lower temp fan clutch

mine is a 15 year old fan, 15 year old water pump, and 24 year old untouched radiator and i have never much past 200 with the fan, i have seen 210 pulling a grade with no fan but 190 with the fan

I just tested one of my 3 clutches, the worst one is very loose and adjusting the spring has no effect at all (if anyone wants it for testing or pinning let me know). So a "good" clutch is a must. Both of the others are very stiff to turn and the one I just picked up at the JY for $5.00 looks to be brand new, not even any dirt on it. I'll try adjusting the older one and see how it works.

vegas39 said:

Dont know why so many have issues with replacement or factory fan clutches.
I bought a Hayden fan clutch at napa 2 months ago and cant get this thing to go over 210, even pulling long grades and you know how hot Vegas gets.

I notice that it fully locks in between 205 and 210.

Even with my old factory clutch, it was fully locked in at the same temps.

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Best get another to throw behind the seat at the rate haydens fail . I got to where I refused to install the things on customers cars the failure rate is so high on those things

RLDSL said:

Best get another to throw behind the seat at the rate haydens fail . I got to where I refused to install the things on customers cars the failure rate is so high on those things

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Agreed.

NAPA clutches are Haydens.

When I had the wife's truck (1991 Dodge/Cummins) at the local A/C specialists, who also happen to be a NAPA car-care center, having NAPA endorsement and using almost strictly NAPA parts, after replacing every single piece of the A/C save the evaporator, every hose, everything, they decided the fan-clutch was shot.

They went through THREE brand-new NAPA Haydens, then called me and asked what I wanted to do.

I said " dig my old junker out of the dumpster and I will learn you guys a new trick".

I took the old lifeless clutch home, drilled and pinned it, took it back and installed in on the truck, and problem solved.

RLDSL said:

Best get another to throw behind the seat at the rate haydens fail . I got to where I refused to install the things on customers cars the failure rate is so high on those things

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Oh great! I still have the old one sitting in my garage, guess i'll throw it in my tool box.

Just wondering, do all Hayden clutches typically kick in around 210 degrees?

I don't know the history of my fan clutch (it's the same one that was on the truck when I got it in 2001, and it's always acted the same), but it kicks in between 200 and 210 degrees...and my coolant's NEVER gotten warmer than that IIRC most original fan clutches don't kick in until 220 or even 230? I'm just curious...I certainly have no complaints about my fan clutch...

freebird01 said:

yes the fan barely crawls along but if you look at the shape of the blades on that manual compared to an electric your answer is there. the manual fan has a larger surface area and more of a rake to them then an electric setup. thats why it is much louder then then an electric setup as well.

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Hmm... I would take you to task on that and ask you to prove it. I used to think the same thing, until I converted to electric. I studied side by side my electric fan blades and the big metal fan. I agree, at casual observation, the metal fan appears to have more guts, but if you get out a tape measure, and start comparing square inches, my dual Tauras fans have more surface area than the single mechanical fan. The pitch of the blades is higher on the mechanical because it has to be. There are fewer blades. The noise is actually more due to poor design than higher efficiency. Things like pop rivets just randomly drilled in the blade to balance it. I mean... c'mon. That creates a ton of turbulance. Add to that the fact that the factory fan shroud forces more of the air to be concentrated in and around the center, versus my dual electrics that put an even pull on the air across the rad, it all adds up to better design, higher efficiency and superior cooling. Just look... the factory fan, about one third of it was where the bottom tank of the radiator is. Of course, this is the wide non-AC rad. Hopefully this is one of the reasons they got away from this design. I mean.... how stupid. What were they thinking?

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The Warden said:

Just wondering, do all Hayden clutches typically kick in around 210 degrees?

I don't know the history of my fan clutch (it's the same one that was on the truck when I got it in 2001, and it's always acted the same), but it kicks in between 200 and 210 degrees...and my coolant's NEVER gotten warmer than that IIRC most original fan clutches don't kick in until 220 or even 230? I'm just curious...I certainly have no complaints about my fan clutch...

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This is why I was thinking I bought a good one, it kicks in low and keeps this thing always under 210.
Now I'll sit back and see how long the damn thing lasts!

If anyone is interested, there is one Four Seasons fan clutch left at RockAuto for $53 It's part number 36963, use the drop-down box to get the closeout price.

Mine is still the original Ford unit, and it's working -- but at that price I had to get a spare to try out. After a bunch of searching I found where Four Seasons said it engages at 180 degrees F air temperature. If I have some spare time, I'll measure the air temp that both engage and post it here.

There's really no telling exactly what coolant temp is going to equate to 180 F air temperature. If the radiator doesn't transfer heat well to the air, the air won't get hot enough to engage the fan clutch.

Fan clutch test data...

The temperature measured below was from between the radiator and fan using a digital thermometer. RPM was measured with a optical tach. Ambient for both tests was ~67 F.

Ford-Eaton (22 years young):
Full engaged 180 F air with 1550 RPM @ pump and 1505 RPM @ fan
Full disengaged ~115 F air with 1600 RPM @ pump and 405 RPM @ fan
Note that disengagement temp was significantly lower then the newer model. It may actually have a slower reaction time and some delay.

4 Seasons 36963 (the $53 special)
Full engaged 177 F air with 1590 RPM @ pump and 1535 RPM @ fan
Full disengaged 145 F air with 1710 RPM @ pump and 415 RPM @ fan

The standard thermostat starts to open at 192 F and is fully open at 212 F. It seems to me that the air temp that activates the fan clutch varies with air flow, air temp entering the radiator, coolant temperature, and the heat transfer ability of the radiator. For example, if the radiator is corroded and clogged, the air would tend to stay cooler leaving the radiator even though the engine was hotter then normal.

Anyway, for the air leaving the radiator to get to ~180 F, the coolant itself has to be significantly hotter then 180 F. And, as airflow increases, the coolant temperature would have to increase to keep the air temp leaving the radiator at 180 F. 210+ coolant temperature before the clutch fully engages sounds plausible to me. The engineers probably wanted to stage the cooling so that the thermostat was pretty much full open before the fan clutch was full engaged for best fuel economy.

The fan clutch senses air temperature with a bi-metallic spiral element in the front. The outer end is fixed with some RTV in a slot, and the center rotates based on temperature. Re-fastening the outer end of the bi-metallic spiral would shift engagement temperature. The spiral straightens (un-winds) as it heats up, so that's the direction to move it for a lower temperature.

Good info!! Thank you for the experimentation...I wonder if this would be worth writing up and giving to Mel as a tech article?

Agnem said:

Hmm... I would take you to task on that and ask you to prove it. I used to think the same thing, until I converted to electric. I studied side by side my electric fan blades and the big metal fan. I agree, at casual observation, the metal fan appears to have more guts, but if you get out a tape measure, and start comparing square inches, my dual Tauras fans have more surface area than the single mechanical fan. The pitch of the blades is higher on the mechanical because it has to be. There are fewer blades. The noise is actually more due to poor design than higher efficiency. Things like pop rivets just randomly drilled in the blade to balance it. I mean... c'mon. That creates a ton of turbulance. Add to that the fact that the factory fan shroud forces more of the air to be concentrated in and around the center, versus my dual electrics that put an even pull on the air across the rad, it all adds up to better design, higher efficiency and superior cooling. Just look... the factory fan, about one third of it was where the bottom tank of the radiator is. Of course, this is the wide non-AC rad. Hopefully this is one of the reasons they got away from this design. I mean.... how stupid. What were they thinking?

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your just enhancing my point there mel. I never said anything about efficiency or which one is better over the other. I was mearly commenting on the noise of once vs the other. my comments were also strictly observational as i do not have a degree in fluid dynamics lol

that being said i wouldnt mind going to electric fans as well.

when you did your mod to the moostang was it a wide rad like what i got in my truck or the narrow?

I may have already said this a few pages ago, but it can bear repeating if I did.


The little coiled bi-metal thermostat gizmo located in front-center of every non-electrically engaged fan-clutch is situated down in behind the radiator and is usually never seen nor messed with until some major problem requires removing the fan.

After a few years, they get so packed full of greasy-grime that their effectiveness is lost, both from the grime insulating the thermostat against the heat coming through the radiator, and from the grime obstructing proper action of the bi-metal coil.

Whenever one feels that their fan-clutch is no longer doing it's proper job, before spending a bunch of money and time, use a dentist mirror and have a look at the coil; you will most likely find it packed full of crud.

Saturate and clean it well with brake-cleaner or the like and that alone may cure the problem.

MS Tech clutch is $345. Ford clutch is $275. Prices good this week.

I'm thinking of MS clutch, but also considering pinning the Hayden I have. Anyone have trouble with pinned clutch spinning off when you shutdown the engine?

i did this

welded it fast to the nut so i can still get a wrench on the nut. my friend who is a mechanic has a handy tool from off the truck that goes into his air hammer to put them on and off. so nope...mine aint commin off lol.

those tabs are 3/16" material.