Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bigdaddy89, Mar 18, 2001.
How do I know if my clutch fan is working correctly or if it is bad? 1989 350fi AT .
Usually, and i use the term loosely, You will have a vibration from the engine. You will have to trace it back to the fan.
To check if mine is still OK I will let the car idle up till hot switch off the engine and rotate the fan by hand, you should feel resistence, if you don't double check your engine temp, make sure its above what the fans rated engagement temp. If this all checks out then your viscous clutch is stuffed and needs replacing. Happy trails.
It heated up on me yesturaday, and when I got out and checked it, there was no resistence. This must be my problem.
Sounds like it. The only thing I would like to add to what "belly" said is that you should heat it up with the hood closed. This is because the clutch is controlled by a bi-metallic coil in the front. If you leave the hood open, the ambient temp in the engine compartment may not get high enough to tighten it up when the engine temp indicates that it should.
Anyway, sounds like you were driving it when it over-heated so this should not be a problem. With it hot, if you can move it without it feeling like it is moving in cold molasses, the clutch is almost certainly your problem. Remember though, it is a viscous coupling so it will not be really hard to turn. However, if it were working correctly, I really don’t think you would describe it as “no resistance”.
85 K30 CUCV, 350 TBI, TH400, NP205, D60/C14, 4.56
Coming soon: 4" lift, 40" tires, massive cutting, shorter wb and rear overhang.
If the clutch is working, you'll should be able to hear it engage once the motor gets hot enough to activate the coil. The fan will start to "roar" and should stop "roaring" once the fan has cooled the motor down enough to disengage the coil. The sound is unmistakeable- it almost sounds like your tranny is stuck in 2nd gear.........
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I thought that the clutch fan on my S-10 had failed a few years ago. When I took it off to replace it, I noticed that the bimetallic spring on the front of the clutch was caked with mud. I washed it out good and it's been working fine ever since. I don't know why they didn't put some type of cover over the spring.
<font color=black>HarryH3 - '75 K5</font color=black>
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I put a flex fan on mine. It doesn't use a clutch. My new blazer came with one, yea! They are kinda loud, but the noise could be mistaken for a super charger. For a long time everyone around town thought this camaro had a supercharger on it and he said it had a flex fan on it.
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HarryH3, I think if they put a cover over the bimetallic spring it wouldn't sense the temperature anymore.
If you find out that yer clutch fan is bad pitch it, there expensive about $35 plus they have a habit of going bad at the worst time like 20 miles of low range driveing from any where. Jeff 80blazer
Its time to lock them in!
All the ones I have had, if you pop the hood, you can HEAR the fan as the vehicle starts...most of the clutches use both the coil AND silcone(?) to lock up (thats why the fan is on when thevehicle starts)..thats what the "gunk" is that you typically see at the coil..leaking silicone. Once the engine has been running a few seconds, and the silicone has heated up and become more viscous, the fan will stop being "locked up" I'm sure this isn't a positive ID if its bad or not though. You can also check for play on the fan clutch shaft.
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