Corvette Forum : DigitalCorvettes.com Corvette Forums banner
1 - 10 of 10 Posts

·
Registered
Joined
·
152 Posts
Discussion Starter · #1 ·
The PO installed a new fan clutch about a year ago, Put less the 500 miles on it and at highway speeds it sounds like a tornado.

I am really not use to this and it makes driving on the highway very uncomfortable.

I notice when I get back in garage hot or cold the fan doe not freely spin it is very stiff on the clutch.


Whats normal?
 

·
Registered
Joined
·
910 Posts
The fan clutch engagement is controlled by the temperature of the air that has passed thru the hot radiator. The hotter the air, the more solid the engagement.
It depends a lot largely on the ambient temps too.
Here is S Florida, this can commonly happen, but late evenings whens temps are lower, the engagement and noise should be reduced.
You also may have a poor quality or defective clutch.
They also degrade over time, but that would make it spin less with less noise.
Try running the engine for about 2 minutes from cold, shut it down and then the fan should spin a lot more freely by hand.
 

·
Registered
Joined
·
2,948 Posts
The coil spring on the front is essentially what controls the clutch's engagement. As the temp rises the coil contracts and turns the shaft engaging the clutch.

There isn't really any adjustment built in but I have played with different springs from different clutches I had laying around to find one that best suited the application.

When the engine is hot and been at operating temp for a while, pop the hood, turn off the ignition, and watch how many times the fan spins. Basically, if the coil and clutch are working properly, it shouldn't spin more than 1 or 2 full revolutions. If it spins more than that then it's not engaging properly at engine temps.

If it stops promptly, then the clutch is engaging.

At the same time, with the engine cool and after it's sat say overnight, manually turn the fan a few times to loosen the fluid and then see how easily the fan turns. It should loosen and easily spin several times just with finger pressure. This means the clutch is disengaged as it should be when it's cold.

If the fan is hard to turn even when cold then the clutch is always engaged. You might need a new spring, or a different application clutch.
 

·
Registered
Joined
·
1,137 Posts
Improper storage position (ie not kept vertical, as it is when installed) for an extended period of time (sitting on a shelf at your local AutoZone) can mess with the fluids and cause these symptoms.:down:

Solution: New fan clutch.:thud:
 

·
Registered
Joined
·
552 Posts
If the PO bought a $75 premium heavy duty fan clutch, that's what they sound like. Especially when used in passenger cars with fans that don't have as much air resistance as larger truck fans.
 

·
Registered
Joined
·
1,523 Posts
I have a severe duty one made for taxi and police cars. I haven't noticed any difference in sound between it and the factory one when engaged (that maybe just me). I modified mine by drilling the pilot hole to the proper 3/4" size. By the way the severe duty keeps mine at around 160 degrees on a 100+ degree day that we southerners get here during summer months. Get 'er fixed and back on the road soon:thumbsup:
 

·
Registered
Joined
·
332 Posts
MY79 hub started to leak which made it freewheel to easily at low revs hence overheating with a/c on. Was able to get a hub off a 77 big block(severe duty??) with 7 blades on it,and boy did it roar,took off the 7 blade to fit my 5 blade and its nice now. Can still hear a dull roar when i step on it.:thumbsup:
 

·
Registered
Joined
·
84 Posts
I have an Eaton replacement fan clutch that does have an adjustment on it. On the front there is a bracket with 2 slots where a tab on the bi metalic coil fits. You can change the clutch operation by moving the coil tab to the empty slot.
 

·
Registered
Joined
·
152 Posts
Discussion Starter · #10 ·
I purchased a 34 dollar clutch from my local old time parts store and it works perfectly.

I also closed the gaps around my radiator and condenser coil and that absolutely fixed all my heating/cooling problems.

in 100 degree stop and go traffic it will get to 220+ then the the electric fan kick in and cools it back down to about 205-200.

At the peak of the day road temperature, meaning I measure outside of the car near my front scoop the incoming air is 115-120 degrees.
 
1 - 10 of 10 Posts
Top