Recently I had my thermostat replaced, clutch fan, and finally my radiator as my 03 Blazer started to run a high temperature. My old clutch fan used to run very loud in first gear when its primarly hot. The new fan runs excessively loud and continously, often times through multiple gears. It has been blazin hot here in TX, but when the AC is off, the clutch fan does not run at all that i can hear. Even at highway sppeds I can hear and feel it running at times. Lastly, even with a cold start, it kicks on and sounds like a diesel big rig. Any suggestions?

Pete

 

Well, after going through two clutch fans, I would have to say its the clutch fan. I brought a heavy duty clutch fan from auto zone with a life time warrantly (sp) When I would 1st start up in the morning it would sound like a train coming at me. I thought hey its a Heavy Duty one, and not the OEM one that had went out (I have a 2000 4x4 4.3 LT Blazer). It lasted about 6 months. I was at the Phoenix AZ airport dropping my wife off and notice the heat gage getting higher and higher and no rushing sound from the fan, I said oh crap, I'm 70 miles from home..Now what? So as soon as I got away from the airport, I pull over and let the pressure off the crap and let it cool down (Had a smoke or two), then roll down all the windows cut the A/C and started out (It was 110 degrees that day, so not a "Cool" ride home). But I made it with the temp staying around 220 or so, but if I kick the A/C on it would shoot up so I left it off and just sweated a lot..hahahahaha...Took the Clutch fan back to auto zone and they gave me another heavy duty one for free. Put it on and everything has been fine since (Over a year now) and this fan is not as loud as the other one was and its a heavy duty one also. I must have just got a bad one before. My temp reaches around 205 then it kicks in and holds it there pretty good concering living in the AZ desert. And no more morning rush sound either, well mabye a little but now train sound...whoosh.

 

Thanks Dennis. When my temp started to rise for the fisrt time in 2 years, my mechanic went for the thermostat first. While idling in the shop it seemed fine, but after 10 minutes on the road the temp began to ride. Next solution was the clutch fan. Again, that seemed to solve the issue in the shop, but 20 minutes on the road and the creeping began. Solution, Radiator. Great, no problems since, except for the train that greets me each morning and anytime the AC is on, its hot outside.

 

Fan clutches are actually designed to allow different amounts of slip depending on application. When it needs to cool, the clutch engages. But it wont be a solid 100% engagment. There will still be some slip. The amount of slip is determined by its application. Standard duty may be 35% slip. Towing package may be 25% slip. Heavy duty may be 15% slip. (These nembers are just examples.) Less slip means more air movement. More air movement means more noise.

So if you purchased a heavy duty clutch for a vehicle that wasnt equipped with one originally, you will here alot more noise since the clutch is actualy operating differently.

 

It has been my experience that aftermarket fan clutches suck. I went through several on a compact truck I used to have when the original bit the dust. I even tried a few brands and it was the same result. Unfortunately the original was over 400 bucks and at that time I just didn't have the cash so I added an aftermarket flex fan and the "running hot" problem disappeared. I would go get a factory fan clutch either new or at the boneyard the aftermarket ones just don't seem to work well.

 

The clutch fan is a dime a dozen at the boneyard as one guy put it. But mine hardly ever runs unless I drive a long distance then come to a stop and take off again slowly, then you can hear it run for just a moment in 1st and 2nd gear then you might not hear it again for a while. I guess what Im triing to tell you is that mine does not run very often at all or it runs very quiet most of the time

 

I would have to agree with the comment about after market clucth fans, so its wise to get a life time warrantly with them, they go, you go get another one free. Labor intense but better then buying one from any where. I also have replace the thermostat, rad, then the clucth fan. Its still gets up close to 210 all the time (And have the rad flushed) and sometimes over that, but living in AZ where it get to 115 everything runs a little hot. Days are getting cooler now, so all will be alright.