Watch this video and tell me what you think. Take note, there was about 14k behind me pulling a long grade. WOT and the engine temp starting to climb. There is no engine fan roar but as soon as I let up on the throttle you can hear the engine fan come to life and everything cooled right down. It was about 90*F outside too...

I'm wondering if the fan clutch is getting worn out or is there something else going on I'm overlooking.

 

 

That's the trouble with the oem temp gauge, it is hard to tell what the temp really is. A guess might be 10* off. If you were at 210* all is well, if you were 220*, then, yes it is a little warm. I assume you are running the oem 190* t-stat? Is it a Cummins stat?

 

My clutch comes on at 208* with a Cummins 180* stat, I really like the 180. Everything associated with the engine is running 10* cooler. Fuel temp, IAT, even the transmission. Prior to, I was having all kinds of overheating issues. I used 180 and 190 aftermarket, they were terrible. It cruises at 183* seems to close at 177* and opens about 187* I have a CTS monitor with digital gauges.

 

Does your clutch come on at low speed/rpm, such as in town with the AC on? 

 

Your truck sounds good, boost and EGT's mirror mine on level 2, tow mode, same as EZ.

Yup. 208F to 212Fwhen mine locks the fan. Been like that for 17 years.

Just remember that the max allowable temp, from Cummins, for a 180° thermostat is 212°. If you're getting above 212° the heat rejection capabilities of the cooling system are inadequate... this would most likely be due to the fan settings if the OE thermostat was 190°. 

46 minutes ago, AH64ID said:

Just remember that the max allowable temp, from Cummins, for a 180° thermostat is 212°. If you're getting above 212° the heat rejection capabilities of the cooling system are inadequate... this would most likely be due to the fan settings if the OE thermostat was 190°. 

 

Where did you read this?  Do you know what the 190* rejection capabilities are?

4 minutes ago, KATOOM said:

 

Where did you read this?  Do you know what the 190* rejection capabilities are?

 

I've read in on quickserve. 

 

180° thermostat is full open at 198° and max allowable 212°

190° thermostat is full open at 207° and max allowable 225°

 

Now you can see why the fan kicks on around 208° with a OE 190° thermostat

Edited July 10, 20195 yr by AH64ID

3 hours ago, AH64ID said:

Now you can see why the fan kicks on around 208° with a OE 190° thermostat

Yup that's about right. Being the fan has to sense the heat from the radiator to get the thermostatic coil to twist the clutch to lock up. If the Radiator is shedding heat then the fan will lock. If the thermostat is close or barely open the face of the radiator is rather cool to the touch not enough heat to lock. 

 

As long as the fan lock around 205 to 210 your good. 

 

3 hours ago, AH64ID said:

190° thermostat is full open at 207° and max allowable 225°

 

That is the high normal mark on the gauge.

Just wanted to update the thread that I have determined that the fan clutch is working perfectly fine.  I've been towing in some much hotter weather we've been experiencing these past few days and the engine fan is roaring just like it has always at the appropriate times.

Thank you everyone for the suggestions and input...