Early 1FZ Fan Clutch (Black/Blue Hub)

[80t0ylc]

This thread is started in an attempt to separate old fan clutch questions from Landtank's Blue Fan Clutch thread which discusses and instructs how to set up the new part Toyota replacement fan clutch. For first timers to this thread, this is an attempt to discuss the possibility of revamping your OEM black hub or blue hub clutch, instead of replacing with the new blue Toyota replacement clutch. If you are having fan clutch related issues, browse through this thread to help you make a decision which route to go - revamp or replace with a new clutch.

Reference Landtank's thread for more info

This 1st question can probably best be answer by Kevin (Tools R Us). I could have PMd him, but I thought his experience on these fan clutches would best be shared amongst all of us.

I pulled my fan clutch to verify the type and condition due to my '94's mileage and also recent cooling system work that I've been doing. I've included a couple of pics. I started brushing off the dirt around the thermostat/spring and than thought, maybe before cleaning it up, I should ask about what looks to me to be a possible leak of fluid starting. The top-most fan mounting screw in the pics has an accumulation of greasy dirt. Is this an indication of a leak starting? The bearing appears to still be in excellent shape, at least by feel. I'm going to continue cleaning it up and remove the fan. I can include more pics if needed. Thanks for any light you can shed on this!

 

[80t0ylc]

In cleanup and after fan removal, several Phillips head screws appeared to have small amounts of greasy dust on them. Not a whole lot and it easily cleaned up with an old tooth brush. I'm pretty much decided to crack the clutch open and replace the fluid. I'm going to try the 10k due to the climate here and research I've done. I've heard that over filling would cause constant lock up. How much fluid should I be putting in?

 

[Tools R Us]

From what I can see, wouldn't worry about that seepage, they almost always seep a bit around the spring. As long as it's not getting goo all over the fan blades, I run them. My normal fill for these is ~50ml, adjusted for how well it was drained.

 

[80t0ylc]

From what I can see, wouldn't worry about that seepage, they almost always seep a bit around the spring. As long as it's not getting goo all over the fan blades, I run them. My normal fill for these is ~50ml, adjusted for how well it was drained.

Thanks!

 

[cool breeze]

dont forget to adjust the temperature at which it opens like landtanks thread

 

[80t0ylc]

dont forget to adjust the temperature at which it opens like landtanks thread

It was my understanding that the early fan clutches were not adjustable. I could be mistaken, though.

 

[Tools R Us]

It was my understanding that the early fan clutches were not adjustable. I could be mistaken, though.

That one is adjustable, but I wouldn't adjust it, upgrade the fluid and enjoy the new found performance.

 

[cool breeze]

why not? i have adjusted two succefully, well i think it was successful. been on the truck for more than a year and with the modded temp gauge cools quite well.

 

[80t0ylc]

Well, first things first. I'm going to try and find fluid today. Then I'll open it up to drain it. The clutch has performed flawlessly and I don't want to fix something that ain't broke. I'm just trying to stay ahead of the game. With 222K miles on the clock, it was necessary to replace the OEM t-stat earlier this week. And I'm thinking - what can I do to help prevent my fan clutch from dying on a trip or out on the trail?

So when it's open, what temp should I be looking for it to activate? Josh, why would I want to adjust the temp if it's performing right for me now? I like Kevin's advice to just replace fluid and go. But, I'll listen to your ideas and consider them. Thanks for the inputs, guys!

 

[Tools R Us]

why not? i have adjusted two succefully, well i think it was successful. been on the truck for more than a year and with the modded temp gauge cools quite well.

The quick easy answer is: IIRC this is the original clutch from his rig, so over the last ~16yrs it has well proven that it's set correctly to properly control the temp in his rig. Over that time the fluid has degraded, simply upgrading the fluid will make it preform correctly for years to come.

I don't have time to type the long answer right now, maybe later. It works, but there is a pretty big disadvantage to adjusting them cooler.

 

[80t0ylc]

It figures! The one and only local hobby store only carries 900 CST max. Their specs show it to be 100% silicone, so I had the guy order me a 60ml bottle of the 10K and it should be in around mid-March. 1 other place I can call that's 60 miles south of me after lunch. If they have it, I'll try 8K and rely on the 10K as a backup or in case the 8K is too light. Glad I haven't started draining my clutch yet - might have to put it back in as is.

 

[cool breeze]

My support is anecdotal; original black hub fan clutch, fluid and all...170k

All i did was take the information that Rick had put forth in his thread about adjusting the clutch's timing to open a little sooner like the blue hubs. I could not find 10k cst oil readily so i went with straight 7k which would be a large improvement from the factory 3k cst 19yr old oil.

This was done about a year and 10k miles ago, trucks been through the desert of west tx, colorado rockies, and idling for hours off-road during central tx summer of 100 degrees @ 80%+ humidity. I have no pusher fan, only the fan clutch with a modded temp gauge and temp never reaches the red. It did get close driving to El Paso in the dead of summer day with AC blasting but not into the red.

One thing i do feel is lacking is the AC temps, in the dead of summer the ac seems just not able to keep up even fully charged and running correctly...could it be the clutch even if coolant temps are good?

 

[80t0ylc]

Josh, if your engine temp per your temp gauge is good, but AC output is not cold enough, sounds like something with AC. You said it's fully charged, but is your evaporator maybe choked with dust or debri? That's under the dash passenger side, the coils that cool the air. Doesn't sound like fluid for your clutch is causing this, but Kevin (Tools R Us) is the guru for these clutches. He lives down near Phoenix, AZ. So he's well aquainted with high temps, AC and fan clutch performance. PM him if he doesn't chime in soon. I see you've got a '94, also. Is that the rig with the problem? If so it would was 16 yr old original clutch fluid, right? BTW, thanks for posting. My 10K fluid is still not in. You've reminded me to check on it!

 

[Tools R Us]

OK, the long answer, I have posted this info before, probably in the huge thread and fragmented, so will attempt to better explain it here. This info is a collaboration of several local users who have worked to get the best setup/performance from the clutches. My rig has run with temp sensors (grill intake air, fan output, water and A/C vent), for ~ a year out of the last 4 years, to attempt to get a feel for what is happening.

The clutches are made with 3 ranges of “on”, (on some the center step is progressive, but will use the 3 step, easier to explain), these ranges match well with fan demand, depending on load. The clutch uses cooler output air temp to control fan speed/power, IMHO this is a great method, it accurately senses loads, A/C cycles, motor loads, ambient temp, etc. The clutch thermostat is very active and quickly acts to changing loads.

The steps are not linearly progressive, the first is pretty wimpy, second somewhat stronger and the third a big step. If I had to make a guess, based on optical tach and fan laws, it would look something like this; first step 1250cfm, second step 2500cfm and third 5000cfm. These numbers are guess, the real number will very depending on viscosity, flow restriction, etc, but the ratio among the steps is close.

There are 3 main fan load need ranges, it’s almost like someone designed the clutch to work with them! First light load cruising, a little fan is needed, but not much. Second, heavy load cruising, climbing hills, hot weather with heavy A/C loads, towing, wheeling, etc. Third is stopped, idling, this is by far the most demanding, especially when hot with A/C load. The rig is stopped, so no airflow over it and the motor is at idle, so low shaft speed, the third step is mostly reserved for this and is why it’s stronger than the rest. Without this strong step, under hood airflow drops, heat soak increases, A/C vent temp raises and possibly raises the A/C high side pressure enough to cycle it off in very hot weather.

If you adjust the valve down, say 25F and use close to stock viscosity fluid, you have basically moved each step down a range. The first step is wasted, the fan runs almost all of the time and before it’s needed. The second step runs in the temp range where the first step would normally run, you gain some performance due to the bigger valve opening. The third runs in the temp range where the second step would normally run, you also gain performance due to the much bigger valve opening. At idle your still running in the third step, so gain nothing, idle heat soak will be high and A/C performance low, will start thinking about band-aids like cutting holes in the hood, electric fans, etc. In my observation this is like changing to a cooler coolant thermostat, it starts cooling sooner than needed, but adds nothing to total cooling capacity.

Our observation is that no fan is needed below about the 120F range at cooler output/clutch thermostat and about this setting matches well with the third step working only at idle/rig stopped. By stepping up the fluid viscosity, clutch performance is increased at each step, they work at the intended temps and total cooling capacity is increased, depending on the fluid viscosity dramatically increased.

Locally we have done dozens of clutches, adjusted the valves both hotter and cooler, run fluid from 6K to now a couple running 30K, played with electric fans, hoods, etc. Have directly compared them on the highway and trail and found changing the viscosity and leaving the valve alone is the best setup for overall performance. Once we figured this out some of the electric fans are abandoned in place or in the case of mine sold. Again this is our observations from years of playing with them in desert climate, so your mileage may vary.

 

[S.CarolinaFZJ80]

OK, the long answer, I have posted this info before, probably in the huge thread and fragmented, so will attempt to better explain it here. This info is a collaboration of several local users who have worked to get the best setup/performance from the clutches. My rig has run with temp sensors (grill intake air, fan output, water and A/C vent), for ~ a year out of the last 4 years, to attempt to get a feel for what is happening.

The clutches are made with 3 ranges of “on”, (on some the center step is progressive, but will use the 3 step, easier to explain), these ranges match well with fan demand, depending on load. The clutch uses cooler output air temp to control fan speed/power, IMHO this is a great method, it accurately senses loads, A/C cycles, motor loads, ambient temp, etc. The clutch thermostat is very active and quickly acts to changing loads.

The steps are not linearly progressive, the first is pretty wimpy, second somewhat stronger and the third a big step. If I had to make a guess, based on optical tach and fan laws, it would look something like this; first step 1250cfm, second step 2500cfm and third 5000cfm. These numbers are guess, the real number will very depending on viscosity, flow restriction, etc, but the ratio among the steps is close.

There are 3 main fan load need ranges, it’s almost like someone designed the clutch to work with them! First light load cruising, a little fan is needed, but not much. Second, heavy load cruising, climbing hills, hot weather with heavy A/C loads, towing, wheeling, etc. Third is stopped, idling, this is by far the most demanding, especially when hot with A/C load. The rig is stopped, so no airflow over it and the motor is at idle, so low shaft speed, the third step is mostly reserved for this and is why it’s stronger than the rest. Without this strong step, under hood airflow drops, heat soak increases, A/C vent temp raises and possibly raises the A/C high side pressure enough to cycle it off in very hot weather.

If you adjust the valve down, say 25F and use close to stock viscosity fluid, you have basically moved each step down a range. The first step is wasted, the fan runs almost all of the time and before it’s needed. The second step runs in the temp range where the first step would normally run, you gain some performance due to the bigger valve opening. The third runs in the temp range where the second step would normally run, you also gain performance due to the much bigger valve opening. At idle your still running in the third step, so gain nothing, idle heat soak will be high and A/C performance low, will start thinking about band-aids like cutting holes in the hood, electric fans, etc. In my observation this is like changing to a cooler coolant thermostat, it starts cooling sooner than needed, but adds nothing to total cooling capacity.

Our observation is that no fan is needed below about the 120F range at cooler output/clutch thermostat and about this setting matches well with the third step working only at idle/rig stopped. By stepping up the fluid viscosity, clutch performance is increased at each step, they work at the intended temps and total cooling capacity is increased, depending on the fluid viscosity dramatically increased.

Locally we have done dozens of clutches, adjusted the valves both hotter and cooler, run fluid from 6K to now a couple running 30K, played with electric fans, hoods, etc. Have directly compared them on the highway and trail and found changing the viscosity and leaving the valve alone is the best setup for overall performance. Once we figured this out some of the electric fans are abandoned in place or in the case of mine sold. Again this is our observations from years of playing with them in desert climate, so your mileage may vary.

It figures you should post this now after I just put 10k fluid in my blue hub and adjusted the thermostat to open at 95 degrees F.

Oh well. I hope it works for me.

On thing that I did notice is that the hub, when filled with 10K & according to Landtanks thread, is very hard to rotate versus the old worn out black hun that was removed. Is that due to the new fluid kind of like a new bearing vs. an old one?

Any thoughts on that?

 

[Tools R Us]

It figures you should post this now after I just put 10k fluid in my blue hub and adjusted the thermostat to open at 95 degrees F.

Oh well. I hope it works for me.

You should be OK with the late blue hub. They are wimpy compared to the earlier clutches, so require higher viscosity to achieve equal performance. This thread is mainly about the earlier clutches, they are more powerful, especially in the third step, so running third step at cruise speeds can overpower the belts.

On thing that I did notice is that the hub, when filled with 10K & according to Landtanks thread, is very hard to rotate versus the old worn out black hun that was removed. Is that due to the new fluid kind of like a new bearing vs. an old one?

Any thoughts on that?

The higher viscosity fluid causes more drive, will feel more stiff, this is normal, what you are looking for.

If you have a build able black hub Aisin, why would you move to the late blue? I have yet to see an late blue hub that will out perform an early, the early clutches kick azz!

 

[cool breeze]

Well there it is, long version makes more sense than the short...thank you for taking the time to explain fully so we can all understand what's happening and not blowing a bunch of hot air..ha.

So now to re-adjust mine from 95* back to..... what average temps did you see them normally start to open at? 120f ?
If they're similar to the blue hubs then there was quite a large range at what they were set from the factory.

While im in there would there be a nice gain to move up from the 7k csT in there now?

 

[FirstToy]

I found my old clutch so I decided to open it. It doesn't say AISIN or anything Toyota. No markings on the outside of any kind. It was held together by 4 torx m25 bolts.
Is this one worth keeping or should I mess with the blue clutch instead?

to open the front half slots, twist the coil

all the fluid came out of here, poured out pretty quickly

the orangey fluid is what came out of the front half, the little dab i'm pointing to is what came out of the back half.

I have 10K and 7K fluid. I think I'll try the 10K and see what happens.

Is the fluid orange from old age/breakdown or is that just the color it came?
I don't know if it broke down, the viscosity seems similar to the 7k fluid but that's just looking and seeing how fast it runs down the bowl.

 

[cool breeze]

Its definitely NOT the oem black hub we are discussing now...maybe an aftermarket installed somewhere in the past. As from what ive seen i would have gone 10k from the get go but 7k has been serving me fine in my climate...doesn't say where you are?

 

[Cruiserdrew]

James-What you have is an Eaton clutch, I think. The later trucks got that, probably to increase US content (kind of like the Timkin wheel bearings). It's a good clutch and if you replace the fluid, likely good for another 100k miles. I have one of those too, and recently swapped the fluid and tossed it in my on board spares. The Torx screws are a dead give-away.