I have 03 Dodge 3500 Cummings with the electric fan clutch and fan that looks like it belongs on a big rig. Question is can I replace that with conventional fan clutch without any side affects and if not what are the side affects.

 

DIESEL ENGINE
The electronically controlled viscous fan drive is attached to the fan drive pulley mounted to the engine. The coupling allows the fan to be driven in a normal manner. The fan speed is controlled by the electronic control module.
5.9L DIESEL
The Engine Control Module (ECM) controls the level of engagement of the electronically controlled viscous fan clutch by monitoring coolant temperature, intake manifold temperature, air conditioning pressure and transmission oil temperature. Based on cooling requirements, the ECM sends a signal to the viscous fan clutch to increase or decrease the fan speed.

Fan speed is monitored by the ECM. Fan speeds above or below a calibrated threshold will set a DTC. Circuit concerns will also set fan clutch DTC's.


So I would not advise changing it. There are companies that make what they claim will work, but the factory fan clutch does a really good job..

 

The 03's and 04's should have a mechanical fan clutch.

The 04.5+ trucks have the viscous fan clutch that the ECM sees.

On the 03 & 04, you should be fine. On the 04.5+ trucks, you can replace it with an electric fan, but it will set 2 soft codes. It won't trip the CEL and it won't have any negative effects on performance, but those codes will be there.

You'll need either a 34 or 36 mm fan clutch wrench to remove it.

Any of the auto stores that loan the tools should have it.

 

you say that they didnt put the viscous fan on until 04.5 models can you explain why my 03 has it on there. I also heard it will effect the shifting of the truck is this true. thank you for the info I am trying it as of now with a mechanical fan clutch.

 

Is yours a 260HP SO or 305 HP HO model? The SO will have the mechanical, the HO will have the viscous.

There are two different part numbers.

From underneath the truck, look up on the drivers side of the fan clutch and look at the wiring that goes to it.

The mechanical clutch will only two wires that control it for either engaged or disengaged. The ECM does not monitor this one.

The viscous clutch will have 4 wires running to it. This one is controlled and monitored by the ECM.

Either one can be replaced with the electric fans and will have no ill effects. BUT, the models with the viscous fan clutch will set two soft codes in the ECM. These codes will not trip the CEL and will not degrade performance.

The flex-a-lite fans you'll want should be model #264.

 

Coal Train I thank you, you have been a great help in this matter. I have the 305hp HO cummings because I have 4 wires coming from the fan. I have installed an conventional fan clutch and fan on my truck and have seen no difference in performance nor has it thrown any codes. I used fan and fan clutch off early model cummings that has no wires to get in the way. Thank you for your info.