Diagnose a bad fan clutch?

[tgibbonsfordluv]

96 AWD XLT with a 5.0. I did a water pump on this thing back in June of this year. Had all the classic problems of broken bolts, removing the timing cover and so on.

Today my water pump just went out again. Something isn't adding up here. There's no way in my mind a water pump bearing should go so quickly (though I've probably put around 6-7k miles on it since). Makes me think I have a bad fan clutch binding up and putting excess strain on the pump bearing. It's either that or my pump was defective.

The clutch has some resistance to it when I spin the fan but it does fee spin. Any way to test it beyond that or is it good?

 

[1998Exp]

The clutch responds only to temperature, so you could put it in a refrigerator (which should cause the resistance to go down), then in an oven set to 100 degrees or some such (which should make the resistance increase). But I suspect that the fan clutch has nothing to do with your pump failure - the bearing should not be affected much by the slightly increased tension on the belt, even if the clutch seizes completely. After all, people drive in 100 deg weather all day long, and nothing happens.
Perhaps the fan is out of balance and shakes the pump bearing pretty bad. And by the way, what does the coolant look like? Bad coolant, which lost its lubrication properties could cause premature water pump demise. If none of the above, I would suspect the pump - especially if it was a cheap or remanufactured one.

96 AWD XLT with a 5.0. I did a water pump on this thing back in June of this year. Had all the classic problems of broken bolts, removing the timing cover and so on.

Today my water pump just went out again. Something isn't adding up here. There's no way in my mind a water pump bearing should go so quickly (though I've probably put around 6-7k miles on it since). Makes me think I have a bad fan clutch binding up and putting excess strain on the pump bearing. It's either that or my pump was defective.

The clutch has some resistance to it when I spin the fan but it does fee spin. Any way to test it beyond that or is it good?

 

[tgibbonsfordluv]

I don't think the clutch responds to temperate. Not from other things I've read. The point of the clutch is that it keeps the fan from doing as many rpms as the engine. They're supposed to max out around 2200rpms.

Naturally I changed the coolant when I last changed the pump, that is to say it's still good.

 

[Sedition]

You can here the fan 'Roar' from inside the cab when it's engaged.

If it isn't roaring on occasion and then kicking out again it's broken.

If it's constantly roaring and not kicking out, then it's also broken.

It's Winter in the US so it's probably not gonna roar much and when it does, it won't be for long.

It's Summer here (extremely hot) and my fan roars all the time unless i'm on the highway doing 80 (kph, that is) Also I have a single core radiator until I have a spare 5 minutes to change it.

I would closely examine the belt on the pully while it's running and see if the belt moves from side to side, because of another bent pulley maybe?

 

[1998Exp]

You are entitled to your opinion.

I don't think the clutch responds to temperate. Not from other things I've read. The point of the clutch is that it keeps the fan from doing as many rpms as the engine. They're supposed to max out around 2200rpms.

 

[tgibbonsfordluv]

The water pump is shot. It's leaking and the belt walked off of it last night. I put thee belt back on and I can clearly see the pulley is not aligned with the rest of the belt assembly.

I found a pretty good article on fan clutches. I was mistaken as some of them are thermal. But it sounds as if you should almost always replace them when you replace the water pump. The one under my hood free spins a little and will then hit some resistance before free spinning again. It doesn't sound as if it should do that. It also sounds as if that added resistance in the fan clutch will most certainly strain the water pump bearing.

http://www.haydenauto.com/Fan Clutch Tutorial-Part 1/Content.aspx

 

[1998Exp]

The OP has the 5.0L engine, with a mechanical fan. I am not familiar with your SOHC, but sounds like it has an electric fan - quite different beasts.

You can here the fan 'Roar' from inside the cab when it's engaged.

If it isn't roaring on occasion and then kicking out again it's broken.

If it's constantly roaring and not kicking out, then it's also broken.

It's Winter in the US so it's probably not gonna roar much and when it does, it won't be for long.

It's Summer here (extremely hot) and my fan roars all the time unless i'm on the highway doing 80 (kph, that is) Also I have a single core radiator until I have a spare 5 minutes to change it.

I would closely examine the belt on the pully while it's running and see if the belt moves from side to side, because of another bent pulley maybe?

 

[tgibbonsfordluv]

You can here the fan 'Roar' from inside the cab when it's engaged.

If it isn't roaring on occasion and then kicking out again it's broken.

If it's constantly roaring and not kicking out, then it's also broken.

It's Winter in the US so it's probably not gonna roar much and when it does, it won't be for long.

It's Summer here (extremely hot) and my fan roars all the time unless i'm on the highway doing 80 (kph, that is) Also I have a single core radiator until I have a spare 5 minutes to change it.

I would closely examine the belt on the pully while it's running and see if the belt moves from side to side, because of another bent pulley maybe?

They're good trucks at 80 Mph too.....

 

[tgibbonsfordluv]

Long story short, I'm forking out the hundred bucks for a new clutch.

 

[Sedition]

The OP has the 5.0L engine, with a mechanical fan. I am not familiar with your SOHC, but sounds like it has an electric fan - quite different beasts.

No, it's mechanical. Like the V8 fan. There's a bi-metal spring on the front of the mechanical fan clutches. Warm or hot air flowing over the bi-metal spring will make the spring turn the spigot in the middle. It is the spigot shaft in the centre of the fan clutch that makes it kick in and out.

Hey OP. Be sure to unhook the bi-metal spring and exercise your spigot shaft back and forth many times until it frees up before you install your new fan clutch or it may not function correctly. (won't speed up the fan and make it roar)

 

[tgibbonsfordluv]

No, it's mechanical. Like the V8 fan. There's a bi-metal spring on the front of the mechanical fan clutches. Warm or hot air flowing over the bi-metal spring will make the spring turn the spigot in the middle. It is the spigot shaft in the centre of the fan clutch that makes it kick in and out.

Hey OP. Be sure to unhook the bi-metal spring and exercise your spigot shaft back and forth many times until it frees up before you install your new fan clutch or it may not function correctly. (won't speed up the fan and make it roar)

That's a nice thought, but it's too late. Just wrapped up a while ago. So dang cold today it's hard to know if it's working or not. Truck hardly heats up in this weather. God bless the midwest.

I'll know in the spring I suppose. Even a cruise at 80mph wont use the fan cause the air is so cold.

The old one was really bad though. Had thrown its bearing causing the pump bearing to follow. Hundred bucks well spent and a useful pump warranty, even if my own negligence required its use.

 

[Sedition]

That's right, at least you'll know what's up if your truck heats up in warmer weather. I envy the US and her cold weather right now, it's hot as Hell over here.

 

[1998Exp]

Thanks for pointing out this article. Nice explanation, though I'd take their recommendation to always replace the fan clutch along with the water pump with a grain of salt -- they are in the business of selling these clutches.

This whole arrangement, which makes a bad fan destroy the water pump, and both of them twisting the timing cover out of shape until it leaks coolant (which has no business being inside the timing cover in the first place) probably came from the Ford T era. The second generation Explorer might have been one of the last vehicles designed that way; everything else that I have seen - even my 11-year old Crown Vic - has an electric fan attached to the radiator, and the water pump attached directly to the block.

I found a pretty good article on fan clutches. I was mistaken as some of them are thermal. But it sounds as if you should almost always replace them when you replace the water pump. The one under my hood free spins a little and will then hit some resistance before free spinning again. It doesn't sound as if it should do that. It also sounds as if that added resistance in the fan clutch will most certainly strain the water pump bearing.

http://www.haydenauto.com/Fan Clutch Tutorial-Part 1/Content.aspx

 

[tgibbonsfordluv]

That's right, at least you'll know what's up if your truck heats up in warmer weather. I envy the US and her cold weather right now, it's hot as Hell over here.

I'd gladly trade. I'm in the northern US.

 

[tgibbonsfordluv]

Thanks for pointing out this article. Nice explanation, though I'd take their recommendation to always replace the fan clutch along with the water pump with a grain of salt -- they are in the business of selling these clutches.

This whole arrangement, which makes a bad fan destroy the water pump, and both of them twisting the timing cover out of shape until it leaks coolant (which has no business being inside the timing cover in the first place) probably came from the Ford T era. The second generation Explorer might have been one of the last vehicles designed that way; everything else that I have seen - even my 11-year old Crown Vic - has an electric fan attached to the radiator, and the water pump attached directly to the block.

I think all the Windsor blocks are designed this way. Those vics have a different generation engine. I wouldn't worry about the timing cover getting twisted up, it's pretty well bolted down. I had it off the last time I did a pump.

It does make sense though that a bad fan bearing will wreck the pump bearing, and vice versa. Vibration in a shaft is hell on bearings. I think their thought is that if one goes bad, it has already damaged the other.