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Fan Clutch Problems

24K views 27 replies 8 participants last post by  Classix_Lover 
#1 ·
Bought a standard thermostatic fan clutch setup from summit quite a few months ago and it's been sitting for some time. Finally got around to installing it with an OEM fan. Whenever it engages, it's supposed to run at 70% of the engine's rotational speed. I tested it without a shroud first to see if everything was working properly and what a surprise, I don't think it is. I took it around the block for a good 20 minutes, parked the el camino in the garage and let it idle for a good while. Shut it off, grabbed a fan blade and attempted to turn it and.. what the hell? The fan's turning relatively freely, not resisting being turned like what it's supposed to do when engaged. Cranked it up again, let it get to 220 and then shut it off. Again, still offering very little resistance. This is a load of bull. Defective part or is this really what it's supposed to be doing? The fan is no more than 1" away so it's plenty close to absorb the heat properly. I'm guessing it's a defective part. I don't want to go through the trouble of sending it back to summit and have it go through warranty check and wait for god knows how long just to get another one that might be defective as well. I'm not very happy but at least I fixed the leak from my radiator.
 
#27 · (Edited)
Classix_Lover said:
Ok, here's the deal. Got another fan clutch, heavy duty this time, Hayden brand.

, everything spun true and of course massive cooling improvement at higher speeds compared to the other mediocre electric fans.

Once again, let it idle for a good while. Shut it off and imediately grabbed the fan blades to spin it and whaddya knowwww! The damn thing is STILL freewheeling and not properly locking up.

.?

First, you don't need a fan above 30 mph, so it shouldn't make any difference. If it made a difference it is probably because the electric fan was blocking the airflow.

Second, you don't know how hot the air is going across the fan clutch.,,,,,

because.....

Third, the fan clutch is so close to the radiator that air cannot flow across it readily, so it might not be working correctly. 1 1/2 inches minimum clearance is needed for airflow. :thumbup:

Fourth, you are probably going to have to use a Derale stainess flex fan with 2 1/2 inches pitch and make a shroud, since a factory shroud will be too long and not match to your blade position. The blade should only be 3/4 inch maximum into the shroud.

http://www.derale.com/heavy-duty-flex-fan.html

Actually I don't think you will need a shroud if you use a high pitch Derale fan blade 3/4 inch from the radiator. I didn't.

I can hold my hand 10 inches in front of the radiator and feel the air pulling in with the engine at idle. I have never had a problem at 100+* and idling with the AC on. No shroud.

Sorry I missed your picture earlier....... :spank:
 

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#28 ·
xntrik said:
First, you don't need a fan above 30 mph, so it shouldn't make any difference. If it made a difference it is probably because the electric fan was blocking the airflow.

Second, you don't know how hot the air is going across the fan clutch.,,,,,

because.....

Third, the fan clutch is so close to the radiator that air cannot flow across it readily, so it might not be working correctly. 1 1/2 inches minimum clearance is needed for airflow. :thumbup:

Fourth, you are probably going to have to use a Derale stainess flex fan with 2 1/2 inches pitch and make a shroud, since a factory shroud will be too long and not match to your blade position. The blade should only be 3/4 inch maximum into the shroud.

Also, I'm not sure about your theory of airflow not properly getting to the clutch.
http://www.derale.com/heavy-duty-flex-fan.html

Actually I don't think you will need a shroud if you use a high pitch Derale fan blade 3/4 inch from the radiator. I didn't.

I can hold my hand 10 inches in front of the radiator and feel the air pulling in with the engine at idle. I have never had a problem at 100+* and idling with the AC on. No shroud.

Sorry I missed your picture earlier....... :spank:
Dude... when I said I noticed a massive cooling improvement when moving, I meant I could easily see how the belt driven fan would help bring the temperatures down much faster compared to the mediocre electric fans. It's obvious that mass airflow past 30 mph should be more than adequate to cool it, I wasn't questioning that.

And no, I'm not going to get a flex fan. I don't care for them whatsoever. What's to stop me from fabbing up a shroud in the first place? I already mentioned numerous times that I'm building it up from scratch; I'm not searching in the junkyard for one to make it work.

Also, I'm not so sure about your theory about the clutch not getting proper airflow to it.
 
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