Toyota pickup question

[funkendrenchman]

I just got a couple of belts replaced on my 94 pickup and when I got it back I noticed the fan in front of those belts is constantly running producing a good flow of air when looking at engine with the hood up. Is this fan supposed to run constantly? I have never notice it doing that before. The engine temp also seems to be lower it was before the repair. Any ideas?

[bio-smear]

There's a sensor/switch that engage the fan clutch when the coolant temp reaches a certain threshold. Perhaps something in this little tryst has gone bad.

[funkendrenchman]

There's a sensor/switch that engage the fan clutch when the coolant temp reaches a certain threshold. Perhaps something in this little tryst has gone bad.

That's exactly what I thought, but the mechanic said it is supposed to be running all of the time. I'm not so sure.

[Arty50]

Yes, your fan should be running most of the time; especially when the vehicle isn't moving. The only exception is when the engine is very cold. Then the fan clutch disengages and lets the engine come up to operating temp before it re-engages. Generally when the clutch goes bad, the fan doesn't rotate properly (aka. too slowly). The fan will always spin when the engine is running, it just won't spin very fast when the clutch is disengaged.

[lemon boy]

I take it we're discussing a fan that is attached to the engine by a shaft, not a pair of electric fans. If so, the fan will always turn* when the engine is regardless of if the clutch is engaged or not. When the clutch is engaged then the fan will turn faster though. When cold the fan should spin easily by hand (engine off duh) and when warm, the fan should be harder to spin by hand (engine off duh)

*I've never seen one that was so freewheeling it could not turn when the engine was on.

[tigerstripe40]

There's a sensor/switch that engage the fan clutch when the coolant temp reaches a certain threshold. Perhaps something in this little tryst has gone bad.

Actually, it's a viscous fluid coupling, not an electronic sensor/switch.
When the fluid inside of the fan viscous fluid coupling reaches a certain temperature it acts 'more solid', allowing the fan to turn.

When the fluid is cool it acts 'more liquid' and the fan stops turning.

It should run most of the time.
How you tell if that's bad is to stop the motor. If the fan keeps turning, the viscous fluid coupling is bad and needs to be replaced.

[1000-oaks]

There's also the "leather glove" test (less likely to lose skin off your fingers), but I won't explain it due to potential liability. lol

[Bullet]

http://www.tacomaworld.com/forum/

[1000-oaks]

Tacoma didn't come out until '96, if memory serves. See www.pirate4x4.com , Yota section.

[runethechamp]

yotatech.com is your best friend.

But it does have that viscous coupleing with some kind of silicone liquid in it. When I start my 94 4runner, which I think should have a more or less identical engine to your pickup (if you have the V6), the fan turns for about 20 seconds or so until the liquid either heats up or gets distributed proberly in the coupleing. You can actually hear that when you start up and start driving. And people are right, it turns all the time, but not that fast when it's off. I think people saty you should be ablt easily stop it with your hand when it's dsiconnected, but I'd definitely put a glove on or use a small stick or something.

And no Arty, the fan doesn't spin full speed most of the time. It actually hardly ever comes on in my 4runner.

[Arty50]

And no Arty, the fan doesn't spin full speed most of the time. It actually hardly ever comes on in my 4runner.

A fan's purpose is to pull air over/through the radiator in order to cool the liquid inside. When the car is at normal operating temperature (which it should be most of the time), then you need to cool off the liquid somehow. If you're driving at highway speeds, then you don't really need the fan. The air traveling over the radiator is moving at sufficient speed to cool things off. However, when the car is not moving but the engine is at operating temp; you have to move air over the radiator somehow. The mere action of the coolant running through the radiator will not cool the fluid sufficiently.

So if the car's is running at operating temp and not moving, the fan should be running. There are exceptions to this, namely in very cold environments. In those environments your try either block the flow of air (ie. cardboard over the radiator) or push hot air over the radiator (ie. a push fan).

[runethechamp]

A fan's purpose is to pull air over/through the radiator in order to cool the liquid inside. When the car is at normal operating temperature (which it should be most of the time), then you need to cool off the liquid somehow. If you're driving at highway speeds, then you don't really need the fan. The air traveling over the radiator is moving at sufficient speed to cool things off. However, when the car is not moving but the engine is at operating temp; you have to move air over the radiator somehow. The mere action of the coolant running through the radiator will not cool the fluid sufficiently.

So if the car's is running at operating temp and not moving, the fan should be running. There are exceptions to this, namely in very cold environments. In those environments your try either block the flow of air (ie. cardboard over the radiator) or push hot air over the radiator (ie. a push fan).

Yes, that's how it works. BUT, on my 4 runner, since the fan is loud as hell, I can tell if it's on, and it doesn't happen very often. So I suspect that would be the case here too with a Toyota pickup. I'm pretty sure that fan doesn't turn on in city driving on a normal sunny day here. Maybe the radiator is superduperefficient or something.

[lemon boy]

because it apparently needs to be said:
DO NOT TRY TO STOP THE FAN WHILE THE ENGINE IS ON

jesus fucking christ. Between the fan and the belts that's a way to loose a finger like [SNAP] <---THAT! Seriously, you won't ever see a mechanic try that stunt. What's so hard about getting the thing to operating temp, turning it off and seeing how the fan moves relative to cold?

As for how efficient the fan/cooling systems are:

Cooling systems are generally designed to function at the very limit of a vehicle's rated capacity, in very hot weather, on very long, steep grades. Driving around in traffic on a hot day is hardly a test of a truck's cooling ability.

[Hook]

You know L.B., you just rained on Max's next T.R.

[lemon boy]

I don't expect my advice to necessarily stop max from doing anything. Besides, his suby has an entirely different setup that would be MUCH less dangerous to stick your fingers into (j/k max, don't do it!)