My clutch fan on my recently aquired 99 Blazer makes a roaring sound when its hot outside, in other words the fan is not disengaging, I have put 2 new ones in (including a new from GM) and is still sounds loud. The fan itself has 11 blades and looks to be straight, The garage that did the work is baffled any[&:] ideas out there?

 

that does sound weird.....

I know mine is pretty loud when i first start the car up. But once i go up the big hill out front of my house its seems to stable out...

Not sure bro Maybe its meant to do that to help cool the engine more? i dont know

 

The more the fan is working, the louder it will be. My dad puts on a heavy duty fan clutch in the summer time on his work truck. That thing roars REALLY loud.

Mine roars more when the temps are high outside and it really is a normal thing. Did your old clutch roar and was that the reason for replacement?

*EDIT* - also, something else I thought of. Is your truck a 4wd? If so, do you still have the the plastic air dam (should have an access door for the remote oil filter)? If not, it is possible that even though your engine temps seem normal, due to the pressurization of the engine bay from behind the radiator, you could have some air flow problems causing the fan to stagnate.

 

My truck is a 4X4 and the cover for the oil filter is in place, I bought this Blazer used and the fan has always been loud when its hot, I replaced the clutch fan for this reason perhaps a waste of time?

 

mine does the same thing but only when its hot out...im guessing just working harder to keep the engine cool

 

My last truck was a Jeep and it had a electric fan, it wasn't as noticable as this clutch fan, my truck was overheating while idling I guess thats why I thought something was wrong, turned out to be a plugged rad

 

that has me thinking i have a 95 2wd 4.3 vortec and my fan dose that when its hot but if i turn the ac on it dose it all the time

and another think i have notaced a ratteling noise comming from under the blazer at idel and it rattles more when i have the ac on(i do have a low idel about 650 rpm

anyone know what this is?

 

It is normal. Mine does the same thing when its really hot out, or if I idle for longperiods of time in above average temps, and turning on the a/c unit increases the frequency. Typically this will happen during around town driving in hot weather as well.

The fan is trying to keep the engine cool. Be glad its happening, the alternative is overheating.