Fan Keeps loosening on water pump
 

Hi all:
I have a question about my 4 blade, stamp metal, riveted fan loosening up on a new stainless water pump shaft. My fan was sound, and has been on the car since restoration in the 50's, I rebuilt the water pump last year and installed a new stainless shaft from Brattons or Snyders, (I haven't looked for my invoice) and now the fan has loosened up a couple of times. I've been able to get the cotter out to tighten the nut which cures it for a few hundred miles, and this last time, it wasn't very loose - I just barely tighten it one notch. So it seems to be getting better, or tighter.

Should I just bite the bullet and take the rad off and see what's going on? Or could this be getting the key re-seated, or something? Are the shafts known to be off in the taper in some shafts?

Just looking for input.
Thanks,
Roy

Re: Fan Keeps loosening on water pump
 

Any time the shaft or fan is changed, it's best to trial fit the two together without the key, just to be sure the taper is a perfect match. Then use the key and make sure the fan hub still fully seats on the shaft taper.

If the fan hub is aluminum it's best to use a thin steel flat washer under the nut.

If the taper is a slight mismatch, I've heard of guys using valve grinding compound to lap them together.

Re: Fan Keeps loosening on water pump
 

NOT RECOMMENDING THIS, but I put BLUE LOCTITE on the taper, NEVER came loose, BUT, when I had to remove it, later, it wuz a BITCH to get OFF!!!
Bill W.

Re: Fan Keeps loosening on water pump
 

I like to put a little lapping compound on them and then
check the fit with Prussian blue.

Bob

Re: Fan Keeps loosening on water pump
 

Look very carefully at the fan hub, has it cracked? I had one year or two ago that cracked and kept coming loose. I put a different fan on, threw the cracked one away, and problem solved.

Re: Fan Keeps loosening on water pump
 

Thanks for the suggestions guys.

WOody 31 - I must admit I didn't look the hub over for cracks when rebuilding. The hub is steel, and was well used veteran, so I didn't think of it.

Everything tightened up ok on the bench, but I'm wishing now that I had checked the fit with blueing.

Roy

Re: Fan Keeps loosening on water pump
 

Years ago I wrote a short paper on this joint. I can't find a copy, but it is in one of my books and you can see it at this site. It is a preview and you don't have to buy the book to read it. This subject is on page 28 and I hope this site will bring it up for you.
http://www.blurb.com/books/2102520-m...tips-and-hints

If not, go to blurb.com, search for "Model A Tips and hints", go to the preview, find pg. 28 and enlarge it so you can read it.

Re: Fan Keeps loosening on water pump
 

Thanks Jack, your link worked.

I have bumped into your tips book before, and appreciate your suggestions on this and other subjects.
Roy