Belt Driven Fan Catastrophic Failure

[JOEZ33]

Well I almost had a total explosive failure of my belt driven fan. Here's some pics of it. This one has 175,000 miles on it, and is 10 years old. I found the cracks while doing some routine inspecting around the engine area.

Just thought I'd show you guys so you know what to look for. If this thing had cracked any further it would have completely blown apart into the radiator, possibly the condensor, and probably would have gotten into the pulleys and broke the belt also. The dollar amount of damage plus towing would have easily been around $1,000.

I'm thinking that I'm not the only person with a fan in this condition, so you may want to go take a look at yours. The cracks are in between each blade at the base/hub of the fan. Mine has about 20 cracks in it, some have separated over 1/8th of an inch.

 

[BrooklynBay]

I found a very minor crack on the fan on my 93, but it's not as bad as this. It has almost 190k miles.

 

[Willard]

Both fans that have been on my explorer are/were cracked. The one now is maybe 2 years old. I had to attempt to cut the old, cracked one off the face clutch. Nearly impossible, trust me, the plastic won't shoot off, it's not going anywhere.

 

[BrooklynBay]

I saw that some auto parts stores sell Hayden metal fans. Do they make them for the 4.0L? If so, would it be better to put a metal one in instead of the plastic one?

 

[JOEZ33]

... I had to attempt to cut the old, cracked one off the face clutch. Nearly impossible, trust me, the plastic won't shoot off, it's not going anywhere...

I don't trust it AT ALL. No way in hell, I work on aircraft and saw tons of video footage in college showing the effects of a spinning object, i.e. fan blades when the hub is cracked. At 1 rpm it's already creating at least one G depending on the blade length. Imagine at 2,500 rpms or even 5,000 rpm's... Those blades probably only weigh a few ounces each, but at 2,500 rpms they are pulling outward at an extremely high force. That's no problem at all as long as the hub is solid, but with a crack in the hub it allows the blades to swing and move out of track, out of balance, cause vibrations through the water pump bearing, and can explode. There's no way you can possibly pull on it with your hands and duplicate all the motions it goes through while turning on a running engine, with 180 degree air going past it etc.

I know it's not the same as a 72" aluminum prop on a cessna, bolted to a solid crankshaft and absorbing all the vibrations from the pistons, but it still goes through a ton of abuse.

 

[Hoppy]

My 92 ex had worse cracks in it and it lasted until the truck died with over 450,000 kilometres or 280,000 miles.

You have to remember the fan clutch is there to reduce RPM's of the fan as well. It will never see speeds of 5000 RPM.

 

[James909]

The fan on my Ex has a few cracks in the hub as well. It's on my list of things to replace. I agree that it is possible for these fans to basically explode if the cracks got bad enough. And if it does it could do some serious damage. I have a friend with an Audi (I know it's like comparing apples to oranges but the fan assembly is the same) that the crank driven fan exploded on. The radiator was destroyed and had to be replaced and the fan even dented the hood.

 

[Rick]

All of the Explorer fans I've seen have had cracks like that. It looks like they'll come apart at any time, but I have yet to hear of one actually breaking

 

[Cobraguy]

You know, I have seen a ton of these fans cracked. I have never seen a single one come apart from it.

 

[EMG7895]

the one on my old truck was cracked like that for years, i eventually replaced it anyways but i doubt anything would have happened.

 

[JOEZ33]

Man thats crazy, I would NEVER tell someone "hey don't worry about that cracked plastic fan, you'll be fine..." especially with the risk involved over a 52$ fan. I understand that with the clutch, and also with the reduction in rpm caused by the crank pulley being smaller, that the rpms are about 1/2 of the indicated RPM, but still, way too much at risk based on stories of people being lucky. Knowingly ignoring a cracked fan is about as bad as ignoring a bald tire with chords showing.

 

[Maniak]

Considering there are over 90k members on this site and the site has been around since the mid 90's (through various servers) and there has yet to be even one report of an exploding fan. I would say that it shouldn't be dwelled upon, but I wouldn't ignore it either. When you get the time/money replace it, but don't just "stop driving" because you see a crack. The crack in the early post on this thread is no worse than what I see on almost every 1st Gen x I ever look at.

If the fan were a poor design, and by poor I mean as in it would explode/break apart after it started to crack, there would have been many reports by now of exploding fans. I have to give ford credit.. those fans can last many thousands of miles with cracks and not explode. I know our first one went 355k miles and I know it was cracked when we did the transmision swap which was 70k before we rebuilt the motor.. and its cracked already (only 20k since it was installed)

~Mark

 

[BrooklynBay]

http://www.haydenauto.com/products/fan-clutches-and-fan-blades.htm

 

[410Fortune]

actually I have seen reports of the nylon fan hub coming apart, the fan took out the hood, radiator, belt, shroud, and more

The new 11 blade nylon fan frmo the dealer is like $35
if your fan has cracks (THEY ALL DO IF THEY ARE 10-15 YEARS OLD) replace it and upgrade to the 11 blade version

 

[Rick]

All of the Explorer fans I've seen have had cracks like that. It looks like they'll come apart at any time, but I have yet to hear of one actually breaking

I lied... I searched and I actually posted in a thread where two people wrote about their fans breaking. One at idle, the other on the highway. Damage was limited to a busted up fan shroud.

From now on I'll recommend replacing any fan with a cracked hub

 

[Maniak]

You must be a better searcher than I.. I don't remember ever seeing a thread with it breaking, but I can't remember what I had for dinner two nights ago either.. and I couldn't find a thread with one breaking apart..

At least we now know for sure it has happened.. but I still don't think its enough of a concern to panic, but it "should" get replaced.

~Mark

 

[410Fortune]

I had Pho with spring rolls LOL

 

[Willard]

I just thought it was weird because my fan I have now cracked within a year or so of being installed.

 

[JOEZ33]

Mines the 11 blade version and it's never been changed since we bought it in 1998.... it's a 1998 model.

I know they fail, I've seen it first hand from a friend of mine. His destroyed the radiator, the a/c condensor, the hoses, the belts, and actually broke the water pump housing. In addition the overheating caused a cracked cylinder head.

I will NEVER tell someone "...yeah sure go ahead and drive it down the highway....you'll be fine... don't worry, this web forum I was reading said there's nothing to worry about...some guy said he's seen cracked fans before and it's not a problem at ALL..."

Anyways, I started this thread TO HELP PEOPLE, and get people aware that there fan is probably cracked if it's 10 years old, and to make sure they take a good look at it. Whether they risk driving with it cracked is another thing, but at least I TRIED to help.

If you don't care or think it's a risk at all, then don't bother posting comments, if you have something positive to add like where to find a better fan, maybe other solutions like electric fans, or links to websites that have good prices- then please post your helpful comments.

 

[Willard]

I was just posting my experiences, sorry for screwing up your thread. I guess I figured I was helping somehow, stupid me