I'll definitely being doing the clutch mod, so count me in. Anyone know of a hobby shop up in the north part of the Valley? I'd be happy to pick up some fluid.
Ed
Ed
Creeping Temps
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ok...here's a general question.
If a fan clutch is designed to allow the fan to spin at a percentage of the speed of the shaft then what would be the downside of eliminating the clutch all together (my old 442 didn't have one)? You would add a spacer and the fan would spin at 100% of the shaft. Max with a clutch = about 85%-90%. I could see an issue in the very cold regions. Another benifit would be less rotating mass on the water pump shaft.
If a fan clutch is designed to allow the fan to spin at a percentage of the speed of the shaft then what would be the downside of eliminating the clutch all together (my old 442 didn't have one)? You would add a spacer and the fan would spin at 100% of the shaft. Max with a clutch = about 85%-90%. I could see an issue in the very cold regions. Another benifit would be less rotating mass on the water pump shaft.
Howdy! Fan clutches were developed 20-odd years ago for several reasons. At hiway speeds, there is often enough air flow that the fan is rendered useless. If the fan does not spin up to speed when the engine is cold, then it will warm faster. Less rotating mass MIGHT improve gas mileage. The fan is quieter when it doesn't spin so fast all the time. Fixed (solid mount) fans work just fine. They were the standard for many years. I have seen fan clutches converted to fixed fans when they were not working properly. This was done by running a couple of sheet metal screws thru them and jamming the bearings. Obviously, this is not repairable, but it is an option for an overheating engine. John
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The clutch is thermostat controlled, allowing the fan to freewheel when not needed, making it a little more efficient. The clutch systems are designed for them, the water pump shaft is driven faster. The fan is designed for the clutch speed and if driven at shaft speed there is a big risk of it coming apart at speed, that never ends well, think holes in the hood, radiator, etc. The fluid coupling clutch has some slip, a good thing for offroad, damage can be less if it hits something. In a water crossing the moisture will cool the thermostat allowing the fan to freewheel, greatly reducing the chance if damage.
The option for direct drive is a flex fan, I'm not a big fan of them, seen way too many have failures. Their not tunable, so you have to hope that the one that you buy has the capacity to pull the max flow needed in a stress load situation, and it's driven that way all of the time, 95% of the time not needed. By driving it at 100% all of the time you reduce efficiency and increase load on the motor and wear on the water pump bearing, belts, etc. Any fan driven at shaft speed is much more sensitive to balance issues, a small imbalance will cause big shaft vibration, bearing damage, possible fan destruction. The faster a fan is driven the higher the chance of it coming apart. Metal flex fans cause the best carnage, nice high speed metal knifes that make short work of hoses, battery, radiator, hood, etc.
IMHO the clutch is the way to go, especially the stock Toyota, it's refillable. The thermostat works to keep the radiator output airflow temp the same. Lets say it tries to keep it at 150F, when it's 85F outside it doesn't require much airflow to to make that. Now it's 110F+ and your sitting in traffic, on blacktop, with a bunch of traffic all with their A/C on, the input airflow at the grill is 130F+ it takes a ton of airflow to make 150F at output.
My observation is, in the AZ traffic with the stock fluid, the airflow output temp keeps climbing. The thermostat is opening more and more but the fluid cant deliver the torque needed to the fan, so the thermostat winds up wide open and the clutch still not pumping the air needed. On my junk it never overheated, but the A/C would heat soak and deliver high vent temp, the coolant temp gauge would climb.
With the thicker fluid in this scenario, the output airflow temps climb, quickly stabilize, then drop back to the base temp. Telling me that the thermostat valve is opening, the fluid clutch is delivering good torque to the fan, doing it's job. In other desert parts of the world the thin fluid we get isn't even available, their clutches come filled with and the replacement fluid is all the thick stuff. In most of the US 90F is a hot day so our stuff is tuned for that.
Yes, I drove around with temp sensors taped all over the truck most of last summer, what a geek!
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Be very careful with motor rpm if you do this! I was a tech during the time when fan clutches were new, some of the "old school" techs thought this was the way to "fix" them. They learned the hard way that the pulley ratio is different on clutched setups, the shaft, water pumps run faster and the fan's rated constant running rpm is lower than shaft speed. Some survived others came apart with predictable results.
The best were the guys that thought "my old heavy, steel, direct fan has worked great for years" and pulled the clutch, got an adapter and bolted that bad boy on. The carnage was awesome, hoses, radiator cut, blades embedded in battery's, ejected out through the hood, etc! Them were the good days!
Fans are too often overlooked, they aren't lifetime parts, need to be inspected. The way Toyota makes them is good, the translucent plastic shows stress well. When inspecting look for bright white lines, especially at the blade roots, this shows that the blade(s) have been stressed and may fail. They can and have failed in normal use, the stresses on them are high. The most common in the Toyota world is the early 3.slow ring fan, the outer ring is heavy leading to early failure, there is a newer non ring fan available for them.
Howdy! Granted, it is a temporary fix, but if you have a bad, non-refillable clutch, it will get you home, so to speak. Just drive easy and don't rev the engine like Parnelli Jones.
I think the newer plastic clutched fans are designed to perform efficiently at lower rpm to offset the noise, drag, and balance problems. They are also lighter and cheaper to make. I know that a lot of them used to have an outer ring connecting to blade tips
Conversely, in the good old days of mechanically driven steel fans, large commercial grade trucks had larger fans with larger drive pulleys and smaller water pump pulleys to spin them at higher speeds. These setups normally had small carbs and low-rpm cams, so that they rarely ran over about 4000 rpm. As I have no room for a clutch fan, I am running one of these "truck pulley" setups. I can live with the extra noise it makes, and it does a great job of keeping the engine cool. I haven't even built a shroud for it yet, and it stay cool in the 115 degree weather. I did use a quality fan that is rated at over 9000 rpm, and mine will rarely, if ever, see half of that. John
I think the newer plastic clutched fans are designed to perform efficiently at lower rpm to offset the noise, drag, and balance problems. They are also lighter and cheaper to make. I know that a lot of them used to have an outer ring connecting to blade tips
Conversely, in the good old days of mechanically driven steel fans, large commercial grade trucks had larger fans with larger drive pulleys and smaller water pump pulleys to spin them at higher speeds. These setups normally had small carbs and low-rpm cams, so that they rarely ran over about 4000 rpm. As I have no room for a clutch fan, I am running one of these "truck pulley" setups. I can live with the extra noise it makes, and it does a great job of keeping the engine cool. I haven't even built a shroud for it yet, and it stay cool in the 115 degree weather. I did use a quality fan that is rated at over 9000 rpm, and mine will rarely, if ever, see half of that. John
Steve posted this in the official wrenching thread.
https://forum.ih8mud.com/showpost.php?p=2341824&postcount=48
Advice...
Yup, noticed mine getting warm after highway driving then idling in the Taco Bell line. A/C started blowing warm (116 degrees outside) but truck never overheated. Once I got back up to speed, cooled off again. (Kept the chalupa warm..) Been reading the attached temperature related threads. I am a big OEM fan but appears maybe the Hayden HD clutch may be a viable/improvement ?! Ive also learned through experience (verifying what was said earlier in this thread) that even a 50/50 mix or more towards the coolant side will run warm. I had a truck before where I made it more of a 60% water/ 40% coolant in the summertime and it made the difference in running hot vs. normal temps. Was amazed at the difference (arent we all taught 50/50 from birth?) I dont think the engineers were natives of AZ...;p. In any case, any thoughts on going for a fan clutch repalcement on my 96 80 series w/ 101k miles w/ OEM or Hayden? I dont seem to have a pressing problem but with the motor supercharged (rumor of making it run warmer than non-SC) and heading up north next weekend pulling a trailer and a 80 full of wife & daughters, I'd rather spend a couple bucks and help my odds in keeping a fun trip fun and minimize the whining/nagging potential. At that point, the $$ for a new fan clutch on an 11 yr old rig would of seemed a no brainer.....Advice?
Yup, noticed mine getting warm after highway driving then idling in the Taco Bell line. A/C started blowing warm (116 degrees outside) but truck never overheated. Once I got back up to speed, cooled off again. (Kept the chalupa warm..) Been reading the attached temperature related threads. I am a big OEM fan but appears maybe the Hayden HD clutch may be a viable/improvement ?! Ive also learned through experience (verifying what was said earlier in this thread) that even a 50/50 mix or more towards the coolant side will run warm. I had a truck before where I made it more of a 60% water/ 40% coolant in the summertime and it made the difference in running hot vs. normal temps. Was amazed at the difference (arent we all taught 50/50 from birth?) I dont think the engineers were natives of AZ...;p. In any case, any thoughts on going for a fan clutch repalcement on my 96 80 series w/ 101k miles w/ OEM or Hayden? I dont seem to have a pressing problem but with the motor supercharged (rumor of making it run warmer than non-SC) and heading up north next weekend pulling a trailer and a 80 full of wife & daughters, I'd rather spend a couple bucks and help my odds in keeping a fun trip fun and minimize the whining/nagging potential
. At that point, the $$ for a new fan clutch on an 11 yr old rig would of seemed a no brainer.....Advice?
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At one time Hayden made a nice "full size" HD replacement, now their "HD" is a small thing.
I wouldn't trust it. The blue hub from Toyota is the nicest clutch I have seen and priced right, the only one that I would put on an 80.
The S/C motors really don't like AZ, it's critical to have the cooling system working as well as possible on them. The ring fan doesn't pull near the needed air, some have replaced it with the nonring with better results.
Pure water cools better than any antifreeze mix. Even if you never operate it in freezing temps, some antifreeze is needed for corrosion protection, most agree 20% provides it. I run about 30% antifreeze, that allows for a couple of water top offs and still have protection. There are also products like water wetter that claim better cooling and corrosion protection without antifreeze.
Have a talk with cruiserdan, he has run a S/C for years and has done a bunch of work on it. IIRC he runs a nonring fan and blue hub clutch with 10,000 fluid. Also a great source for OEM parts.
I wouldn't trust it. The blue hub from Toyota is the nicest clutch I have seen and priced right, the only one that I would put on an 80.The S/C motors really don't like AZ, it's critical to have the cooling system working as well as possible on them. The ring fan doesn't pull near the needed air, some have replaced it with the nonring with better results.
Pure water cools better than any antifreeze mix. Even if you never operate it in freezing temps, some antifreeze is needed for corrosion protection, most agree 20% provides it. I run about 30% antifreeze, that allows for a couple of water top offs and still have protection. There are also products like water wetter that claim better cooling and corrosion protection without antifreeze.
Have a talk with cruiserdan, he has run a S/C for years and has done a bunch of work on it. IIRC he runs a nonring fan and blue hub clutch with 10,000 fluid. Also a great source for OEM parts.
got the blue hub today - goes on tomorrow. 40/60 coolant mix. new rad cap. towing up north this weekend, Ill let you know!