mechanical fan clutch

[ranger 393]

I don't know if anyone else has tried this, but I just replaced my mine this set up,and noticed a big difference in my engine temps..
The fan comes on a little sooner keeping your engine temps down. Drove it last week and the temps stay between 185-195.Before they were running about 205. So far I'm impressed with how it works, and hope its going top make a big difference with my 15k# toy hauler..

 

[CVR222NV]

Since the stock fan clutch is electric is there any issue with the ECM not seeing it when you eliminate it?

 

[Mikey-KE7LBB]

ECM will show a code, but not turn on the CEL. I have the same mod on my '09 2500 QC 4x4, and love it!!

 

[Mikey-KE7LBB]

One thing to warn you about is AC performance with short trips...

First start up with fan partially locked gives cold air, but will get warm if you stop for a few minutes to grab a soda... As long as your moving, short trips will be blowing cold! Once the thermostat opens and heats the radiator, AC will blow cold at idle for longer periods.

If you tow, no problems there at all!!

 

[AH64ID]

As @Mikey-KE7LBB mentioned you will lose AC performance. You’d be better off to get a custom tune that will change the ECM fan parameters if you want it to come on sooner, but even then the stock temps aren’t an issue for most.

If you’re hitting 205° empty then the thermostat is likely the issue, or possibly a plugged/bad radiator. The last thing I’d consider an issue is the fan clutch. The fan isn’t programmed to come on until higher, ~215°, so it’s not a fan issue. While towing 205° is nothing. The thermostat isn’t even fully open until 207°, but an empty 5.9 shouldn’t be running anywhere near that.

 

[Mikey-KE7LBB]

5.9's are known to chop the wires off with the fan, so results will be noticed right away with a swap... OE is probably best, but I've been pretty happy with my swap so far.

A cheap pusher fan would probably resolve any AC issues for short stop events, but 30 MPH is plenty to cool things down in 100°+ heat... Also, I've noticed that a 180° thermostat will get the radiator to temp much faster than stock, and improve AC performance.

 

[AH64ID]

While 5.9’a can cut the wires it’s not anywhere close to a common problem.

180° thermostat will also cost you a little power and mileage over a 190° thermostat.

 

[ranger 393]

As @Mikey-KE7LBB mentioned you will lose AC performance. You’d be better off to get a custom tune that will change the ECM fan parameters if you want it to come on sooner, but even then the stock temps aren’t an issue for most.

If you’re hitting 205° empty then the thermostat is likely the issue, or possibly a plugged/bad radiator. The last thing I’d consider an issue is the fan clutch. The fan isn’t programmed to come on until higher, ~215°, so it’s not a fan issue. While towing 205° is nothing. The thermostat isn’t even fully open until 207°, but an empty 5.9 shouldn’t be running anywhere near that.

Here in AZ some days the temps are pushing 115+-. The mechanical fan clutch engages at a lower temp than the stock clutch which will start cooling the temps sooner especially when towing. The radiator has been flushed and cleaned , new thermostat, new water pump..Since installing the mech clutch it has made a noticeable difference.

 

[AH64ID]

Here in AZ some days the temps are pushing 115+-. The mechanical fan clutch engages at a lower temp than the stock clutch which will start cooling the temps sooner especially when towing. The radiator has been flushed and cleaned , new thermostat, new water pump..Since installing the mech clutch it has made a noticeable difference.

AZ is the last place I would switch to a mechanical fan clutch. Your AC will suffer below 30-40 mph, and your top fan speed will possibly suffer too. There are good reason that they are not used anymore. Mechanical clutches engage based on radiator outlet temp, not coolant temp or AC pressure. You want a fan that works off coolant temp and AC pressure.

Even in 120°+ heat I never saw 205° empty on my 05. Something else is wrong if you are, and it’s not the fan. The mech fan clutch is just masking that issue now.

Your best option for cooling is the OEM fan with aftermarket programming if you want it to engage sooner. I modified the fan on my 05 to engage at 208° (thermostat full open in 207°) and temps never got above 211° after that. All while towing.

 

[Tuesdak]

A properly working OEM electronically controlled fan clutch can be full on in one block with a cold engine for A/C demand. The Obsolete Spring Thermal fan clutch is just that - depends on the engine to warm up as a cold radiator keeps the A/C heat away from the thermal spring in the fan clutch. After morning sickness wears off A/C suffers till the engine fan comes on from engine heat. Major problem in slow (under 45MPH) in town traffic.

In Arizona the Electronic Fan Clutch is night and day for A/C over the obsolete spring thermal garbage. It's like putting drum brakes back on. I have been told it takes 30 min for these obsolete systems to have full A/C performance. If you watch A/C high side pressures I bet you would be taking this mod off and demanding a refund.

Do you use high idle to keep the A/C cold in a parking lot waiting on someone? I do. The engine fan cycles quite a bit in a short time.

Others on 3rd gens have used electric pusher fans to help the A/C from blowing the relief valve as the ECM won't kick the compressor out on extreme system pressure. See windmilling restriction they are re: the main engine fan. It helps some, but, isn't enough to completely solve the condenser overheating problem when there isn't enough engine fan and the extreme high side pressure is ignored.

When you hit a grade at WOT the electronic fan can be coming on when the thermostat is opening up. The Spring Thermal Fan clutch waits till the thermostat is full open, the radiator is hot, the thermal spring warms up, and then the working fluid moves in the clutch: all while the ECT is running away. Each step has a specific amount of time it takes to warm things up or "do something" before the needed fan is locked in.

Having sent engines to the scrapyard from GM's poor cooling systems with Obsolete Spring Thermal fan clutches and co-developed a thicker Ron Davis Radiator for a TrailBlazer SS that uses an electronic engine driven fan clutch... This is a horrible obsolete change to make.

Matter of fact:

The ECM ignoring the high pressure in the A/C system till it opens the safety relief valve at 450+ psig for 3rd gens.

https://www.turbodieselregister.com...rams-ecm-defect-opening-the-ac-relief.258779/

And getting better performance out of the A/C with a coated condenser:

https://www.turbodieselregister.com...thermal-dispersant-on-an-ac-condenser.264486/

 

[Ozymandias]

All modern days Semis use a Vistronic Fan.

 

[Mikey-KE7LBB]

For me, the mod was cheaper than an OE replacement... That said, If I could've used a Horton instead, I would've jumped on that!!!

 

[Darkbloodmon]

Don't mean to drag up a dead horse but just wanted some quick thoughts on a Mechanical Clutch conversion. Got me thinking when I saw another Electronic clutch failure thread pop up amongst the others I've been following.

For reference I'm not concerned about A/C, hasn't worked since I got the truck unless at highway speeds and no wife or kids to complain. I've yet to take my dash apart and fix the vents/doors(they're all broken). I'm running a Mishimoto rad and Fleece coolant bypass with a broken(Chopped) OEM Mopar clutch on my early 03. No check engine light or limp mode like the later 04.5+ trucks; just A/C cycling. I've not had any cooling issues with the Mishi Rad or Fleece coolant bypass and they've done great for my payloads without a functioning clutch fan. But I'm planning some trips and may need to tow with payload.

Part list being a Hayden 2791 fan clutch ($45) and Motorcraft YA225 fan($100). $150 before shipping from "Rock your Auto" in comparison to buying the $200 adapter from the vid link in OPs post, and a $70 - $120 clutch to reuse the old fan.

 

[AH64ID]

I wouldn’t consider a mechanical clutch conversion if it’s came with a gift card to cabelas. It’s not worth it. The benefits to the ECM controlled clutch far outweigh the random issues folks have.

 

[Darkbloodmon]

I wouldn’t consider a mechanical clutch conversion if it’s came with a gift card to cabelas. It’s not worth it. The benefits to the ECM controlled clutch far outweigh the random issues folks have.

The efficiency of ECM Controlled clutch aside, I'm just interested in cooling under load without purchasing another OEM fan clutch only for it to get chopped.

I understand its better designed. But I just need something drop in reliable while crossing state lines.

 

[AH64ID]

The efficiency of ECM Controlled clutch aside, I'm just interested in cooling under load without purchasing another OEM fan clutch only for it to get chopped.

I understand its better designed. But I just need something drop in reliable while crossing state lines.

The OEM clutch is reliable. If you’re chopping wires you have another problem.

 

[Mikey-KE7LBB]

Cooling under load is not a problem at all! I've done quite a bit of towing my 30' 5th wheel all over the rockies, and it's pretty rare to see anything over 200° on the steepest of grades. I never got around to weighing the combo, but with a full freshwater tank, 3 full 30# propane tanks, generator with extra fuel, 60 gal aux tank, and toolbox full of stuff, I'm easily pushing close to 20k!

One thing I will recommend for the best cooling and A/C performance with the swap, is a genuine Cummins 180° thermostat. All of the major parts stores, and most of the online retailers will carry the exact same Motorad junk thermostat in a different color package. They are cheaply made, and the only time they run at the advertised temp is at idle!

 

[AH64ID]

Cooling under load is not a problem at all! I've done quite a bit of towing my 30' 5th wheel all over the rockies, and it's pretty rare to see anything over 200° on the steepest of grades. I never got around to weighing the combo, but with a full freshwater tank, 3 full 30# propane tanks, generator with extra fuel, 60 gal aux tank, and toolbox full of stuff, I'm easily pushing close to 20k!

One thing I will recommend for the best cooling and A/C performance with the swap, is a genuine Cummins 180° thermostat. All of the major parts stores, and most of the online retailers will carry the exact same Motorad junk thermostat in a different color package. They are cheaply made, and the only time they run at the advertised temp is at idle!

The 180° thermostat is a bad idea on anything with an electronically controlled fan that hasn’t been reprogrammed. The ECM uses ECT to program the fan and if you put a cooler thermostat in the truck you run the risk of running too hot without fan engagement. Even on mechanical clutch trucks is usually not a good idea to swap thermostat temps as the clutch fan is specific to the thermostat setting.

Each thermostat has opening, full open, and max allowable temps.

180°: cracks open at 180°, full open at 198°, and max allowable of 212°

190°: cracks open at 190°, full open at 207°, and max allowable of 225°.

The 3rd Gen 5.9’s don’t get the fan going at 100% until ~215°, which is above the max allowable temp of the 180° thermostat. This means that the engine isn’t rejecting enough heat if it gets to 215°.

The higher the ECT the more efficient the engine is too. The 190° thermostat really is the best temp for these trucks. It provides the best efficiency while maintaining a good oil temp at max load. The only good application for a cooler thermostat is a boat where there isn’t much airflow over the engine. Those engines generally use a 160° thermostat, but are programmed for that too.

 

[Darkbloodmon]

The OEM clutch is reliable. If you’re chopping wires you have another problem.

I know what the problem is, its not a mystery. I have a 20 year old plastic shroud that's cracked and damaged that I tried to piece together a while ago with zip tie stitching and gorilla glue and my quick fix cost me a $500+ OEM fan clutch.

I'm simply asking about the viability of a mechanical clutch conversion with the parts listed for my truck application.

I just need function, not OEM spec showroom perfection.

 

[Darkbloodmon]

Cooling under load is not a problem at all! I've done quite a bit of towing my 30' 5th wheel all over the rockies, and it's pretty rare to see anything over 200° on the steepest of grades. I never got around to weighing the combo, but with a full freshwater tank, 3 full 30# propane tanks, generator with extra fuel, 60 gal aux tank, and toolbox full of stuff, I'm easily pushing close to 20k!

One thing I will recommend for the best cooling and A/C performance with the swap, is a genuine Cummins 180° thermostat. All of the major parts stores, and most of the online retailers will carry the exact same Motorad junk thermostat in a different color package. They are cheaply made, and the only time they run at the advertised temp is at idle!

I'm pretty happy with my Stant 190* Superstat (PN:46289), Thanks for the feedback.