Broken fan hub
 

So I was heading into work and the engine started making the gawd awful banging and rattling, so I cut through 3 lanes of traffic to get to the curb, get out and lift the hood and find the center of the hub on my 4 blade fan has split in two and is about a millimeter from coming off and going through my radiator.

So what would have caused this to happen? I have already ordered the aluminum 2 blade style from Mac's, is there anything special I need to know to install the new 1 piece aluminum fan?

-Eli

Re: Broken fan hub
 

Old age, metal fatigue, old age................ I doubt if fan belt tension on the A could do it, but if it's an "old" V8 fan who knows? JMO
Paul in CT

Re: Broken fan hub
 

All old fans need to be looked at and are subject to failure. They are old.Working on equipment and trucks I have seen lots of fan failures over the last 35 years.I have had good luck with the old four blade types,as long as they were not rusty,or bent from people turning them over by hand,then bent back again.The only fan failure I had on an A was an aluminum one that grenaded.That one I had put on and never looked at again,thinking it was a new cast part and was bulletproof.I had just gotten up to speed,about 60 mph or so and it sounded like the engine was trying to jump out of it's mounts.It had big voids in the casting at the break.Just like the old four blades,one bad one doesn't mean that all others are bad.I'm not afraid of an aluminum fan because of it,I just know to watch it like the others.When you get the new one just make sure the blades are parallel,I saw one that had one blade a half inch ahead of the other.Also,blacken the taper on the waterpump shaft with a magic marker and spin the fan on it.That will tell you if there is good contact between the two.I changed one a couple years ago on an A,the owner said the fan was not seating right because of a bad taper.Turns out the problem was he had let the key ride up when he put it on,the taper was fine.He had read horror stories of how the tapers were off on some and it couldn't possibly be his careless installation.Also,use a hard washer between the nut and the hub.Without it the nut will start a cut into the soft aluminum hub.If you take one apart that has been run without a washer you can see the hex of the nut formed into the hub.

Re: Broken fan hub
 

I had a taper problem on an aluminum fan and found that I was bottoming out on the key which I ended up shaving down. It was going on a B pump so I don't know if that made any diff.

Re: Broken fan hub
 

When installing any fan on the tapered shaft with a key it is best to install it with out the key first and find out where it bottoms out on the shaft. Put a mark on the shaft at that point then put it on with the key in place. If you don't get to your mark you are having an interference problem with the key and need to fix that before moving on to finishing the installation.

Re: Broken fan hub
 

Best i can figure, it was the pot metal "core" in the hub, i'll get a couple pictures when I get it off the engine.

Re: Broken fan hub
 

Broken like the one at this link?
http://i29.photobucket.com/albums/c2...Roundup002.jpg

Re: Broken fan hub
 

Here are a couple quick shots.....the hub that the fan and pulley attach to broke at the attachmet face, this let the pulley wobble around on the hub. It looks like it had been broken for a while before I got the truck, as there are groves worn into the water pump housing.

And I do believe who ever did the 6v alternator conversion did over tighten the belt, causing this to happen.

Re: Broken fan hub
 

I agree that it appears the belt was overtightened.

Re: Broken fan hub
 

This is an engine shot from the PO's ad, he had it posted for a couple few months....but this showes the fan sitting upright and straight on the pump....so its hard to tell when it finally happened, the grooves on the pump were old and filled with dirt and grease. Maybe this is the 2nd time it happened to this poor truck.


All i know for sure is it ruined my ride to work, but didn't do any major damage to anything, just a couple bent fins on the radiator and the wear on the pump housing.

Re: Broken fan hub
 

The only thng I can see that doesn't look right in that picture is the belt is riding too low in the groove on the fan pulley.

Re: Broken fan hub
 

Eli, what in the world were you doing in the fast lane?

Re: Broken fan hub
 

ha, fast lane?....as long as I don't need to go over 45mph i'll use any lane I want....this is arizona also, every lane is a fast line. People will do 70 on the surface streets but only 55 on the freeway.

But in reference to cutting across 3 lanes, the turn to work was coming up, so I was in the "pre turn" lane.