For sure will be posting more on it.
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Electric Fan clutch
- Thread starter ak diesel driver
- Start date
ak diesel driver
6.5 driver
So I found out today there's a pretty good chance the newer dmax fan clutch might fit. I measured the nut on it (not the threads) and it appears to be the same as the ones on the 6.5. Down side is the nut is quite a bit longer and the fan is 25". Measured the blades I'd be using and by the time I trimmed them down they'd be pretty similar. I'll have to hit a wrecking yard soon and get some better info. The Hayden number is 3202 but when I called them they didn't seem to have much info.
- Staff
- #163
Look for one from a van, not a truck. Theres 2 different electric fan clutches for the duramax, the 11+ truck, then the van and medium duty clutch. The 11+ truck uses the BIG fan as well as the medium duty trucks, but the van was a 21" fan. In 08 the duramax van could have came with the same fan blade and clutch as 01-05 trucks or the electric clutch with a 6 bolt fan. 99% certain the fan blades are the same size as they only list one shroud for 08 but 2 different fan/clutch arrangements. It also appears to be a shorter design. And all duramax's use the same 36mm thread size I believe.
ak diesel driver
6.5 driver
So according to RA the electric fan clutch started in 09 but they also list the thermal for 09. have to get into 10 before they list a Hayden unit and it's a 3222 instead of the truck ones which are 3202. Also on Ebay the fan clutch specs on the thread say 47mm or 1.86" which just so happens to be the size of the nut across the wrench flats.
Looking at fans the only dimension I can find is on amazon and they're showing 23", maybe shipping size? If it is 23" then obviously it would have to be trimmed too just not as much. fan numbers are 15228374, and 1580920
Looking at fans the only dimension I can find is on amazon and they're showing 23", maybe shipping size? If it is 23" then obviously it would have to be trimmed too just not as much. fan numbers are 15228374, and 1580920
ak diesel driver
6.5 driver
So a friend of mine ordered and received a fan clutch and fan for an 2010 Express van. Should find out today if the threads are right. The fan is 21" and he says it looks alot like the 9 blade metal fan that I gave him. I appears to operate differently than mine so we'll see how that works out. If nothing else I might have found a fan for my fan clutch.
ak diesel driver
6.5 driver
So here's pics. Differences I can see is mainly fan mounting. On my current set-up the fan is outboard an this is in board
ak diesel driver
6.5 driver
So here's the fan clutch installed. Seems to fit the shroud pretty good as far as fore/aft. He had a 9 blade steel fan on there before. He says standing in front of the grill running the throttle he could feel the air getting sucked thru his clothes where as before he couldn't. He's going to be doing some towing this weekend and will weigh 8-9 k. So I'll report back how it works out.
JayTheCPA
Well-Known Member
Looking forward to the update 
Will L.
Well-Known Member
Be cool to see the results! And yes, pun intended.
I gave serious thought to this when you brought up details. Instant control could have such an impact like you are coming up to the same hill you know always raises temps, so kicking it on early and dropping
Temps a bit before the load can make a nice difference.
I am just so focused on 100% lockup for my Hummer because of a couple friends in the USMC that experimented with hmmwvs and the difference of 85% lockup vs 100% cost them some engines. Hummer/ hmmwv cooling system design & aerodynamics is SO much worse than any GM pickup it is sad.
For pickups I know the 100% would help, but this should make a nice difference.
I imagine in the dash controls for temps setting so guys running long flatland runs and allowing their temp to dial in up to 205 to get the extra bump in mpg from the free heat, and then when the temps raise a hair too much being able to just turn it down.
And of coarse the all important towing heavy today so kick that fan in super early the whole time and pay a tad more in diesel to keep the engine way aways from any danger.
Then just keep it at the safe normal levels for day to day driving most of the year. I expect similar use from 100% lockup, but the electro-viscous should do better at the mpg side of things on this is my guess.
Has this rig been tracked mpg recently? If so, awesome. Please let us know any details on that along with cooling differences.
I gave serious thought to this when you brought up details. Instant control could have such an impact like you are coming up to the same hill you know always raises temps, so kicking it on early and dropping
Temps a bit before the load can make a nice difference.
I am just so focused on 100% lockup for my Hummer because of a couple friends in the USMC that experimented with hmmwvs and the difference of 85% lockup vs 100% cost them some engines. Hummer/ hmmwv cooling system design & aerodynamics is SO much worse than any GM pickup it is sad.
For pickups I know the 100% would help, but this should make a nice difference.
I imagine in the dash controls for temps setting so guys running long flatland runs and allowing their temp to dial in up to 205 to get the extra bump in mpg from the free heat, and then when the temps raise a hair too much being able to just turn it down.
And of coarse the all important towing heavy today so kick that fan in super early the whole time and pay a tad more in diesel to keep the engine way aways from any danger.
Then just keep it at the safe normal levels for day to day driving most of the year. I expect similar use from 100% lockup, but the electro-viscous should do better at the mpg side of things on this is my guess.
Has this rig been tracked mpg recently? If so, awesome. Please let us know any details on that along with cooling differences.
ak diesel driver
6.5 driver
Thing I'm the most curious about is how this fan compares to the 01 Duramax fan every one is using. IIRC WW said he thought the 9 blade steel was pretty comparable to that fan. My buddy seems to think this fan moves quite a bit more than the 9 blade he took off.
Will L.
Well-Known Member
John Kennedy did testing and showed the 9 blade steel #15992650 moved more air than the dmax fan.
That's before trimming a dmax fan which would reduce flow even more.
A few years back I did searching around for more info on the different fans, couldn't find a lot, but all the at home tests I read about seem to confirm John's info.
That magic meter of yours would be cool for testing airflow volume.
That's before trimming a dmax fan which would reduce flow even more.
A few years back I did searching around for more info on the different fans, couldn't find a lot, but all the at home tests I read about seem to confirm John's info.
That magic meter of yours would be cool for testing airflow volume.
Kennedy never published the results and desperately wants to stay out of this controversy. He's indicated they more or less equal out at higher (than idle) RPM. Plastic flexes so the blades can flatten out some under high RPM due to air resistance. (It could in theory flatten out too much giving a CFM win to the steel fan.) His clutch was calibrated for the steel fan with concern, published on his site, the Duramax fan took too much power overloading the torque rating of the clutch. They no longer make the steel fan so he has no choice anymore.
Towing hard I don't see a measurable difference between them as they kept ECT under control.
The Duramax fan does pull more air at idle and results in colder AC at extended idle for ole patch in our extreme weather. I have tested this due to engine mount failure requiring the steel fan for clearance till I fix it. The AC started to kick the high side safety switch out during the long idle times in a parking lot while using the steel fan. It's like 117 out when this happens.
The Project truck even on the krap R134a with the Dmax fan Kennedy Clutch combo will freeze you out of the cab.
The delay to get the clutch locked in from a cold start is my only bitch about obsolete Spring thermal clutches. The Electronic Dodge clutch can't come on fast enough and combined with a ECM bug blows the AC relief valve 2x a year at 450-500 PSI. Otherwise it's ability to lock up 10 min before the obsolete clutches is literally a decade ahead of the obsolete GM diesel designs providing cold air reliably before the engine warms up. Even when GM used the troublesome EV clutches on Trailblazers they let so much air recirculate over the top of the radiator from a piss poor design the AC never got that cold out here. Hidden under the plastic was how I fixed it both OEM and as shown with a Ron Davis radiator. GM was so close and screwed it up anyway. I could literally stick my hand through the hole!
Towing hard I don't see a measurable difference between them as they kept ECT under control.
The Duramax fan does pull more air at idle and results in colder AC at extended idle for ole patch in our extreme weather. I have tested this due to engine mount failure requiring the steel fan for clearance till I fix it. The AC started to kick the high side safety switch out during the long idle times in a parking lot while using the steel fan. It's like 117 out when this happens.
The Project truck even on the krap R134a with the Dmax fan Kennedy Clutch combo will freeze you out of the cab.
The delay to get the clutch locked in from a cold start is my only bitch about obsolete Spring thermal clutches. The Electronic Dodge clutch can't come on fast enough and combined with a ECM bug blows the AC relief valve 2x a year at 450-500 PSI. Otherwise it's ability to lock up 10 min before the obsolete clutches is literally a decade ahead of the obsolete GM diesel designs providing cold air reliably before the engine warms up. Even when GM used the troublesome EV clutches on Trailblazers they let so much air recirculate over the top of the radiator from a piss poor design the AC never got that cold out here. Hidden under the plastic was how I fixed it both OEM and as shown with a Ron Davis radiator. GM was so close and screwed it up anyway. I could literally stick my hand through the hole!
ak diesel driver
6.5 driver
my buddy says it takes 8 seconds to be fully on. Says your can hear it winding up.
Husker6.5
135' diagonal 16:9HD, 25KW sound!
Does it sound like one of those hand-cranked WWII air raid sirens when it does? That would definitely scare away the moose and elk, better than deer whistles on the bumper!
- Staff
- #175
It's the same fan blade, only difference is the 01-05 fan blade mounts with 4 bolts to the fan clutch, and the 09 evc van blade mounts with 6 bolts. In 08 you could get the duramax van with either fan arrangement even.
It can come on fast. Officially EV clutches are given 2 full min to respond to speed change requests before the computer trips a code. Further the Trailblazers refused to send commands to the EV fan for a full 2 min after startup no matter what the AC pressure, ECT, or ECM tables called for. I have logs showing ECT running away and AC kicking out during this time. NA to an independent control, but, shows you the design parameters of the fan where it can take time for cold silicone fluid to move and kick out the fan: and it's dependent on RPM where testing requires 2000 RPM and 2 min before it's considered failed. I will be monitoring the Dodge in the future to see how fast the fan comes on as I am tracking down where the AC blows out the relief and how to fix it for the '03 - 07 5.9's. Just to fix mine really. Either the fan can't respond fast enough at idle RPM or the ECM has a delay in it. Any delays like the Trailblazer had IMO, educated guess, the 2 min control delay to reduce the fan locked 100% during morning sickness. On the on ramp for a freeway a 100% locked fan could slip the belt let alone suck a lot of HP. The real reason is unknown to me. Overdriven fan, 6500 RPM redline of that LS2 Trailblazer SS and the fan belt was screaming during the tests I did at higher RPM to come up with the CFM of the fan being ~10,000.
Your adaption has potential. The best advice I offer is to try and keep the AC condenser below 160 degrees when controlling it for the AC. AC doesn't need 100% of the fan except possibly at idle. It just needs some fan when the condenser starts to warm up.
ak diesel driver
6.5 driver
So just got off the phone with my buddy and the fan clutch/fan setup worked flawlessly. His trailer weighed 9k. He took it up the hill out of Fairbanks which though not super steep is pretty long as in several miles. And no heat issues whatsoever. I have another friend with a 99ccdually towing a horse trailer and even with a fresh fan clutch had to really watch the temps on the same hill.
First guy with electric fan clutch has a 93 and also an ATT he turned up his pump before heading out, it only had a 1/4 turn left, said he spent most of his time watching the boost guage as he could super easily peg his 15 psi guage. Said based on how fast it climbed he could easily hit 20-25 psi. I'm thinking he needs to advance his timing a bit and it might drop his boost a bit. Any thoughts?
First guy with electric fan clutch has a 93 and also an ATT he turned up his pump before heading out, it only had a 1/4 turn left, said he spent most of his time watching the boost guage as he could super easily peg his 15 psi guage. Said based on how fast it climbed he could easily hit 20-25 psi. I'm thinking he needs to advance his timing a bit and it might drop his boost a bit. Any thoughts?
The ATT is known for 18 PSI on my 1993 and slightly more as spike during a shift. I really don't think they are getting much over 20 PSI unless he has a wild build. Suggest a digital boost gauge that can go to 30 PSI.
Advancing timing for the turbo I don't recommend if it's running good. You could lag it or melt down on low EGT's with too much advance. One of the better guides regarding this is here now on the Wayback machine: https://web.archive.org/web/20161102065106/http://www.oliverdiesel.com/tech/timing.htm
Advancing timing for the turbo I don't recommend if it's running good. You could lag it or melt down on low EGT's with too much advance. One of the better guides regarding this is here now on the Wayback machine: https://web.archive.org/web/20161102065106/http://www.oliverdiesel.com/tech/timing.htm
ak diesel driver
6.5 driver
Completely stock other than 4" exhaust ATT and turned up pump
ak diesel driver
6.5 driver
So I ordered the clutch, fan,and controller from RockAuto. IIRC the before shipping price for everything was $178. The price including shipping was right at $240. I think this is a pretty good price for a bolt on upgrade.