Finding a crack in my radiator that only appeared under pressure and caused my truck getting hot has lead me down a bit of a rabbit hole. In looking up things related to the cooling system I found that a bunch of the 80 and 100 series guys (especially in hot and humid areas) are opening up their fan clutches and replacing/adding various volumes and viscosities of silicone fluid to make the clutch lock up sooner and keep temps down and have seen as much as a 20°F drop in ECT from 200-210°T+ (with the AC on in drive at idle) to 180-190°F. I've kinda noticed the same thing on the 95°F+ days that the truck can smell a bit warm when sitting in a drive through for example with the AC on. This also applies when wheeling where leaving the AC on on the trails is super nice. East coast wheeling is a lot of crawling so this is very appealing.
On to my point, has anyone ever rebuilt the Asin FCT-075GX470 fan clutch and replaced or added silicone oil to make it lockup better?
For some context many of the 80 and 100 series guys have done this but basically all of them use the "blue hub" version which are an Asin FCT-004 for the 80 and an Asin FCT-021 for the 100. On the 100 though the FCT-021 is only the factory fan clutch from 98-05. I've seen that either of these models can have their activation temperature adjusted and 95°F is what landtank sells theirs at for the 80 series. On the 100 I've read that people adjusted them between 95-110°F. Halfway through 2005, the 100 clutch goes to the Asin FCT-075 which is the same one thats used in the GX470 and there is no info about these but I'm pretty certain that they are non-adjustable. I did find that the FCT-021 is thinner than the FCT-075 so I'm not sure if this would work on a 470 anyway. It also seems like the fans were different in the 100s that used the newer model fan clutch so the stock fan might not bolt in correctly on the GX or be too far out of the fan shroud.
As far as fluid, the stock fluid in the blue hub clutches is 3-5k depending on the model number and more weight and/or more fluid means more drag and thus more lockup. In the earlier portions of the thread many people were saying they were running 7-9k fluid but as time has gone on (and I'm sure more people are wheeling these) it seems like the general consensus is now around 45-50ml of 10-20K cst silicon in a blue hub with most people running 15k and saying that was the sweet spot. A few people running 15k said their fan was roaring at any takeoff after warmup and had some belt squeal as well on startup.
Hopefully someone knows something about the newer fan clutches and if anything can be done with them.
Understanding how viscous clutches work
Original 80 series thread on blue hub fan clutches (super long)
Link to a good summary of 100 fan clutch thread
Good thread on general procedures for fan clutch maintenance
100 series - clutch rebuild summary post
On to my point, has anyone ever rebuilt the Asin FCT-075GX470 fan clutch and replaced or added silicone oil to make it lockup better?
For some context many of the 80 and 100 series guys have done this but basically all of them use the "blue hub" version which are an Asin FCT-004 for the 80 and an Asin FCT-021 for the 100. On the 100 though the FCT-021 is only the factory fan clutch from 98-05. I've seen that either of these models can have their activation temperature adjusted and 95°F is what landtank sells theirs at for the 80 series. On the 100 I've read that people adjusted them between 95-110°F. Halfway through 2005, the 100 clutch goes to the Asin FCT-075 which is the same one thats used in the GX470 and there is no info about these but I'm pretty certain that they are non-adjustable. I did find that the FCT-021 is thinner than the FCT-075 so I'm not sure if this would work on a 470 anyway. It also seems like the fans were different in the 100s that used the newer model fan clutch so the stock fan might not bolt in correctly on the GX or be too far out of the fan shroud.
As far as fluid, the stock fluid in the blue hub clutches is 3-5k depending on the model number and more weight and/or more fluid means more drag and thus more lockup. In the earlier portions of the thread many people were saying they were running 7-9k fluid but as time has gone on (and I'm sure more people are wheeling these) it seems like the general consensus is now around 45-50ml of 10-20K cst silicon in a blue hub with most people running 15k and saying that was the sweet spot. A few people running 15k said their fan was roaring at any takeoff after warmup and had some belt squeal as well on startup.
Hopefully someone knows something about the newer fan clutches and if anything can be done with them.
Understanding how viscous clutches work
Original 80 series thread on blue hub fan clutches (super long)
Link to a good summary of 100 fan clutch thread
Good thread on general procedures for fan clutch maintenance
100 series - clutch rebuild summary post
