2008 6.7 fan not coming on

[Paul Wakefield]

2008 - 3500 HD- 6.7 - egr deleted. 285k miles.
Live in west Texas.
Daily drive
Could not hear the fan coming on, did the broom test and it was definitely failed.
I’ve always heard the fan come on in the past. Loud and clear.
Since the egr delete the engine runs much lower in temp. Never above the 200 mark.
Replace the fan clutch with a Mopar from Geno’s. Still not coming on.
Found the rubber seals on the thermostat were bad, changed it out with a Napa 190f.
Checked the fuse and it’s good.
Temp gauge shows right above the 2 on the 200 mark.
Also, now that the daily temps outside are hitting 90 degrees, if I drive over 70 mph when I get into town it will not shift into 5/6 gear. Thinking it’s the trans solenoid and valve body that needs upgraded. 68rfe
Any ideas on what next steps to take would be appreciated.

 

[Ozymandias]

Well, it's not supposed to come on until about 210f.
Full on at 220f or so.

And the ECM would also throw codes if it is malfunctioning.

To me I see nothing wrong with your trucks cooling system.

And please leave the broom stick away from that fan blade, it is a fragile part and if it explodes (because of micro fractures) the next time you hit an onramp it will be an expensive fix.

 

[Diesel85]

Sorry to hijack this, but @Ozymandias, I had a friend who accidentally left a box wrench on an idler pulley and they started the vehicle, and the box wrench caught the fan blade and it send it through the roof of his garage. It was both terrifying and funny, but after we looked at each other, we laughed our kahunas off.

 

[AH64ID]

2008 - 3500 HD- 6.7 - egr deleted. 285k miles.
Live in west Texas.
Daily drive
Could not hear the fan coming on, did the broom test and it was definitely failed.
I’ve always heard the fan come on in the past. Loud and clear.
Since the egr delete the engine runs much lower in temp. Never above the 200 mark.
Replace the fan clutch with a Mopar from Geno’s. Still not coming on.
Found the rubber seals on the thermostat were bad, changed it out with a Napa 190f.
Checked the fuse and it’s good.
Temp gauge shows right above the 2 on the 200 mark.
Also, now that the daily temps outside are hitting 90 degrees, if I drive over 70 mph when I get into town it will not shift into 5/6 gear. Thinking it’s the trans solenoid and valve body that needs upgraded. 68rfe
Any ideas on what next steps to take would be appreciated.

Scan for codes. The fan underspeed codes don’t always set a CEL.

What tune are you using?

I don’t think I’d trust a Napa thermostat in these engines, lots of bad reviews on any thermostat that isn’t Cummins.

The 190° thermostat cracks at 190° and is full open at 207°. The fan doesn’t usually cycle for coolant temp until 210°, depending on the tune. It should cycle lower for A/C.

 

[Ozymandias]

I wonder if he knows that the Fan isn't working the way it was, ON and OFF, but gradually just the amount the ECM calls him to speed up.
Most of the time the fan speed is below the limit for the driver to notice it being actually ON.

 

[Grumpy8811]

I wonder if he knows that the Fan isn't working the way it was, ON and OFF, but gradually just the amount the ECM calls him to speed up.
Most of the time the fan speed is below the limit for the driver to notice it being actually ON.

yeah, if you leave these trucks idling without that AC turned on, the fan barely freewheels.. only way many of us can even think to check fan operation under normal operation is to turn on the AC, and with the hood open you will hear audible changes in fan speed taking care of head pressure.

seems the way the engine is programmed it doesn't feed in much fan speed until that coolant is really hot, never figured out how hi the temp setting is to get full fan but its way up there.. probably 220F or so..