I probably was too cautious and didn't want to overtighten it. Thanks

[ryanheacox]

There were also some repro water pump shafts that didn't have the correct taper and could cause a wobble. You said you replaced an original fan that didn't have this problem so it's probably not the shaft but it is some food for thought.

[jquinlan]

It's fixed ! Nice sounding engine again with no weird noises. I tried putting a steel washer on but then there just wasn't enough clearance to get the cotter key in. So plan B was to crank the nut down to tighten the fan as snug as possible and it worked.

The problem didn't start right away after installing the new fan blade so maybe it loosened up some after I started running it. And the nut probably should have been tightened more in the first place. I guess after breaking things over the years by over tightening I'm a bit more cautious as I get older.

I can't put into words how much I enjoy ...no, LOVE ... working on the Model 'A'. A great sense of satisfaction when you repair something. And this forum is the best resource out there. I've learned a lot reading all the helpful posts you good people have posted. Thanks again,

[ryanheacox]

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Congrats! It is a great feeling when you get things working again.

[1crosscut]

If you run across not being able to get a cotter key in again try filing a small amount off the bottom of the castle nut a little at a time.

[100IH]

Don't throw the key away and check the nut regular. Key should be in.

[Jacksonlll]

If the tapers don't match, the belt load will cause wobble and tightening the nut is not the answer. Make sure they match.

[jquinlan]

Originally Posted by Jacksonlll

If the tapers don't match, the belt load will cause wobble and tightening the nut is not the answer. Make sure they match.

Well now you got me wondering Jack. I'll take it for a longer test ride this morning and hopefully won't have any more issues. After tightening the nut, the wobble was completely gone. If it loosens again I'll buy another fan I guess.

btw Jack, I had an opportunity to pull out your book a few weeks ago "Get a Horse", on how to fix the Model A on the road. A few onlookers in the area had a good chuckle when they saw the name of the book. I'll be thinking of you Michiganders getting hit today with that "bomb cyclone" winter storm while I'm out taking my test drive

[gridleak]

if you have the wrong taper you can tighten it but it will get loose again even
with the cotter key installed. don't ask me howi know.

[jhowes]

So how do you tell if you have the wrong taper, what's the test? Jack

[Bob C]

I like to put some lapping compound on the shaft, no key installed, then lap the
fan to the shaft a little. To check the fit put a little prussian blue on the shaft
and slide the fan on then remove it and check the contact.

[lindy williams]

Bob C has the answer. Magic marker on the shaft works too. Get the tapers to match before you crack the new fan or wallow out the fan taper.

[Jacksonlll]

The belt load is offset from the bearing and puts a moment on the joint between the fan hub and shaft. Run your belt tension as low as you can. Put the fan on the shaft and try to wobble it. If it wobbles do the lapping compound trick. Must be no movement.

[Synchro909]

Originally Posted by Jacksonlll

The belt load is offset from the bearing and puts a moment on the joint between the fan hub and shaft. Run your belt tension as low as you can. Put the fan on the shaft and try to wobble it. If it wobbles do the lapping compound trick. Must be no movement.

I agree with this one completely. Many (most) people run the belt too tight. Mine is so loose, I can almost turn the belt with the motor stopped. I can easily turn the fan with only one finger, yet the alternator charges and the water pump pumps. The very design of a vee belt means that they tighten into the pulley as they drive. The more drive needed, the more they grip. Too tight only shortens the life of belt and bearings.

[Tom Wesenberg]

For sure, the belt only needs to be tight enough so the fan and generator pulleys don't slip.