2024 6.4 Fan On @ Cold Start

[BowtechBob]

I'm sorry if this has come up previously. Brand new truck 700 miles on it. Fan clutch is engaged on every start. Sounds like a dump truck. Seems it stays on until truck gets up to temp. Also idles about 1000rpm until it gets up to temp. My 1500 will only idle that high for about 30 seconds.

Is this normal operation? Not a big deal, but I'd rather hear that big hemi than the dang fan.

 

[H3LZSN1P3R]

Is the A/C button on?

 

[MegaRed]

I think it's supposed to do that to put a little extra load on the engine to help it warm up. My 2014 6.4 did the same thing.

 

[oppizzippo]

Sounds like a dump truck.

You say this like it's a bad thing....dump trucks were my favorite tonka truck as a kid. What @MegaRed said is most likely. @H3LZSN1P3R has a good point, if you have defrost on it's running the AC compressor. For science someone should test this. Any YouYubers looking for video content????

 

[BowtechBob]

Thanks guys. AC/Defrost not on.

Sorry dump trucks are cool too. I just expected my truck to sound more like a Hemi. You know "blub blub blub blub" not "WHHHHRRRRRRR" LOL

 

[jharp]

The 6.4 truck Hemi has two fans. There is a conventional belt driven fan (coupled through a viscous thermostatic clutch) and a secondary electric fan (sandwiched between the engine driven fan and the back side of the radiator.)

Almost every vehicle with a thermostatic clutch fan has the clutch engaged during cold engine start. This is because the viscous fluid inside the clutch, when cold, is very thick, and tends to cause the clutch to 'lock up' and engage, until the engine runs a few moments and the friction inside the clutch warms the fluid up.

The high idle is to try and heat the catalytic converters up as quickly as possible. The catalyst inside doesn't function at all until it reaches a certain temperature, so the main reason the engine goes into high idle is to try and get the catalyst up to temp (and get the fuel injection system into closed loop mode quickly.)

 

[SolidAxleorBust]

One thing on my mind is, these trucks have way over built cooling systems (except the plastic parts on the radiator that explode LOL). So I will take a little noise for having so much access cooling.