Radiator fan on my '06 tacoma always spins when engine is running.

My impression is that there is a clutch on this fan and the fan should only spin when the engine is warm enough to require cooling. My fan always spins as long as the engine is running. Is my impression incorrect or is there an issue with my fan?

 

There is enough drag in the clutch it will spin with the engine, it's never fully off/disengaged/static. This slight drag reduction is one reason things started to move to electric fans.

 

Clutch fan should always spin. That's one of the reasons they work so much better than e-fans.

 

That's normal. There is a fan clutch that is activated by the heat from the engine but even when it is cold and disengaged it still allows the fan to spin. It's useful because when it is disengaged it doesn't cause as much drag during acceleration (even thought it does catch up and spin with the engine rotation). If you want to confirm it's working properly, try to spin the fan when the engine is completely cold (and turned off). If it is loose and you turn it by hand, it's working. If it's locked up when it is cold, it's not working. If they aren't working they tend to make a scream when you accelerate.

 

They move a lot of air because the motor powering them is just sliiiiightly bigger than on the electric..which allow them to spin more, bigger, and/or more steeply pitched blades.

I'd actually be really curious to see a torque capacity rating for a fan clutch..

 

Yeah, plus the blades themselves are huge instead of flat. Most e-fan conversions can't keep up in Phoenix so I'll never switch, but in cooler climates it might be worthwhile if you're really after that extra 5hp. Even my buddies 1100hp MKIV Supra is still rocking a clutch fan.

 

Thanks everyone for the clarification and the fan does spin by hand when the engine is off, so I guess it's working properly.

 

It shouldn't spin so easy by hand. If it does, the clutch needs replacing.

 

This. There should be some resistance, but it should be movable.

 

There was some recent postings showing a failed fan clutch and the carnage it caused. So I unnecessarily replaced mine. I say unnecessarily because there was no difference between the new and old parts, they felt equally stiff. Peace of mind tho.

 

PM can be tricky. I tend to look at the consequences of the part failing - and how I'd feel afterwards about collateral damage. Sure, maybe it looks and feels fine, but blowing a hose and overheating in the middle of nowhere because I felt that it was not enough to operate 100,000 miles beyond it's designed service life? Maybe I have lost my sense of adventure in my olde age, but, no thanks..

 

I did the fan clutch when I did a water pump @150k this summer, the original was still good. Since I live in the desert and often see 100F + in the summer I pay close attention to cooling system performance using obd temp data. Usually a fan clutch is not immediately obvious when it goes bad and often doesn't fail completely so it's frequently mis-diagnosed.

Tested it out in Death Valley in 119F ambient temps also while climbing multiple mountain passes, the highest engine temps I saw were 219F which is well within the safe zone temp-wise. Considering the truck's environment, the carnage overheating can cause and the remote places I visit, erroring on the side of caution seemed like a no brainer.

 

The bad ones usually spin by hand when the motor is off also so don't use that as your yardstick. If it locked up and didn't spin (engine off) that would just soak up some of the engine's performance but the motor will still be cooled fine and you might not even feel the difference when driving or see any temp issues. It's when their temp controlled clutch slips and the clutch doesn't fully lock up in hot temps is when the problem occurs.

 

So for $80 I decided to go ahead and replace it. The trucks got 183K mi. so what the heck!

 

Mine roars for a few seconds right after initial start-up and then slows and quiets right down. I have only heard it activate (roar) one or two times in stop and go traffic on a really hot day. It quiets down again once the traffic clears. It sure moves a lot of air when it is activated.

 

Isn't it supposed to be "on" trying to be a black hole for the first 10-15 seconds on a cold start, and if it doesn't (or doesn't stop), that's an indicator of failing/failure? Swear I read that somewhere, but I may just be swearing.

 

Not sure if it's actually a feature of these devices or just how it normally settles after shut-down. I have had a few cars with this type of fan and they all did this. I haven't had any of them fail but if this did occur (no initial roaring) it would be a heads up for me that I would notice and check it.

 

Lots of aftermarket fan clutches are "heavy duty" and suck a lot more power than the OEM one.

Do not buy a "heavy duty" aftermarket clutch.

Also Toyota clutches almost never fail.