Opinion on Fan Clutch diagnosis?
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Rock Crawling
Joined: Dec 2012
Posts: 436
Likes: 141
From: Birmingham, AL
Opinion on Fan Clutch diagnosis?
Hey guys,
I've been reading up on Fan Clutches because I have suspicions that mine is on it's way out. I have an 04' Disco with a 98' P38 motor. Most of the cooling system has been refreshed in the last two years. Other than the radiator, water pump, and fan clutch.
I just finished replacing the AC condenser fan. Simple project, and thanks to the forum I spent $50 on a fan motor instead of $250+ on the fan motor + fan/shroud assembly.
180 degree OE thermostat, no inline mod. No overheating issues, coolant temps runs between 190-199 in slow speed stop and go conditions. 180-194 on the interstate. Idling is usually sub 200, but if left sitting temp will rise to 205+. Highest I've seen is 215 after idling for 25 minutes with ac full blast - that is how I learned the AC condenser fan was not working. The auxillary fan would not come on at 212 to cool the motor back down to 202. Pulled the grill off and found that it was seized.
Fan Clutch: I get no audible fan roar/ woosh noise on startup. I also get no fan roar/woosh when the truck gets hot and you would expect the fan clutch to engage. Like I mentioned above, no overheating, temps are always sub 200.
Cold Motor: When I turn the fan it only turns a fraction of a revolution, and has good resistance. But, if I push it a couple of times, on the the third push it will spin about a full revolution before stopping. It does not feel like there is "Peanut butter" in the fan clutch per the sticky post. I have not spun it with the motor warm recently. But I can and report back.
My questions: I've diagnosed fan clutches before, and this one seems to be failing.
1) Those of you who have replaced yours, how long did it take before it failed and provided no cooling benefit?
2) Since it will not turn much when I first try to push it, am I overanalyzing this? Is it actually fine and I am just trying to find an excuse to replace it since temps are good?
3) I will likely have my mechanic tackle the clutch, but he trusts me to provide parts. I've read many posts about fan clutches, but share your favorite replacement fan clutch please!
4) Is it worth inspecting and possibly replacing the water pump while doing the fan clutch since they are on the same shaft?
Thank you for reading my long winded post. Huge thanks to the regular contributors here. I have learned a ton, and I've already tackled a bunch of projects made much easier by the forum!
- Andrew
2004 Discovery
Epsom green
153k on chassis
~80k on P38 4.6
Purchased from forum member
totally stock other than terra firma shocks and pirelli scorpion a/t tires
I've been reading up on Fan Clutches because I have suspicions that mine is on it's way out. I have an 04' Disco with a 98' P38 motor. Most of the cooling system has been refreshed in the last two years. Other than the radiator, water pump, and fan clutch.
I just finished replacing the AC condenser fan. Simple project, and thanks to the forum I spent $50 on a fan motor instead of $250+ on the fan motor + fan/shroud assembly.
180 degree OE thermostat, no inline mod. No overheating issues, coolant temps runs between 190-199 in slow speed stop and go conditions. 180-194 on the interstate. Idling is usually sub 200, but if left sitting temp will rise to 205+. Highest I've seen is 215 after idling for 25 minutes with ac full blast - that is how I learned the AC condenser fan was not working. The auxillary fan would not come on at 212 to cool the motor back down to 202. Pulled the grill off and found that it was seized.
Fan Clutch: I get no audible fan roar/ woosh noise on startup. I also get no fan roar/woosh when the truck gets hot and you would expect the fan clutch to engage. Like I mentioned above, no overheating, temps are always sub 200.
Cold Motor: When I turn the fan it only turns a fraction of a revolution, and has good resistance. But, if I push it a couple of times, on the the third push it will spin about a full revolution before stopping. It does not feel like there is "Peanut butter" in the fan clutch per the sticky post. I have not spun it with the motor warm recently. But I can and report back.
My questions: I've diagnosed fan clutches before, and this one seems to be failing.
1) Those of you who have replaced yours, how long did it take before it failed and provided no cooling benefit?
2) Since it will not turn much when I first try to push it, am I overanalyzing this? Is it actually fine and I am just trying to find an excuse to replace it since temps are good?
3) I will likely have my mechanic tackle the clutch, but he trusts me to provide parts. I've read many posts about fan clutches, but share your favorite replacement fan clutch please!
4) Is it worth inspecting and possibly replacing the water pump while doing the fan clutch since they are on the same shaft?
Thank you for reading my long winded post. Huge thanks to the regular contributors here. I have learned a ton, and I've already tackled a bunch of projects made much easier by the forum!
- Andrew
2004 Discovery
Epsom green
153k on chassis
~80k on P38 4.6
Purchased from forum member
totally stock other than terra firma shocks and pirelli scorpion a/t tires
Rock Crawling
Joined: Aug 2019
Posts: 427
Likes: 138
From: Boston, MA
I'd agree that it sounds like your clutch is worse for wear. I'm not sure of the service history of mine, but I can tell a difference on startup and when idling for a while - you can really hear the fan once it's replaced with a new part. You should definitely inspect, and strongly consider replacing the water pump while you're in there.
The fan and fan clutch (and the water pump too) is a pretty easy replacement if you have the right tools. Your temps are good but I find that the fan is really effective at keeping temps down in hot weather with the AC on, even if your AC condenser fan is seized (mine is, as is the hardware holding it in place).
You'll need these tools: water pump pulley holder and a 36mm fan clutch wrench. I tried using different tools to remove it, including a big hammer in lieu of the water pump pulley holder, and just take my word for it and get the tools. The fan will come off in 5 minutes.
Take off the fan with those tools, remove it, then pull off the serpentine belt - good time to inspect/replace it. Once the serp belt is off, grab the water pump pulley and yank up and down and left/right to check for play in the shaft. If there is any movement, then you need a water pump. $40 for a new one from Lucky8 and it's an easy swap. Check all of your other accessory belt pulleys for play, too - I found an idler pulley with shot bearings. You just need to make sure that each spins freely and doesn't have any play when wiggling it around. The belt has to be off in order to check.
Conventional wisdom says to replace the water pump and fan/fan clutch at the same time, since they turn on the same shaft. Adding a new more robust clutch/fan will put extra stress on the water pump pulley shaft and if yours is already getting worn, this could cause it to fail. Failing water pump shaft can be catastrophic (e.g. the fan going through the radiator/hood). Not everyone does this but it's cheap insurance. The water pump replacement will take 1-2 hours - the bulk of this time will be spent chipping off the old gasket from the front cover with a razor blade. You need to do a good job or you won't get a good seal, and if you gouge up the front cover with like a metal scraper, then your new pump won't seal. Just an exercise in patience. Other than that, it's an easy replacement - there are like 8 or 9 bolts that hold on the water pump and there are some great videos on YouTube showing the process.
After reassembling, you just need to do a good job topping up the coolant and bleeding correctly. I found that the best way to do this is to remove the bleeder screw and pour coolant into the reservoir until it won't take any more. At this point, the hose where the bleed screw is will still have a large air bubble. Grab the coolant hose next to the bleeder screw and squeeze it to push air out of the screw hole. Then, use your finger to cover the screw hole and release the hose - this will pull coolant out of the reservoir tank into this hose. Repeat until you get coolant coming out of the bleeder screw - this is way easier than using a tiny funnel to pour coolant directly into the bleeder screw hole. Then, after your next few drives, check the coolant level and top up as necessary.
Here are the parts I'd recommend:
- Hayden 2991 Severe Duty Fan Clutch ($40 on RockAuto)
- Dorman 620-112 Radiator Fan ($20 on RockAuto)
- Lucky8 water pump ($40)
All said and done, for around $100 and an afternoon in your driveway/garage you can have the job done. Personally I think it'd be a waste of money to send it to the shop for this one. If you can do an oil change, then you can do the water pump and fan/fan clutch.
Edit: Noticed that you have an 04. The 03-04 models have a single unit fan clutch/fan setup, which is $250+ to replace. 99-02 models use a fan clutch that bolts to the fan. You don't need to get a $250 single unit, you can just replicate the setup in the 99-02 models where the fan clutch bolts to the fan, which threads onto the water pump. You'll need to buy four bolts and possibly some washers (M8? Sorry I don't remember offhand) to attach the fan to the fan clutch. Just bring the new fan clutch to the hardware store and get bolts that fit the threads and are the right length to secure the fan. Should only cost a few bucks.
The fan and fan clutch (and the water pump too) is a pretty easy replacement if you have the right tools. Your temps are good but I find that the fan is really effective at keeping temps down in hot weather with the AC on, even if your AC condenser fan is seized (mine is, as is the hardware holding it in place).
You'll need these tools: water pump pulley holder and a 36mm fan clutch wrench. I tried using different tools to remove it, including a big hammer in lieu of the water pump pulley holder, and just take my word for it and get the tools. The fan will come off in 5 minutes.
Take off the fan with those tools, remove it, then pull off the serpentine belt - good time to inspect/replace it. Once the serp belt is off, grab the water pump pulley and yank up and down and left/right to check for play in the shaft. If there is any movement, then you need a water pump. $40 for a new one from Lucky8 and it's an easy swap. Check all of your other accessory belt pulleys for play, too - I found an idler pulley with shot bearings. You just need to make sure that each spins freely and doesn't have any play when wiggling it around. The belt has to be off in order to check.
Conventional wisdom says to replace the water pump and fan/fan clutch at the same time, since they turn on the same shaft. Adding a new more robust clutch/fan will put extra stress on the water pump pulley shaft and if yours is already getting worn, this could cause it to fail. Failing water pump shaft can be catastrophic (e.g. the fan going through the radiator/hood). Not everyone does this but it's cheap insurance. The water pump replacement will take 1-2 hours - the bulk of this time will be spent chipping off the old gasket from the front cover with a razor blade. You need to do a good job or you won't get a good seal, and if you gouge up the front cover with like a metal scraper, then your new pump won't seal. Just an exercise in patience. Other than that, it's an easy replacement - there are like 8 or 9 bolts that hold on the water pump and there are some great videos on YouTube showing the process.
After reassembling, you just need to do a good job topping up the coolant and bleeding correctly. I found that the best way to do this is to remove the bleeder screw and pour coolant into the reservoir until it won't take any more. At this point, the hose where the bleed screw is will still have a large air bubble. Grab the coolant hose next to the bleeder screw and squeeze it to push air out of the screw hole. Then, use your finger to cover the screw hole and release the hose - this will pull coolant out of the reservoir tank into this hose. Repeat until you get coolant coming out of the bleeder screw - this is way easier than using a tiny funnel to pour coolant directly into the bleeder screw hole. Then, after your next few drives, check the coolant level and top up as necessary.
Here are the parts I'd recommend:
- Hayden 2991 Severe Duty Fan Clutch ($40 on RockAuto)
- Dorman 620-112 Radiator Fan ($20 on RockAuto)
- Lucky8 water pump ($40)
All said and done, for around $100 and an afternoon in your driveway/garage you can have the job done. Personally I think it'd be a waste of money to send it to the shop for this one. If you can do an oil change, then you can do the water pump and fan/fan clutch.
Edit: Noticed that you have an 04. The 03-04 models have a single unit fan clutch/fan setup, which is $250+ to replace. 99-02 models use a fan clutch that bolts to the fan. You don't need to get a $250 single unit, you can just replicate the setup in the 99-02 models where the fan clutch bolts to the fan, which threads onto the water pump. You'll need to buy four bolts and possibly some washers (M8? Sorry I don't remember offhand) to attach the fan to the fan clutch. Just bring the new fan clutch to the hardware store and get bolts that fit the threads and are the right length to secure the fan. Should only cost a few bucks.
Last edited by boston4; Jun 12, 2020 at 09:23 AM.
Thread Starter
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Rock Crawling
Joined: Dec 2012
Posts: 436
Likes: 141
From: Birmingham, AL
@boston4 Great info. Thank you for the detail. It certainly sounds in my ballpark to knock out the fan/water pump. I don't have a garage and have a busy schedule for the next couple of weeks, which is another big reason for considering the shop. That, and I am still getting P1174 and P1171 codes.
The most frustrating thing is that I just replaced both idler pulleys and the serp belt... Man, should have done the fan and water pump then!
Is there a benefit to swapping to the early DII style fan clutch? Other than cost savings that is. In your description it sounds like the early style DII fan clutch will bolt to my existing fan? Or would I need an early style fan as well?
Water pump sounds like a no brainer. Worth placing the $40 part for peace of mind.
The most frustrating thing is that I just replaced both idler pulleys and the serp belt... Man, should have done the fan and water pump then!
Is there a benefit to swapping to the early DII style fan clutch? Other than cost savings that is. In your description it sounds like the early style DII fan clutch will bolt to my existing fan? Or would I need an early style fan as well?
Water pump sounds like a no brainer. Worth placing the $40 part for peace of mind.
Rock Crawling
Joined: Aug 2019
Posts: 427
Likes: 138
From: Boston, MA
Agreed that the water pump is a no brainer - you'll spend a while with the old gasket but it's not a difficult job by any means.
It's not just a cost savings to swap to the early D2 style fan/fan clutch. The 03-04 replacement is $220 and it's one piece for the fan clutch and fan itself - I listed off a replacement fan and a replacement fan clutch that you can just bolt together - it'll save $160. You'll get better cooling as well, from a fan that moves more air and a fan clutch that engages more (severe duty instead of heavy duty). The Dorman fan that I listed has a more aggressive pitch to move more air, and it's white, which means it's super easy to check for cracks using a flashlight.
Codes sound like vacuum leaks.
It's not just a cost savings to swap to the early D2 style fan/fan clutch. The 03-04 replacement is $220 and it's one piece for the fan clutch and fan itself - I listed off a replacement fan and a replacement fan clutch that you can just bolt together - it'll save $160. You'll get better cooling as well, from a fan that moves more air and a fan clutch that engages more (severe duty instead of heavy duty). The Dorman fan that I listed has a more aggressive pitch to move more air, and it's white, which means it's super easy to check for cracks using a flashlight.
Codes sound like vacuum leaks.
Last edited by boston4; Jun 12, 2020 at 11:03 AM.
Camel Trophy
Joined: Sep 2017
Posts: 3,813
Likes: 1,331
From: Mission BC Canada
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Rock Crawling
Joined: Dec 2012
Posts: 436
Likes: 141
From: Birmingham, AL
I went ahead and scheduled some time with my mechanic. Appointment is not until July 6th. Figured I would go ahead and order the parts to do it myself, and if I end up not having the time then I have an appointment set where he can knock it out for me. Fortunately they are super cool about me ordering my own parts. I need to get him to him to look at my codes anyway. O2's report good readings and those codes are usually O2 related codes...
Not sure what his recommendation is, but I am willing to bet he wants to stay with the 03-04 style fan. $148 from Lucky 8 seems like a decent price. I spent half of my budget buying the car, the other half is for maintenance and mods, and oh s$*t circumstances. I think I'd rather make my life easier by spending an extra $90 or so in this case. I might not have access to another car to run around finding hardware while the disco is apart, it's my primary car at the moment. I also try and stick to the Keep It Simple Stupid mentality.
I have read a lot of posts about the severe duty fan clutch. It seems like the right play on the surface, but it also seems like it would take a lot more effort from the motor the power it? I know the cooling systems aren't exactly perfect on Discos to say the least, but I feel like a good OE replacement unit is more than enough to provide sufficient power. Does that seem to be the case, or is worth having the severe duty fan clutch? Just asking for opinions, from what I have read people seem to sit in both camps. It seems to me like with mine running as cool as it does with no fan clutch engagement, do I really need to upgrade the fan clutch?
I ordered the tools for the water pump job as you suggested from eBay. Sounds simple enough!
Not sure what his recommendation is, but I am willing to bet he wants to stay with the 03-04 style fan. $148 from Lucky 8 seems like a decent price. I spent half of my budget buying the car, the other half is for maintenance and mods, and oh s$*t circumstances. I think I'd rather make my life easier by spending an extra $90 or so in this case. I might not have access to another car to run around finding hardware while the disco is apart, it's my primary car at the moment. I also try and stick to the Keep It Simple Stupid mentality.
I have read a lot of posts about the severe duty fan clutch. It seems like the right play on the surface, but it also seems like it would take a lot more effort from the motor the power it? I know the cooling systems aren't exactly perfect on Discos to say the least, but I feel like a good OE replacement unit is more than enough to provide sufficient power. Does that seem to be the case, or is worth having the severe duty fan clutch? Just asking for opinions, from what I have read people seem to sit in both camps. It seems to me like with mine running as cool as it does with no fan clutch engagement, do I really need to upgrade the fan clutch?
I ordered the tools for the water pump job as you suggested from eBay. Sounds simple enough!
Thread Starter
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Rock Crawling
Joined: Dec 2012
Posts: 436
Likes: 141
From: Birmingham, AL
@Richard Gallant copy that. So the assembly just needs to be bolted together before installation right?
If that is the case, then that will work for me. Maybe I did not read @boston4 's post carefully enough.
If that is the case, then that will work for me. Maybe I did not read @boston4 's post carefully enough.
Camel Trophy
Joined: Sep 2017
Posts: 3,813
Likes: 1,331
From: Mission BC Canada
@arains44 What you are trying to avoid is any overheat of any kind. You have aluminum engine any overheat can warp the heads, can cause a slipped liner (very high temps generally) cause micro fracturing of the block. It does not matter who makes them they all suffer from these issues to some degree.
The stock fan in fine, it the stupid cost that has people using alternatives, fan clutches are literally ancient tech there is no reason for a fan and clutch to cost 200-400 dollars. The severe duty just locks up sooner and more, and the small amount of power loss is irrelevant literally.
This explains it https://www.haydenauto.com/en/techni...q-fan-clutches
The stock fan in fine, it the stupid cost that has people using alternatives, fan clutches are literally ancient tech there is no reason for a fan and clutch to cost 200-400 dollars. The severe duty just locks up sooner and more, and the small amount of power loss is irrelevant literally.
This explains it https://www.haydenauto.com/en/techni...q-fan-clutches
Rock Crawling
Joined: Aug 2019
Posts: 427
Likes: 138
From: Boston, MA
Yeah - it's an upgrade and it's cheaper to go for the 99-02 setup. The 03-04 setup isn't superior, it's just more expensive - you don't see anyone with 2001 trucks "upgrading" to the pressed clutch/fan unit that the 03-04s used.
The factory cooling system was, without question, barely adequate when it rolled off the production line. An upgrade that works better and costs less seems like a no brainer, especially since it's name brand parts. There will be some HP loss for the severe duty clutch, but not dramatically so. Most of the time it'll be at 25-40% engagement regardless of which one you pick - when the motor gets hot if you're stuck in traffic or sitting on a trail, then I'd rather have it pull more air and lose some mpg.
The factory cooling system was, without question, barely adequate when it rolled off the production line. An upgrade that works better and costs less seems like a no brainer, especially since it's name brand parts. There will be some HP loss for the severe duty clutch, but not dramatically so. Most of the time it'll be at 25-40% engagement regardless of which one you pick - when the motor gets hot if you're stuck in traffic or sitting on a trail, then I'd rather have it pull more air and lose some mpg.
