Loud Fan??? 05 Sierra HD Duramax

[js05sierraHD]

Anyone know why my fan seems to get EXTREEMLY loud????? I tried to pinpoint what i am doing when it happens but its pretty inconsistant...

Sometimes it starts out loud and if i hammer the gas it goes away other times it doesnt stop. Usually it disapears by the time i hit 3rd or 4th gear.

Occasionally it dissapears shortly after it starts and other times it seems to never end. It always ends.

I've tried switching into [N] Neutral and back to [D] even to [3] or [2], but nothing helps... Only time seem to make it stop....

Got any ideas........

[climber58]

Mine does the same thing, but only when I am towing through repeated hills....Is it the tranny cooler?

[sherman69]

Thefan gets noisy when the engine is hot.
The air coming through the radiator heats the control that tightens up the fan clutch that the fan is mounted on. Then when it is cooled down, it loosens the clutch.
If it is happening when it is cold, the fan clutch must be failing.
Mine only does it when towing in the mountains for a short time.
Bob B

[js05sierraHD]

Hmmm... It usually happens on hot days... 80° F +, and around 200° F Tans Temp... (I don't tow but do drive consistantly at 75-85 mph) What is the normal operating temp of the Allison on a hot day???

I installed a DENALI style grille could this be preventing cold air flow to cool the radiator?

[js05sierraHD]

Originally Posted by js05sierraHD

Hmmm... It usually happens on hot days... 80° F +, and around 200° F Tans Temp... (I don't tow but do drive consistantly at 75-85 mph) What is the normal operating temp of the Allison on a hot day???

I installed a DENALI style grille could this be preventing cold air flow to cool the radiator?

Well after talking to a service tech at my dealership, i'm thinking it is the grille. Oh well not a big deal... it hasn't happend since the temp has dropped so i guess i will just deal once in a while.

[SteadFast1]

my 1980 gmc, has a 350, and the fan is very noticable at idle, and sometimes towing. the fan is not an electric one though i would like to install one.

my mom's van's fan(electric) is squeakie when its moist or wet outside, it could just be the humidity

[SpeedTherapy]

These motors have a clutch fan that will sometimes engage when first starting out for a short distance. They make a lot of noise. For the most part, it will only engage when airflow through the radiator is insufficient to cool the motor. Duramax, huh? Anybody with this engine has to check out this forum: dieselplace.com. Sit back, read, relax, spend money, go fast.