So I never really thought about it, until tonight when a friend mentioned it to me. My radiator fan is on all the time. Is that supposed to be like that, or should it shut off?

 

Dean, the fan should turn all the time, but the clutch shouldn’t be engaged all the time...this si also being discussed in here: https://www.dieseltruckresource.com/...d.php?t=181696
Here is what I just posted there:
if the fan clutch is frozen and the fan is turning all the time, you'll have a cool system. It is only supposed to engage when the engine is hotter than what the rad can cool by itself......
Open the hood, with the engine running and watch the fan while you shut it off... it should free wheel for a few seconds before stopping... if it lurches to a stop with the engine, then the clutch is bad.. Conversely, if you can grab the fan (engine shut off) and spin it with no resistance, it has frozen in the "off" position....and won’t engage when needed...


I should explain.. The fan clutch is well, kind of like a gel-pack ... the fan WILL turn all the time, but not at a 1:1 ratio with the engine.. the "gel" allows for slippage that lets the fan rotate much slower than the engine speed in RPMs....when it locks, the fan is turning at the same RPM speed as the engine, and "over-cooling" it.
There is a clock-spring looking piece in there that engages when it gets hot enough and locks the fan to the engine shaft....that is when the fan is designed to "come on" and spin faster, adding additional cooling..... When the gel gets too liquid or leaks out, the fan won’t engage when needed and runs too slow
Make sense? This is a simplistic explanation, but it is the basic idea of how they work...Hope this helps!!

 

thanks chrisreyn, my fan comes to a stop with the engine, which as you were saying is a bad clutch, so is it really going to hurt anything with the fan like that?

 

If your fan is locked, such that it turns all the time, it WILL NOT hurt anything, except maybe to take a lot longer to make heat.

I purposefully "PIN" fan-clutches all the time, just so that they will be direct-drive and turn all the time.

Contrary to popular belief, I never notice any drop in power or mileage.

 

I wont argue with experience, which is what Bk has, however , in theory, having the clutch engaged all teh time will decrease your fuel mileage slightly,perhaps impercetibly, because the engine is gonna run to teh cool side of its operating range all teh time, making it less efficent.
Whether its noticable or not is an arguable point I think.
If you are towing orhauling most of the time, it might make sense to lock teh fan on, for day to day driving, I cant see it being an advantage.

 

I will add that I won't "PIN" a fan-clutch that is behaving as it should and not causing a problem.


What I found works out real well for the wife's truck is that I install a "PINNED" clutch about mid-MAY and replace it with a normal clutch about mid-September.

The issue she was having was that the A/C (every piece part and particle BRAND NEW---EVERYTHING) did not cool efficiently in stop-and-go traffic, and during periods of idling; there just was not enough air movement across the condenser.

After going through four clutches, to no avail, I "PINNED" a junker and instantly her A/C problems were cured. (and the guys at the A/C shop were amazed)

She doesn't need the constant fan in fall/winter temperatures, so I swap on a normal clutch for the cooler months.

 

well that may be my prob also as i also do not get enough cooling in stop and go traffic , but cools as soon as i go 20 mph or over.

got my truck in cold weather and fan clucth was locked so i replaced it when i did kdp . so maby there was a reason it was locked ???

how do you pin the clutch ?

 

That makes perfect sense

 

Dean, you can take the fan off for the winter if your truck isn't a tow rig. It will run cool enough as long as the outside temp doesn't get much over 50. Mine is fanless right now.