Fan clutch?
 

Can someone explain exactly how the fan is supposed to work? Well I know "how" it works mechanically just curious if mine is doing what it is supposed to. I have been obsessing with temps ever since I got this thing.:-arrgh Recently while towing about 7,000lbs my ECT was hanging out in the 214-220 range. Once I believe it hit 224 pulling a little grade.. I could hear the fan come on but it was always just for a second. It never spun up and stayed on for any length of time. Just as soon as it spun hard enough to hear it, it would quiet back down. I would think it would run longer than that. Am I correct or is this exactly what it's supposed to do? Had the AC on the entire time and ambient temps were 98*-99* and speed was 60MPH
Are these temps anything to be concerned with while towing? My EOT never exceeded 238 and that was at the ECT peak as well. Cruising along the ECT probably averaged 216 and the EOT about 230. Unloaded street cruising - ECT 188-192 EOT 195 - 202
Its a good thing I shave my head cause if I didn't I would have pulled it all out over this thing!! :-huh

Do you have your EGR valve still plugged in? IIRC a member tech (cheezit) found out that the valve needed to be plugged in for the fan strategy to operate properly (at least for some year models).

Engine temperature is not the only parameter that the PCM monitors to determine cooling fan operation. This is the reason that you will see some variation in engine temperature as it correlates to fan operation. The operation/description of the FSS (Fan Speed Sensor) from the PC/ED manual has a fairly good explanation as to how the system "thinks". This is not your traditional engine hits temp X and the fan clutch locks up.

The fan speed sensor is a Hall-Effect sensor integral to the vistronic drive fan (VDF). The powertrain control module (PCM) will monitor sensor inputs and control the VDF speed based upon engine coolant temperature (ECT), engine oil temperature (EOT),transmission fluid temperature (TFT) and intake air temperature (IAT) requirements. Also, the air conditioner high side pressure switch will cause the fan high speed to activate (ACP V). When an increase in fan speed for vehicle cooling is requested, the PCM will monitor the FSS signal and output the required pulse width modulated (PWM) signal to a fluid port valve within the VDF.

At least one person has seen the factory gauge go from normal to the "red" quickly. It happened around 240 degrees F.

Also from the PC/ED manual:

The dual function pressure switch (DFPS) is used to interrupt A/C compressor operation in the event of high system discharge pressures.
The dual function pressure switch is mounted on a Schrader valve-type fitting on the high pressure side of the compressor manifold and tube assembly.
A valve depressor, located inside the threaded end of the DFPS, presses on the Schrader valve stem.
This allows the DFPS to monitor the compressor discharge pressure.
The DFPS has two sets of electrical contacts. One set of contacts is normally closed and is used for A/C high pressure cutoff.
When the A/C compressor discharge pressure rises, the switch contacts open, disengaging the A/C compressor. When the compressor discharge pressure drops, the switch contacts return to the closed position, and A/C compressor operation resumes. For specifications regarding operating pressures, refer to Section 412-00.
The second set of electrical contacts in the DFPS is used for engine cooling fan control.
It is not necessary to recover the refrigerant to remove the DFPS.

EGR is clean and plugged in. Went over that with the recent oil cooler change. It is also working according to Forscan.

Was the A/C on? Have you noticed a difference in cooling with it on vs off?

Are you monitoring your fan speed? I do not have my EGR valve plugged in but if my coolant temp gets to 210 and is not almost immediately on its way back down my fan clutch will lock up. If the AC is on it will come on at a lower coolant temp depending on the circumstances. When it locks up the fan speed is significantly higher than engine speed.

A/C was on and honestly I never thought to turn it off and see if it effected anything.

I do monitor fan speed and it does fluctuate. Haven't watched it real consistently so I cant say much about what it's doing but it does change. I just thought once the temp. got high enough for the fan to lock up it would stay on more than just a second. I would assume it would stay on until the temp dropped 5 or 6 degrees.

Don't forget that BIG open front @ 60 MPH is very effective at directing air in for cooling.
Just as a normal maintenance step I would check all the cooling fins for bug, leaves and mud.

While you’re monitoring make sure that when it does lock up the fan speed should be significantly higher than engine speed. If memory serves when mine is locked up and engine speed is 1500rpm the fan speed is over 2000rpm. If yours isn’t doing that then your fan clutch may be no bueno.

My 03 has been behaving exactly the same way. No egr and running with the ac on. Temp has been around 90 outside and my camper is around 10k. Running flat its been right around 212ect, 218ect. On the hills in pa and maryland it topped out ect 225, 230eot. Im running a mishimoto rad and a dieselsite billet water pump. I have no idea if its normal or not but thats what its doing according to my sct x4. Tune is stock.

Once you have deviated from the stock configuration then a lot of the standard numbers will no longer apply.
You are then going to have to learn how your truck/Ex behaves and base things from that. This also includes
any tuning that you have on that is not stock. Something to do when you know that things are right is to make
note of all the given data and use that as your baseline.

Sean how do you feel about mods like a 7.3 clutch on the 6.0?
Tim

I personally don't care for it. There are simpler ways to get the same results.
All you need is a switch and a little wire.

OK- I was asking more if there was any reason not to modify the existing 6.0 clutch.?