Intermittent Roaring 2018 2500

[Ozymandias]

Good to hear that you made it home.
Please keep us updated how the dealer visit works out for you.

 

[Jdimig]

Disconnect the Shift motor at the TC and the shifter at the front axle. See if it still roars. Can't be good to grind these teeth all the time.

This will probably give some fault codes but better codes then...

What and where is the TC? Thanks.

 

[PaulFarkas]

Transfer case for 4 wheel drive

 

[Cummins12V98]

You don’t hear it work with the A/C? That’s at least 90% of the fan activation.

I start to hear the fan around 1000 fan rpms, and really hear it by 2000 fan rpms.

nope

 

[AH64ID]

nope

Interesting, you should be hearing it more.

 

[SnoKing]

Interesting, you should be hearing it more.

Only time I heard my 2015's fan was on a long hard pull with 15.5-16K of 5th wheel in tow.

 

[AH64ID]

Only time I heard my 2015's fan was on a long hard pull with 15.5-16K of 5th wheel in tow.

You should have heard it more often than that… maybe old ears? The A/C demands a lot from the fan.

 

[SnoKing]

You should have heard it more often than that… maybe old ears? The A/C demands a lot from the fan.

So my old ears only worked as altitude was being gained? Truck made 4.5 round trips from Washington to Arizona towing 5th wheels. So lots of ups and downs, and lots of warm weather in Arizona. Maybe the use of auto climate control, and not crawling around going slowly on back roads was in play.

 

[Cummins12V98]

You don’t hear it work with the A/C? That’s at least 90% of the fan activation.

I start to hear the fan around 1000 fan rpms, and really hear it by 2000 fan rpms.

Not a PEEP. My hearing is good even tho 35 years as a Carpenter.

 

[Cummins12V98]

When towing my Mobile Suites it takes climbing long grades before I really hear anything. When it does come on YES you do hear it!!!

 

[SnoKing]

When towing my Mobile Suites it takes climbing long grades before I really hear anything. When it does come on YES you do hear it!!!

Cabbage Patch comes to mind, because of the curves one is forced to go slower, thus less air force in from moving. I will beg going up it tomorrow morning.

 

[AH64ID]

So my old ears only worked as altitude was being gained? Truck made 4.5 round trips from Washington to Arizona towing 5th wheels. So lots of ups and downs, and lots of warm weather in Arizona. Maybe the use of auto climate control, and not crawling around going slowly on back roads was in play.

No, but the volume difference between A/C operation and ECT operation is significant. So it’s very possible to hear the ECT rpms and not A/C.

Not a PEEP. My hearing is good even tho 35 years as a Carpenter.

When towing my Mobile Suites it takes climbing long grades before I really hear anything. When it does come on YES you do hear it!!!

What you guys appear to be missing is that these fans are not on/off. They are modulated and vary in rpms based on ECT, A/C, Trans temp, and intake temp. The fan is likely always on, but often the airflow keeps the rpms above the set rpms so it's "on" but coasting.

When towing a grade and your ECT starts to climb the fan will really come alive, as high as 4000 fan rpms at 228°F, which is the peak. The fan starts out a modest 875 rpms at 207°. Above 212°F is where the rpms become noticeable as it works up from 1175 rpm to 2400 by 217°.

On the A/C side the highest the A/C alone will command the fan is 975 rpms, which is noticeable to me but still pretty quiet.

So unless you presume that both your trucks aren't working as advertised, unlikely, you simply aren't hearing the fan operate until it's rpms get higher and it's very noticeable, so I can assure you that your fan was operating a lot more than you think.

FWIW the fan programming in 2015 is identical to 2017 and 2018 (where I have most my 4th gen seat time), as is the fan itself. They all work the same, and thus will sound the same.

 

[Cummins12V98]

Not missing anything. I fully understand the fan ramps up as needed. Mine only makes audible noise when towing heavy in the mountains.

I run my AC all the time especially when in AZ and CA.

I guess me and SnoKing got the quiet ones.

 

[AH64ID]

Not missing anything. I fully understand the fan ramps up as needed. Mine only makes audible noise when towing heavy in the mountains.

You only hear it then, I’ll guarantee I’d hear it at other times.

Which is the point, it’s hard to claim something isn’t working just because you don’t hear it. Regen is the same, have you noticed one yet? Most the time I hear the engine/turbo noise change and then notice the active regen indicating on my insight.

 

[PaulFarkas]

Now back to our regularly scheduled program that is about the roaring in the drive train…..

Initial report from the dealer is the connection on the axle actuator. I got the truck in a day early which gave the tech enough lead time to have the part in by Friday.

Also the ACU for the brakes has crapped out for the second time.

Ozymandias, again thanks for you input. I’ll give a final explanation when I pick up the truck Friday.

 

[Cummins12V98]

You only hear it then, I’ll guarantee I’d hear it at other times.

Which is the point, it’s hard to claim something isn’t working just because you don’t hear it. Regen is the same, have you noticed one yet? Most the time I hear the engine/turbo noise change and then notice the active regen indicating on my insight.

Didn't say it's not working I said I can't hear it in conjunction with just the AC. My hearing is just fine.

Don't care about re-gens.

 

[kthaxton]

I hear mine with my AC, it mostly stands out when I first fire up the truck with the AC on and the engine cold.......the first few times, I thought, why is my fan on already, the engine isn't even up to temp....then I realized, oh yeah, AC.

 

[Cummins12V98]

Guess I am just lucky. Fill to only the top of safe zone, change ALL my trans fluid, filter from the top, diffs to bottom hole, never hear fan with just AC, never notice a re-gen and that goes on.......

 

[kthaxton]

My hearing is just fine.

That's what my wife has been saying lately.......She insists I am talking quieter or mumbling.....yeah, cuz that's what happens when you get older......you talk quieter, hearing doesn't get worse as you age! Silly talk I say!

 

[EZeis]

My 2018 didn't make noise but I would get 4wd shifting in process randomly. Turns out it was a bad transfer case switch making the system think I was shifting it in and out of 4wd. Dealer said it was a common issue and the switch was on backorder for a while. Mine is manual shift 4wd.

I agree with others. The AC will definitely spin the fan up when needed. Especially if you're parked and have it on idle up. It will roar pretty good. Most of the time I hear my engine fan is from the AC. Gotta be a long grade with my 13k trailer on to get the engine coolant temp to drive the fan rpms.


Earl