fan clutch question

[Lanky]

Got home after driving 2-3 miles from football game and popped hood to check a/f leak. Noticed that my fan was starting to show cracks, started engine and throttled it up to 2-3 grand and noticed that the fan did not slow down. It was @ 50 degrees outside and we had not driven that far. Shouldn't the clutch let the fan slow down to where it looks like you can stop it by hand at high rpm's? Mine feels like a tornado at 3000 rpm's. Would love to do e-fan but too much involved for wiring and amp draw/relays.

 

[Maniak]

They don't completly disconnect from the motor.

For an extreme example, The Hyaden Server duty fan clutch spins the fan at 30% of shaft speed even when its disconnected.

The other one (I think OEM) said it spun the fan at 20% shaft speed which means at 3000 rpms its still spinning 600 rpm which will still look pretty fast.

Also, Fan clutches seems to be very tight at initial startup and then loosen up once its been running a minute or so (not warmed up, just spinning I guess).

Either way.. I doubt any hydraulic fan clutch should ever make a fan look like you can stop it with your hand.

~Mark

 

[Fifty150]

Would love to do e-fan but too much involved for wiring and amp draw/relays.

Check out my electric fan install.

 

[SoNic67]

That is a nice electric fan install, but wrong. You are measuring the temperature at the INLET of the radiator - water that exits from the engine. And trying with that "info" to control the fan that cools down the water that EXITS the radiator. It "works" because the thermostat adjusts, but really you are working it hard (open-close)...

If you install the probe to the exit (OUTLET), you will control the temperature of the water exiting the radiator. You will provide constant (almost) temperature water to the engine, with a fast response time of the regulator, so the thermostat doesn't have to work that much.

Look here: http://en.wikipedia.org/wiki/Control_theory
You have a typical feed-back control loop.

The Controller is the fan relay/fan. The System is the radiator - that you act upon with the Controller. The Sensor is your temperature probe and should read the output value of the regulated System (water exiting the radiator).
Right now you have the Sensor reading the temperature after another System in the path - the engine block - with another Controller - the termostat - and you don't control directly the temperature in that system with your fan. There is no reason to include those in the fan loop.

 

[Lanky]

I think one of the first things i really need to address is the cracks in the plastic fan. I really don't want to end up replacing a radiator. Fan clutch is about $60 for a V6 and $100 for my V8, I'm guessing there is a cfm difference for the V8. The fan write-up above is sweet! How is it working for you? Any issues?

 

[imp]

Trucks Use???

I think one of the first things i really need to address is the cracks in the plastic fan. I really don't want to end up replacing a radiator. And you easily could! Ford started using plastic w/clutch in Mustangs, like 1989, had rash of cracks around hubs, changed composition. They definitely can come apart.
Fan clutch is about $60 for a V6 and $100 for my V8, I'm guessing there is a cfm difference for the V8. There are several designs of clutch, beyond just CFM rating. Some use a thermostatically-rotated set of vanes within, which work in conjunction with the negative-viscosity coefficient fluid within to regulate fan power input. Some lack this thermostat, cost less, are less effective; the thermostat is a coiled flat-cross sectional spring mounted on the front of the clutch, exposed to the airflow coming through the radiator; the "rotation" of the spring with temperature change is transferred to the vanes within through rotation of a shaft entering the front of the clutch, being affixed to the center of the spring coil.
The fan write-up above is sweet! How is it working for you? Any issues? Electric fans are OK, but ask yourself, why have we never seen a heavy-duty truck which uses electric? The mechanical fan blade driven by viscous clutch is in my opinion (!) one of the best answers to the cooling dilemma. Watch the FLACK start flying, now!!

Check if the clutch bearing is seized up, causing constant fan drive: Rotate blade with your fingers with engine off, obviously; it should turn freely. Any binding is BAD. The blade itself is removable from the clutch; if this were my application, I would change them both. Electric fans SUCK, but just not enough, IMO. imp

 

[Fifty150]

That is a nice electric fan install, but wrong. You are measuring the temperature at the INLET of the radiator - water that exits from the engine. And trying with that "info" to control the fan that cools down the water that EXITS the radiator. It "works" because the thermostat adjusts, but really you are working it hard (open-close)...

If you install the probe to the exit (OUTLET), you will control the temperature of the water exiting the radiator. You will provide constant (almost) temperature water to the engine, with a fast response time of the regulator, so the thermostat doesn't have to work that much.

Look here: http://en.wikipedia.org/wiki/Control_theory
You have a typical feed-back control loop.

The Controller is the fan relay/fan. The System is the radiator - that you act upon with the Controller. The Sensor is your temperature probe and should read the output value of the regulated System (water exiting the radiator).
Right now you have the Sensor reading the temperature after another System in the path - the engine block - with another Controller - the termostat - and you don't control directly the temperature in that system with your fan. There is no reason to include those in the fan loop.

No arguments from me. What you said makes perfect sense. I am not an expert, and I didn't engineer the system. The installation instructions from Derale were to put the probe "as close to the water inlet as possible". See step 2 below. Their idea. Not mine. My Troyer electric fan kit has the probes (there are two, one for each fan) in the middle of the radiator, along the top rows, and between the fans.

 

[Fifty150]

How is it working for you? Any issues?

None what-so-ever. However, it is still new.

A few issues I had were with the installation. Mistakes that I made. Thanks to the excellent tech support over the phone from Derale, I got my fans running.

The green color over-ride wire which connects the A/C to the 85 post on the relay has an inline diode. When I tested the wiring with a multi-meter, the diode prevented me from "seeing" connectivity. I cut it off, and later, had to splice it back in. The diode prevents feedback. Without it, fuses were blowing.

Above and behind my driver side headlight there is a stud with several ground wires already attached. Lighting units were on the stud with ring terminals in direct contact to the body. That was followed by a nut, a ground line from the battery, and another nut. I tried to add the fan and relay controller ground on top of that second nut. That may have resulted in insufficient grounding, which causes fuses to blow. The solution was to ground directly to the negative post of the battery.

I then eliminated the fuse holder entirely and wired the relay directly to the fan. Then I added a circuit breaker inline from the positive battery post to the 30 post on the relay to protect the entire system. Circuit breakers reset themselves, so no need to check and change fuses. The danger in the fuse system is that when you are driving and the fuse blows, you may not know it blew, until your car starts overheating and you wonder why your fan has not turned on. This was done after consulting with Derale.

The "Scotch-loc Connector" that allows you to tap into the A/C wire sucks. It just does not work. That little piece of metal that is suppose to snap into the wiring did not cut through the plastic to actually make contact with the copper inside the wiring. Splice and solder for best results.

 

[Lanky]

I noticed that you went from a single fan to a dual fan setup, did the single not do good enough? I would like to do a single fan with 2500 to 3000 cfm fitted inside my existing shroud so that you pull air through the entire radiator. But at about 300 bucks for a kit, i don't see it happening soon.

 

[Fifty150]

I noticed that you went from a single fan to a dual fan setup, did the single not do good enough? I would like to do a single fan with 2500 to 3000 cfm fitted inside my existing shroud so that you pull air through the entire radiator. But at about 300 bucks for a kit, i don't see it happening soon.

The dual fan set-up is on my F-150.

My Explorer has a single fan Derale combination. It cost about $200. You can install the fan with the factory shroud.

 

[SoNic67]

What size is the fan in the picture? Looks like it needed to be a little bigger.

 

[my98nnj]

I diagree with what Sonic said about where the probe is.

Every coolant related sensor signal to the vehicles ECU, including electric fan operation is typically on the engine outlet side, T-Stat housing. The radiator is not the system your controlling, the engine temperature is the system your controlling. Placing the probe on the outlet of the radiator is only measuring the coolant temp after it's been cooled down. That's not what you should be looking at. It's the water temp as it's coming out of the engine that you should be looking at as that's the engine's operating temperature.

The directions in the kit are correct with where to place the temp probe.

 

[Fifty150]

In theory, the temperature probe turns on the fan at 180. That is the temperature of the cooling fins on the radiator, not the coolant inside the rows of the radiator. With the probe near the inlet (upper hose), the actual temperature inside of the engine is at or above 190. Let's assume that we know that the radiator will dissipate heat by another 10 degrees. With the probe near the outlet (lower hose), The internal temperature of the coolant and cylinder head could easily be in the area of 200 - 210 when the fan turns on. Either way, I don't see failure or disaster looming.

 

[Fifty150]

What size is the fan in the picture? Looks like it needed to be a little bigger.

Derale 16217

--------------------------------------------------------------------------------

Part Type: Electric Fan

Specifications
CFM high/low: 2400/1800
Amp draw high/low: 23.5/17.4
Width: 16-7/8"
Height: 16-7/8"
Depth: 2-5/8"
Mounting: 8-7/8" x 15-5/8"

 

[Fifty150]

I think you can find fans of all sizes in diameter. The problems is the depth. With just about 3.5" between the radiator and the water pump stud that the fan clutch mounted on, I wanted a fan that was less than 3" in depth in order to fit it in comfortably. There are probably other fans of different dimensions that other companies offer. I don't know. I found this one from Derale with 2400 CFM, and I felt comfortable with the cooling capacity.

 

[Maniak]

I diagree with what Sonic said about where the probe is.

Every coolant related sensor signal to the vehicles ECU, including electric fan operation is typically on the engine outlet side, T-Stat housing. The radiator is not the system your controlling, the engine temperature is the system your controlling. Placing the probe on the outlet of the radiator is only measuring the coolant temp after it's been cooled down. That's not what you should be looking at. It's the water temp as it's coming out of the engine that you should be looking at as that's the engine's operating temperature.

The directions in the kit are correct with where to place the temp probe.

As I see it, the issue with using those after market fan controllers and putting them in the "hot water" is the non adjustablilty of the turn on versus turn off temp.

Most controllers I have found (even the adjustable ones) let you control the turn on temp, but not the turn off temp. In addition, they seem to have a 20F swing between on and off.

That means if you were to read the hot water (say just after the thermostat) and set it to say 210F (15F over thermostat temp) the fan would turn on and not want to turn off until the coolant was down to 190F. That means the fan would most likely not turn off. since that temp is lower then the thermostat temp and the coolant would never drop below the thermostat temp.

OEM/ECM control of the fan can have much more precise control. They can set when to turn on and off the fan at whatever temp they want. I would guess that they watch the coolant temp coming out of the motor and using the fan try to keep it just above the thermostat temp, but that is just my guess.

I have installed a Dakota DAC-2000 fan controller on an f-150. That controller let us control the turn on and off temp of the fan. We have it reading the hot water and have it set to turn off about 10F below the turn on temp which is slightly higher than the thermostat temp. It is controlling things just fine.

On our Van I tried it reading the hot coolant and the cooler coolant. With the hot coolant (just out of the intake) I would have to let the motor get very hot before the fan would turn on if I wanted the fan to turn off when I was going down the freeway (had to set it so the turn off temp was hotter than the thermostat temp). In addition to turning on later than I liked it was swinging the engine temp 15F-20F.

I then moved it to the lower part of the radiator (not bottom, but about 1/3 way down). I now let the thermostat keep the motor at the temp it wants and the fan keep the coolant coming out of the radiator < 170F (measured at the fins). Now the engine temp swing is < 7F where it was upwards of 20F when I read the hot temp.

BTW.. if you want to use those point/shoot (laser) temp sensors you need to make sure the material is non reflective as that will throw off the readings. To keep all things equal, if I'm measuring temperature on different material (or color material) I put a piece of electrical tape where I want to read each piece and measure on the electrical tape.

~Mark

 

[Fifty150]

My controller has a "fixed" turn on of 180. Pretty simple for me. Do I want the fan to turn on at 180 at the inlet or outlet.

 

[Maniak]

The Derale 16217 is an on at 180F and off at 170F. That means you need to find the right spot that turns it on before the motor gets hot, and turns it off when your cruising down the freeway.

With temps that low you can't put it in the "hot water" at the thermostat housing or right off the the intake as it would never turn off.

In your case, I would put it somewhere that does not have fan coverage (the air blowing across it will make it read incorrectly at idle and make it cycle on/off/on/off quickly). As for how high on the radiator, I would say higher than the bottom 1/3rd.

We have our set at 1/3 from the bottom and turn the fan on at 167F and have a 20F diff between on/off. For yours, I would say not right at the radiator intake, but maybe towards the outlet side. You want cooler water, but not so cold that the fan doesn't turn on in time.

Without having the ability to adjust the temp, your only choice is to move it around. If where you have it now keeps the motor cool and doesn't make the fan run when its hot out while your going down the freeway then leave it where it is.

~Mark

 

[Fifty150]

So far, it is working fine. Keep in mind that the OEM thermostat opens at 190. Hot coolant comes out at 190, goes through upper hose to radiator, fan turns on. Fan cools radiator fluid, or fluid is cooled from airflow from freeway, thermostat will close, and fan turns off. It actually does work. I've tested the fan in my garage and have seen it turn off after sufficient cooling has been achieved.

 

[Maniak]

Normally, the thermostat doesn't close all the way, so its always letting some hot water through.

It sounds like you have it far enough away from the radiator inlet that its not reading the really hot water which is good.

All you have left to check is make sure that on a hot day (kinda hard to do today, unless your in Sourthern AZ as its gonna be 90F here today) that as your driving down the freeway (55 mph+) that the fan stays off.

When I first installed the controller in the the radiator (where it is now) I had the turn on temp a little too low and once on the freeway it would sometimes turn on the fan. I raised the turn on temp a little (up to 167) and now it doesn't turn on even with its 105F+ out and I'm on the freeway.

All in all, I think you have a handle on it.. You just have to play with the location to dial in where you want it to turn on/off in the hot and cool times of the year..

~Mark