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Fan Clutch time

Pillow

Pillow

Recruit
Messages
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Location
Warrenton, VA
What is the best fan clutch out there these days?

This for a 4 bolt setup and I already have the later 8 blade metal fan. Really I would like to just get a clutch...

Some of the Severe Duty ads are claiming that you need 180F thermostats - which is not acceptable IMO.

Anyway it seems that most of the vendors are claiming awesomeness in their "proprietary" Severe Duty setups or want you to use a Duramax fan. What is the truth???

Thanks!
 
Did you notice that is locked up 15 degrees earlier?

JK is a straight shooter and I like that he recommends reasonable changes w/o the hype. He has had unpopular thoughts in the past which seems to be proving true in the long run as well! But I will not go down that path at the moment.
 
I'm not sure. My engine is louder than most - there's no way I can hear the fan running. I suppose I could wire in a light, but it works well enough that I haven't worried about it. I agree with your statement, too - I like that he's upfront about things.
 
I ran the Kennedy clutch and still do. It will keep you below or at the 210 mark. Some claim the fan doesn't kick out. I ran the single T-stat at 180 and with the lower fan clutch and thus lowered the entire temp curve. The problem is getting the fan on when you hit a hill as things heat up WOT without the fan on. T-stats have to open, radiator gets hot, then the air gets hot and heats up the fan clutch thermal spring. Then the spring moves and you wait for the working fluid to move in the clutch and finally the clutch locks up. This delay can take you from 180 to 215 easy. Higher temp clutches and t-stats just push the start and stop temps higher like 195 to 225 figuring/guessing a 30 degree rise.

As above the fan does it's job and then kicks out. The Duramax fan pulls more air at idle useful for AC. The 20" steel fan will do the job just as well when moving as that is what I ran pulling hot, hard, and heavy. Change fans if you need more AC performance IMO. (6 Blade fans are junk in all cases for this body style!)

So if the fan doesn't unlock to your liking I suggest you make sure the radiators are clean by pulling the oil cooler off and cleaning, then go with a 180 T-stat. When you are pulling/towing the T-stats are usually open and no longer a factor. The fan is regulating the temps.

With your removal of the GMx turbo you should have less fan activity as I noticed with the ATT on my 6.5's.
 
I went with a rockauto acdelco fan clutch and the big thing that mattered was the mod to the spring length so it engages earlier. Towing it kicks in when needed just above 200, roars like crazy, brings the needle right down and kicks out. That's towing at 16500Lb combination weight. A fresh fan clutch with the mod and a good fan, clean rad/condenser fins is all you need in my opinion. No need for the severe duty which kicks in at 170 and will never kick out hurting MPG.
 
Pillow said:
What is the best fan clutch out there these days?

This for a 4 bolt setup and I already have the later 8 blade metal fan. Really I would like to just get a clutch...

Some of the Severe Duty ads are claiming that you need 180F thermostats - which is not acceptable IMO.

Anyway it seems that most of the vendors are claiming awesomeness in their "proprietary" Severe Duty setups or want you to use a Duramax fan. What is the truth???

Thanks!
Click to expand...
How did you get an 8 blade fan? I took out my 9 blade metal fan and put in a 9 blade dmax fan since it has less rotational mass. I have the stock fan clutch but were I to get a new clutch fan setup I would go Hayden severe duty. http://www.amazon.com/Hayden-Automotive-2839-Premium-Clutch/dp/B000C3DD5O/ref=au_pf_ss_2?ie=UTF8&Model=K3500|461&n=15684181&s=automotive&Make=GMC|48&Year=1998|1998&carId=001 OR http://www.partsgeek.com/hthp9x2-chevrolet-tahoe-fan-clutch.html?utm_source=nextag&utm_medium=pf&utm_content=mcs&utm_campaign=PartsGeek+Nextag&fp=pp&utm_term=2839+Hayden+Fan+Clutch
 
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Edzzed said:
How did you get an 8 blade fan? I took out my 9 blade metal fan and put in a 9 blade dmax fan since it has less rotational mass. I have the stock fan clutch but were I to get a new clutch fan setup I would go Hayden severe duty. http://www.amazon.com/Hayden-Automotive-2839-Premium-Clutch/dp/B000C3DD5O/ref=au_pf_ss_2?ie=UTF8&Model=K3500|461&n=15684181&s=automotive&Make=GMC|48&Year=1998|1998&carId=001 OR http://www.partsgeek.com/hthp9x2-chevrolet-tahoe-fan-clutch.html?utm_source=nextag&utm_medium=pf&utm_content=mcs&utm_campaign=PartsGeek+Nextag&fp=pp&utm_term=2839+Hayden+Fan+Clutch
Click to expand...


Info from Hayden for my year 6.5 fan clutch;
"HAYDEN Part # 2850 Thermal
Reverse Rotation Severe Duty Thermal Fan Clutch
Engages at about 170° radiator air temperature, (about 30° lower than coolant temperature)."


Are you sure you would want this fan clutch? It will never kick out empty never mind towing a great Spartan, ask me how I know.

Don't do it... get a fresh stock one and do the spring mod so it kicks in at 200 or where ever you want it to.
That is the way to go!
 
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Thats the wrong number.......Severe Duty doesn't mean it engauges earlier......It spins at a greater % shaft speed.

Use the search and find the correct # should be something like 2839 or 2389........You"ll find many threads, search, "Imperial Hayden fan clutch"
 
Brooklyn Tow said:
Thats the wrong number.......Severe Duty doesn't mean it engauges earlier......It spins at a greater % shaft speed.

Use the search and find the correct # should be something like 2839 or 2389........You"ll find many threads, search, "Imperial Hayden fan clutch"
Click to expand...

the two links I posted are both 2839. Alexe, you said to ask "how you know" OK, I'm asking. the 2850 is for a dmax according to http://www.summitracing.com/parts/HDA-2850/ Ed
 
Edzzed said:
the two links I posted are both 2839. Alexe, you said to ask "how you know" OK, I'm asking. the 2850 is for a dmax according to http://www.summitracing.com/parts/HDA-2850/ Ed
Click to expand...

That is not the wrong number for my application. I have a year 2000 with the spin on fan clutch not the 4 bolt, that number is correct for my 6.5. But part number does not matter, Hayden Severe Duty is what matters here and here is the difference from the standard Hayden or any brand std. duty in Haydens own words. For their severe duty they say this, "Engages at about 170° radiator air temperature, (about 30° lower than coolant temperature)."
Those are their words not mine.
I do agree and how do I know (glad you asked Ed). I put a Hayden Severe Duty on another truck I have and it is always engaged. The only time it cuts out and stops making a lot of noise is when I go on a long downhill off the gas and it's cool out. Big mistake putting that on, always engaged means less mpg.
With the standard new fan clutch on my 6.5 van with the spring mod it does not reach 210 towing 16500 pounds on a hot day uphill yet it cuts out and is quiet towing on the flat roads.
Brooklyn Tow, severe duty does engage earlier probably locks up tighter too but my towing hot was cured with a fresh std.fan clutch & spring mod. We should get together for a Brooklyn Lager & 6.5 talk! I'm not far down the street.
 
Edit: I have a 9 blade 20" steel fan stock from 99. Not 8 blade. My bad.


I see where Alexe is going with this idea. From the Hayden website, I agree that a 170 degree radiator temp might be just right. -30 from the coolant temp would be 200 degrees which is about when we would want the fan to kick in. Any earlier and the fan would never kick out! Maybe this is why on the -15 cooler fans that others offer they recommend 180F thermostats so the fan kicks out!

In theory though, the severe duty should have kicked out on Alexe's other truck... Hmmm.

http://www.haydenauto.com/Featured Products-Fan Clutches and Fan Blades/Content.aspx
 
I recently installed the Hayden Severe duty 2839. With the Dmax plastic fan my coolant temp never gets over 200 towing a 10000 TT.
 
A couple of thoughts. From what I hear on this forum a 195 thermostat will give a couple, three more mpg's compared to a 180 degree so that's a big consideration at these fuel prices. Also, hayden saying the radiator temp will be 30 degrees cooler that the coolant temp I believe is very optimistic unless you are in cool weather. I ran tests on my radiator with my brothers fancy laser thermometer no touch tool and the 4 core radiator in other truck (w/the hayden severe duty) sure ain't 30 degrees cooler than the coolant. All's I'm saying here is be careful you don't get a set up that never kicks out like me. Your mpgs will suffer never mind the noise. My wife asks what is wrong with this engine? I tell her it's just the engaged fan.
For my 6.5 the fan clutch mod is the ultimate and I tow heavy (16500) only a few times a year. I don't know how that guy on another thread here can tow 26500 with a 6.5!
 
Have a Haden in my 7.3 PSD and recognize that it is not the exact same part, but experience is that the clutch locks up for the first three miles after a cold start and ~1 mile after a warm start where the OEM would only come on for maybe 1/2 mile after start. Mileage did not seem to show a difference though.

Just going to put this one out there . . . If money is not too much of an issue, am seeing where the Horton keep temps tightly in control as it reacts to coolant temp not air temp, but it does come with some conversion items (pressure switch and pusher fan for the A/C) and I only know of one person whom admits to making it work. The Horton is in my upgrade plans for the Burb, so I will make the population two when I get there. Added benefit to the Horton (ignoring cost) is that it freewheels when off, so the engine gets the benefits of an electric fan setup.
 
Edzzed said:
How new or clean is your radiator as that will have an effect as well. Do you have any issues with the fan not disengaging ?
Click to expand...

The cooling stack was cleaned very well the same time I put this clutch on (about 2 weeks ago). I have logged a few hundred towing miles since then though. I can not tell you about when it disengages though as the only time my temps ever start to get warmer than 195 is towing up a hill and I can't hear the fan over the other noises that go along with a 18 year old truck. :)
 
I am only stating my experience in 32 -121 degree weather with the KD fan clutch. It should work fine with a 195 t - stat as I explain below. I used it with a 180 T-Stat and found that it runs sooner and keep peak temps down to the 215 max. It also kicks out just fine. On heavy loads it acts like it comes on 100% quickly.

Your AC condenser can run at 160 degrees, look at the pressure in it running and convert the R134A temp at that pressure. More airflow means it runs cooler with lower high side pressure. Then you add coolant temp to the mix from the radiator. The air coming off the radiator is not ECT as the radiator has cooled some and the air hasn't warmed up 100%. How close to ECT the air gets is dependent on radiator thickness, airflow, etc.

Your engine will be at 180 degrees when the 180 T-Stat starts to open and 190 at full open. 195 t-stats are 195 to 205 full open.

So the fan locks in at 170 degrees and cools things down.

The 195 degree thermostat closes at 195.

Question:
What happens to the radiator temperature when the thermostat closes?

Answer:
It cools down, the air temp coming off it drops and the fan continues to run as the thermal clutch spring moves to turn the fan off. After a delay while things move in the clutch the fan clutch finally kicks out. So a 170 degree kick in fan clutch will kick out when the engine thermostat closes because the radiator cools down.

There is such a thing as too cool. This is where things need to be hotter and the airflow from moving could cool it without a fan. Or there is enough heat to keep the fan on from poor airflow or high load even with the fan running.

The Horton fan clutch system will eliminate the delay of kicking on a fan with sudden WOT mountain climbing. It is an on/off fan and would drive you nuts with "slam -roar - thud - silence" vs. the gradual fan that may not need 100% lockup. (EV fans are the best of both worlds.) However for heavy loads it is a good choice as the factory style fan clutch is going full lockup but is late to the party.
Electric fans for AC do not move enough air alone and become a restriction to the mechanical fan. The Horton would need an AC pressure or condenser temperature switch to turn on. An aux cooling fan could reduce the Horton run time for AC, but not eliminate it in more extreme hot/humid weather.
 
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