Community Forums

triker08 · 06-24-2016, 07:13 PM

I have a 2005 Newmar Mountain Aire with the Chevy 8.1 engine. While cruising down the road I hear what sounds like a different noise that sounds like the engine is revving up, but the tach doesn't move. Then after a minute or so the sound goes away slowly, as it started. Is this a fan for the transmission? I have the Allison tranny btw.

LarrytheBear · 06-24-2016, 07:21 PM

I believe you are right. My 8.1 does the same thing.

triker08 · 06-24-2016, 07:27 PM

Thanks. The noise doesn't come on as often if I turn off the dash AC. I had a 2000 MH with the chevy 454 I think, and it did the same thing.

LETMGROW · 06-24-2016, 07:39 PM

What you are probably hearing is the temperature controlled hydraulic fan clutch engaging and disengaging. The rush of air through the AC condenser and engine radiator can be noisy under a load. This is normal.
Lynn

CharlesinGA · 06-24-2016, 08:21 PM

Sprinter Chassis motorhomes are very noted for this. The noise is quite apparent, and coupled with a marked drop in engine temperature before the fan shuts off.

Charles

RodK · 06-24-2016, 08:32 PM

Quote:

Originally Posted by LETMGROW

What you are probably hearing is the temperature controlled hydraulic fan clutch engaging and disengaging. The rush of air through the AC condenser and engine radiator can be noisy under a load. This is normal.
Lynn

+1 it will be the fan. Normal

vettenuts · 06-25-2016, 05:00 AM

Yes, and I find the same. Using dash A/C makes it happen more frequently. One thing I will say, the system as loud as it is seems to work well when climbing those long hills.

mpierce · 06-25-2016, 05:13 AM

Even if the engine does not need the cooling of the fan, using the A/C does. You need more air to remove the heat from the A/C system, so the fan kicks on.

speed racer · 06-25-2016, 05:55 AM

On my 04 Workhores chassis I have what is known as the cool pack. When you turn on the chassis A/C the two fans in front of the radiator come on. This also helps cool the radiator so the fan clutch doesn't engage as often.

litlgeezer · 06-25-2016, 06:08 AM

Your fan clutch is working to cool off the engine as designed. After a steep climb onto a plateau in New Mexico last August, I had a water hose burst while on our maiden trip. I was unfamiliar at the time with a fan clutch. The Las Vegas Diesel Repair mechanics repaired the broken hose and replaced the fan ($450 fan and $100 lbr) and we were back on the road. Several miles down the road, the clutch engaged and it took me several agonizing minutes to realize that it was the new fan clutch doing it's job. It comes on at varying speeds and can sometimes be a little noisy, but I will take the noise any day, rather than an overheated system.

Gary RVRoamer · 06-25-2016, 01:28 PM

That's a Workhorse W-series chassis, so those are probably the electric cooling fans rather than the engine driven one. They sound like a jet revving up when they come on! So yes, that is normal. The engine computer (ECM) turns them on when it detects extra cooling is needed.