Viscous Fan Clutch Replacment
- Thread starter cahaak
- Start date
Midwestdrifter
Engineer In Residence
There in undoubtedly a speed where the fan blades start to resonate due to shed vortices. Given the large rpm range the fan operates over, its impossible to tune the blade length and chord width to eliminate all the possible vibration modes. To avoid fatigue failure the resonant frequencies need to be canceled at least to the 1st order. This also makes the fan quieter. One method to accomplish this is by have a decreasing blade spacing in several successive blades (2-3 groups usually). As it is still symmetric, the balance is not affected. The different spacing means the shed vortices impact the trailing blades at slightly different rates preventing them from stacking from one blade to the next.
For fixed speed or narrow speed fans this is less of an issue. blowers or fans where both ends of the blade are supported have less of an issue with this.
For fixed speed or narrow speed fans this is less of an issue. blowers or fans where both ends of the blade are supported have less of an issue with this.
marklg
Well-known member
That can clearly be seen on both fans. The older blade has 7 blades, spaced differently. The new fan has 9, also spaced differently. I don't see a clear line of symmetry, but I would guess they are arranged such that the balance is not affected. The new fan is less noisy than the old, but it also may be that the clutch is not fully engaging. Coolant temps with the old hovered around 180-190. With the new, they are in the 190-200 range.
Regards,
Mark
I was surprised when the operating temperatures on the 2004 actually increased a bit with the new clutch. The new clutch roars more upon a morning cold start than did the replaced clutch. (Viscous fluid pools overnight.)
My typical low temperature rose, the high peaks came down after the new clutch. My theory for the unexpected slight rise in lower operating temperature is that my 2004 clutch was stuck in some mid range operating condition. It never locked up completely or disengaged, but did kinda work in a limited range. When the engine is hot the thermostat opens completely. It takes a bit of a temperature drop for it to cycle back. At that time it is the fan speed which becomes an important factor for trimming the temperatures to design, not the thermostat. With the 2004 fan never properly disengaging the engine was being supercooled at times.
vic
marklg
Well-known member
The knockoff clutch failed in the middle of nowhere, in the desert, driving along when suddenly the engine noise increased to a roar. I guess it was a good thing it failed completely on. The rise in temperature after replacement was as expected. We will have to see what the temp gets to climbing hills at high ambient temperature.I was surprised when the operating temperatures on the 2004 actually increased a bit with the new clutch. The new clutch roars more upon a morning cold start than did the replaced clutch. (Viscous fluid pools overnight.)
My typical low temperature rose, the high peaks came down after the new clutch. My theory for the unexpected slight rise in lower operating temperature is that my 2004 clutch was stuck in some mid range operating condition. It never locked up completely or disengaged, but did kinda work in a limited range. When the engine is hot the thermostat opens completely. It takes a bit of a temperature drop for it to cycle back. At that time it is the fan speed which becomes an important factor for trimming the temperatures to design, not the thermostat. With the 2004 fan never properly disengaging the engine was being supercooled at times.
The first clutch, before the knockoff, had failed off, so the electric fan was running all the time, and the temp rose drastically on hills. So, at least I have data points for fully off, fully on, and normal operation.
Regards,
Mark
Nautamaran
2004 140” HRC 2500 (Crewed)
This is about what I saw too, driving Calgary to Vancouver in late May.
Peak temp reached 225F on the long climbs, with atf sump at 240F and oil temperature reaching around 280F. Coolant recovered first, the atf, then engine oil. Ambient temp was mid-70’s.
I’ve read that some have instrumented the exhaust manifold to measure Exhaust Gas Temp, and after watching my oil temp spike up I can understand why, but that’s for another thread.
-dave
I just sent the following message to Europarts-SD. I think it captures what's been going on. I've still never heard any roaring of the fan when engine is hot. And on more demanding drives, the van has overheated. Most cooling components had already been replaced recently, except the viscous fan clutch. Whether related to previous overheating or not, the reservoir on my radiator had split, the water pump had begun leaking, and even the aux pump started leaking at the seam. Normal operating temp is about 190F, climbing up to 220F or even nearer 250F on hotter days. My desire would be to go out on the road without worry of overheating on longer climbs. Van has 190k on it currently.
Also, to be appropriate for this thread, I will add that I was able to change the fan clutch by only removing the heat shield. I was able to feel around for the 8mm allen bolt and eventually got the allen wrench into it. The handle of my allen wrench is pretty long (8" ?) and provided enough torque. I used a screwdriver to hold the fan from turning. Once the bolt was loose, I switched to a shorter allen wrench. My hands are medium size and that probably helps. Also, I wore latex gloves which I think saved my knuckles from scraping on the fins of the radiator. Older fan clutch was Mercedes, new one is Cool Xpert (?) from Europarts.
----
First of all, thank you for your great selection, helpful product descriptions and quick shipping! I’m a happy repeat customer.
I received the viscous fan clutch I ordered recently and installed it. But I seem to still have some issue.
My hope was that the new clutch would improve the cooling on my 2005 Sprinter 2500. On a local hill, the van regularly borders on overheating, especially on a hot day with a/c running. Its a relatively short drive - 20 minutes uphill, and then 20 down the other side. I’m not towing anything but I do have some amount of load in the van. Recently with the old fan clutch, I pulled over while van was quite hot (~220F according to the dash meter) and while it was still running, I verified that the fan could be easily stopped with a piece of soft foam. This, I believe, indicated that a new clutch was needed.
With the new fan clutch installed, I made the same drive, Again the van came close to overheating, and I pulled over to test the fan clutch. Even with the new clutch, I was able to easily stop the fan from turning while the engine was hot (again ~220F) and engine running.
Perhaps I received a bad unit ? Should I send this back for a different fan clutch ? What do you recommend at this point ?
----
So that was my message to Europarts. But I'd like to pose these questions here as well. From all I've read on this forum, even a new viscous fan clutch part might not behave as desired.
Also, to be appropriate for this thread, I will add that I was able to change the fan clutch by only removing the heat shield. I was able to feel around for the 8mm allen bolt and eventually got the allen wrench into it. The handle of my allen wrench is pretty long (8" ?) and provided enough torque. I used a screwdriver to hold the fan from turning. Once the bolt was loose, I switched to a shorter allen wrench. My hands are medium size and that probably helps. Also, I wore latex gloves which I think saved my knuckles from scraping on the fins of the radiator. Older fan clutch was Mercedes, new one is Cool Xpert (?) from Europarts.
----
First of all, thank you for your great selection, helpful product descriptions and quick shipping! I’m a happy repeat customer.
I received the viscous fan clutch I ordered recently and installed it. But I seem to still have some issue.
My hope was that the new clutch would improve the cooling on my 2005 Sprinter 2500. On a local hill, the van regularly borders on overheating, especially on a hot day with a/c running. Its a relatively short drive - 20 minutes uphill, and then 20 down the other side. I’m not towing anything but I do have some amount of load in the van. Recently with the old fan clutch, I pulled over while van was quite hot (~220F according to the dash meter) and while it was still running, I verified that the fan could be easily stopped with a piece of soft foam. This, I believe, indicated that a new clutch was needed.
With the new fan clutch installed, I made the same drive, Again the van came close to overheating, and I pulled over to test the fan clutch. Even with the new clutch, I was able to easily stop the fan from turning while the engine was hot (again ~220F) and engine running.
Perhaps I received a bad unit ? Should I send this back for a different fan clutch ? What do you recommend at this point ?
----
So that was my message to Europarts. But I'd like to pose these questions here as well. From all I've read on this forum, even a new viscous fan clutch part might not behave as desired.
lindenengineering
Well-known member
For info on the 2002 to 2003 fans the blades are NOT asymmetrical.
With the right tools its a 20 minutes TOPs wrenching exercise to change that fan.
Dennis
With the right tools its a 20 minutes TOPs wrenching exercise to change that fan.
Dennis
@altide8
My water pump went out right after I paid a shop a lot of money to do the serpentine belt and pulleys, plus a bunch of other work. I asked at that time about replacing the pump and the service advisor told me it was not necessary, I should have known better but I was strapped for time. No need to go back there, time for me to learn how to fix this thing properly. Thank you Sprinter Source!
Its been a while since I did this so from my hazy memory . . .
There was another member here who made these tools and used to sell them but no longer so I made my own. Its pretty simple, the 'Hook' tool will grab one of the fan blade bolts and the spine of the tool will then interfere with the viscous unit body/shaft (eg like I show with the hood latch pictures). This will allow you to use the other 'Allen' tool and loosen the bolt.
You 'Hook' on one side to loosen and then the other to tighten.
My water pump went out right after I paid a shop a lot of money to do the serpentine belt and pulleys, plus a bunch of other work. I asked at that time about replacing the pump and the service advisor told me it was not necessary, I should have known better but I was strapped for time. No need to go back there, time for me to learn how to fix this thing properly. Thank you Sprinter Source!
Its been a while since I did this so from my hazy memory . . .
There was another member here who made these tools and used to sell them but no longer so I made my own. Its pretty simple, the 'Hook' tool will grab one of the fan blade bolts and the spine of the tool will then interfere with the viscous unit body/shaft (eg like I show with the hood latch pictures). This will allow you to use the other 'Allen' tool and loosen the bolt.
You 'Hook' on one side to loosen and then the other to tighten.
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My strong suggestion to anyone getting into this area to do water pump, serpentine belt, idlers, dampner, is to CUT the plastic radiator shroud on the right side at the intersection of the round portion and flat transition. Just to the right of the tools in the first picture, detail in the second photo. You can then lift it up and place it on top of the engine cover/intake manifold.
Drill 3 holes on each side of the cut so you can thread zip ties through the cut and 'stitch' it back together when you are done. The OEM metal clips and zip tie stitch keep everything in place very solid.
When I did my water pump I removed the top crossmember, cut the shroud and was able to lean the whole radiator assembly forward enought that I could get a standard allen head socket onto the Viscous bolt and had no need for the special 'Allen' tool I had made
Yes it was a chunk of stuff to remove but it really afforded a lot of access space for my gorilla hands.
Cheers, Chris
Drill 3 holes on each side of the cut so you can thread zip ties through the cut and 'stitch' it back together when you are done. The OEM metal clips and zip tie stitch keep everything in place very solid.
When I did my water pump I removed the top crossmember, cut the shroud and was able to lean the whole radiator assembly forward enought that I could get a standard allen head socket onto the Viscous bolt and had no need for the special 'Allen' tool I had made
Yes it was a chunk of stuff to remove but it really afforded a lot of access space for my gorilla hands.
Cheers, Chris
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lindenengineering
Well-known member
To remove the fan you use something like this with a 1/4 drive allen bit. We buy them from Matco--not "Harbor fright"
www.harborfreight.com
.
Slip out the two U clips securing the fan cowl on the left side as you work on the rig.
Gently lift up and push the LEFT SIDE cowl back to expose the fan access. There is enough flex to allow this without busting it .
Insert the tool from the left side and release the allen bolt.
Pull out the fan from the left side opening.
Remove the other side U clips and pull out the cowl.
I refuse to remove appendages I don't need to!
Dennis
1/4 in, 3/8 in. Drive Long Reach Dual Flex Head Ratchet
1/4" and 3/8" Drive x 14-3/8" Double Flex Head Ratchet Wrench
www.harborfreight.com
Slip out the two U clips securing the fan cowl on the left side as you work on the rig.
Gently lift up and push the LEFT SIDE cowl back to expose the fan access. There is enough flex to allow this without busting it .
Insert the tool from the left side and release the allen bolt.
Pull out the fan from the left side opening.
Remove the other side U clips and pull out the cowl.
I refuse to remove appendages I don't need to!
Dennis
I agree on cutting the fan shroud. Here is a link that shows my solution that speeds up the reassembly: https://sprinter-source.com/forums/index.php?threads/28453/
I see how it would be easy enough to cut the shroud and zip tie it back together. Dennis's solution seems more professional. Its good to know its possible to get the shroud out of the way without the full disassembly.
Although awkward, I was able to remove fan and clutch together without doing any of that. I did remove the heat shield to give a little more access and then I could even get both hands in there.
All that said, my new viscous fan clutch doesn't seem to engage. The dash showed temperature getting up to about 235F or 240F. I pulled over and was still able to easily stop the fan. Am I correct to assume I don't have a functional part ?
Although awkward, I was able to remove fan and clutch together without doing any of that. I did remove the heat shield to give a little more access and then I could even get both hands in there.
All that said, my new viscous fan clutch doesn't seem to engage. The dash showed temperature getting up to about 235F or 240F. I pulled over and was still able to easily stop the fan. Am I correct to assume I don't have a functional part ?
ORsprinter
New member
I should have went the cut the shroud route. It took me 30 min to change the fan but 60 minutes to try to put that one clip on the right side back. It requires angles my human hands couldn't pull off.
I didn't have a low enough profile socket to unbolt the fan and didn't have enough room/dexterity to turn the allen wrench to be honest. Once loosened (narrow pipe to extend the allen wrench), I found that tying a fishing line to the long end of the allen wrench and using it like a puppet string to turn the wrench did the trick (and tied off the top end so I didn't curse each time it dropped into the bottom recesses of the stack).
I love that DIY types worry about "professional". Git er' done works for me.
This is the T1N section. The newest T1N is now 14 years old.
Next time I need to change a coolant pump or viscous clutch I'm carving the fan shroud like it is a Sunday roast. Need to replace my heater core aka matrix??? The heater case will get carved up the same way if it helps. We cut up a similar age to T1N's Dodge B series van plastic heater case to replace the heater core. It worked fine. Aluminum tape and a couple pop riveted strap jumpers held it together after the surgery. Was it "professional"... no way. Did it save problems and work?? You bet.
Carry on.
vic
This is the T1N section. The newest T1N is now 14 years old.
Next time I need to change a coolant pump or viscous clutch I'm carving the fan shroud like it is a Sunday roast. Need to replace my heater core aka matrix??? The heater case will get carved up the same way if it helps. We cut up a similar age to T1N's Dodge B series van plastic heater case to replace the heater core. It worked fine. Aluminum tape and a couple pop riveted strap jumpers held it together after the surgery. Was it "professional"... no way. Did it save problems and work?? You bet.
Carry on.
vic
1Latahrog
New member
I apologize as a rookie on this forum. I posted re:clutch engage disengage specs on one of the other threads re:viscous fan clutch. I find it interesting that it is said here the 9 fin fan is quieter. My original 9 fin fan, maybe replaced by previous owner 9years ago, was noticeably louder than the recently installed by Mc Coy Freightliner, Portland OR 7 fin fan. They told me when I was concerned about running hotter that the New 7 fin fan runs quieter and I just wasn't hearing it.??? Regardless, thank ya'll for the replacement instructions/tips! Thanks Roger