Does anybody have an idea about why I'm hearing my radiator fan now almost all the time? Upon further investigation today, I popped the hood and listened to it at idle. It appears to not know whether to run or not. It starts to really turn, then backs off a bit, then goes faster, then slower. It's cold here (about 35) so I know the engine doesn't need the extra cooling. Is there a sensor for this fan that could have been messed up when they did the body lift? That's when I started noticing it (immediately). It's going back to the shop, but I'd like to know what I'm talking about when I go. Anybody?

 

Body lift you say?

Did that involve removing or modifying the radiator fan shroud?

As I recall, the fan clutch is controlled by a temperature sensitive spring. I have known these to 'go out" and the clutch is fairly inexpensive and easy to replace.

I am still thinking of the body lift.....could this new awareness of the sound be related to the repositioning of the body?

 

What engine are we talking about here?
Does it have a clutch fan or electric?

 

slarson

Yes, we don't know what motor you have or what your working on.

But it sounds like you are talking about a fan clutch that can't make up its mind whether to engage or disengage.

 

If you end up needing a new fan clutch don't buy an aftermarket one ($70.00). I and many here have had trouble with them staying locked up a very long time and will even lock up when you stop at a stoplight. I tried 2 different ones from well known manufactures and both were the same. The truck sounded like a jet for the first mile. After the clutch freed up the truck would take off and the noise went away. I bought a used one from the local junkyard for $35.00 and no problems. Dealer price was $120.00.

 

Sorry. I should have given more info. The truck is a 2001 Supercrew with the 5.4, automatic, stock fan not electric. I definitely noticed the difference right after the body lift. They have looked at it once and mad some adjustment, but I don't really think it helped. The fan shroud looks like it's been lowered with some brackets about 3 inches, which is what the body lift was. The Saint, this new positioning of the body could account for my awareness of the noise, but it runs almost all the time, and seems to have a hard time knowing when to kick in and when not to. The spring sensor makes sense to me, gets too hot it kicks in, otherwise it doesn't. Something's happened so that it doesn't know what to do. It just seems strange that it started when I had the lift done. Davet, when it locked up, did it stop the trruck from going or just make a lot of noise?
Thanks to all.

 

Sorry. I should have given more info. The truck is a 2001 Supercrew with the 5.4, automatic, stock fan not electric. I definitely noticed the difference right after the body lift. They have looked at it once and mad some adjustment, but I don't really think it helped. The fan shroud looks like it's been lowered with some brackets about 3 inches, which is what the body lift was. The Saint, this new positioning of the body could account for my awareness of the noise, but it runs almost all the time, and seems to have a hard time knowing when to kick in and when not to. The spring sensor makes sense to me, gets too hot it kicks in, otherwise it doesn't. Something's happened so that it doesn't know what to do. It just seems strange that it started when I had the lift done. Davet, when it locked up, did it stop the trruck from going or just make a lot of noise?
Thanks to all.

 

Sorry. I should have given more info. The truck is a 2001 Supercrew with the 5.4, automatic, stock fan not electric. I definitely noticed the difference right after the body lift. They have looked at it once and made some adjustment, but I don't really think it helped. The fan shroud looks like it's been lowered with some brackets about 3 inches, which is what the body lift was. The Saint, this new positioning of the body could account for my awareness of the noise, but it runs almost all the time, and seems to have a hard time knowing when to kick in and when not to. The spring sensor makes sense to me, gets too hot it kicks in, otherwise it doesn't. Something's happened so that it doesn't know what to do. It just seems strange that it started when I had the lift done. Davet, when it locked up, did it stop the trruck from going or just make a lot of noise?
Thanks to all.

 

When it was locked up the truck was very sluggish and made a ton of wind noise. The second that the fan unlocked the noise would stop and the truck would really accelerate as if you just unhooked a heavy trailer.
Did you make any compensations for the fan shroud being moved? Maybe the air is being disrupted behind the radiator rather than being held in by the shroud and the clutch temp sensor is getting varying air temps ( some cold from fresh air and some hot from behind the radiator)

 

I have the same truck/engine, and my fan does the same thing. I was told it's fine. There was a thread on it last winter.

 

Here is my theory on the issue: When the body goes up it brings the rad with it. The rad mount is part of the body. They have to cut two mounting tabs off the shroud to let it remain at engine/frame level and add clamp adapters to hold it in its new position. So if you look closely on a body lifted truck you will see a gap of 3 inches under the fan shroud where there is no rad. This allows a lot of air to go around the rad and amplifies the noise of the fan.

regards

Jean Marc Chartier

 

Thanks for the info. I don't know what kind of compensation should be made for the shroud being moved. It seems to be worse when it's cold outside and the engine is cold.

 

My observation is that the fan will not "free spin" for a few minutes on a cold fan. They roar when you first start them bacuse they use a viscous fluid in them that couples the fan to the shaft. The fluid is cold and thick and needs to warm up a bit. The bimetalic spring will also react to hot temps and activate the fan.

The first 5 minutes of engine operation casues the roar for me. As the slip in the fluid causes heat the fan slows down. Then it doesn't tighten up again unless the fan gets hot.

I personally like this type of a fan, despite its shortcomings. If you have ever considered a set of electric fans, there are nice kits available. A new fan clutch is the price of a nice down payment on them.

 

JMC,
Interesting ideas. I, too, saw the opening from the top of the shroud to the radiator. I wondered about this opening. What about putting a piece of something (plastic, sheet metal) there to block the gap?

 

Dave,

The fan clutch on my 89 F150 is locked up tight as a drum, so my fan roars at any rpm over about 1500. My local Ford dealer wanted $135 but didn't have it in stock, NAPA wanted $95 but didn't have it in stock. So I ordered from an online store I've used for my old car parts. I got a new Motorcraft clutch, that I would think does not fall into the "aftermarket" category, as it carries the Motorcraft/Ford labeling. My cost is $82 to my door, just showed up today. This is the one that specs for an A/C truck too, but not the Heavy Duty version. In fact there's specs that even state not to upgrade to a HD clutch on a truck that came w/o the HD version. I've never had overheating problems as long as I've owned the truck, so I figure this Motorcraft unit should do the job. What would the Ford dealer provide, that they want $135 for? I would think Motorcraft...?

BTW, I'm planning on doing the clutch this weekend, the roaring is driving me NUTS! Haven't done one of these before, any tips/tricks to suggest?