Can you test a fan clutch in the oven? - Team Camaro Tech
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post #1 of 13 (permalink) Old Jul 26th, 17, 11:43 AM Thread Starter
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Can you test a fan clutch in the oven?

This might get the wife yelling at me, but would putting my fan clutch in the oven and heating it up to around 225* tell me if it is still good? I am putting a clutch fan on my otherwise stock L35 396 to help with low speed airflow, and I have a couple of fan clutches I would like to test. I purchased a new one from NAPA, but I am not crazy about the generic aftermarket ones that everyone sells that have the slots for the universal bolt pattern. Would prefer more of an original look, but also don't want to spend a couple hundred on a correct reproduction, since I am not even sure that this will correct my problem.

Seems like if I heat it up to the temp where it is supposed to "lock up", I should be able to tell a difference in the effort it takes to turn it compared to when it is cool. Has anyone tried this?

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post #2 of 13 (permalink) Old Jul 26th, 17, 11:48 AM
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Re: Can you test a fan clutch in the oven?

Rather than an oven that can get to a temp a lot hotter than the seals can withstand, try a hair drier. It should have a noticeable increase in drag as it gets hotter.

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post #3 of 13 (permalink) Old Jul 26th, 17, 12:08 PM Thread Starter
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Re: Can you test a fan clutch in the oven?

Dave, I could probably use a heat gun on a low setting if I wanted to concentrate the heat on the bi-metal strip. I figured on a hot summer day the underhood temps probably get to 200* easily, so I would hope that this would not be enough to hurt any seals. Maybe I should play it safe and stick with, say 175*. Thanks.

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post #4 of 13 (permalink) Old Jul 26th, 17, 12:15 PM
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Re: Can you test a fan clutch in the oven?

Tom how about a non-thermal clutch? I've run one for years... At slow rpm the fan spins 1:1 or close to it (when you need it the most) and as the rpm increases the clutch slips and almost freewheels at higher rpm... It's viscous like the thermal clutch but without the bi-metal spring etc will last longer.

Hayden - Fan Clutch Tutorial - Part 2

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post #5 of 13 (permalink) Old Jul 26th, 17, 12:33 PM
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Re: Can you test a fan clutch in the oven?

You only need to apply heat to the thermal spring and should be able to see it move visually.

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post #6 of 13 (permalink) Old Jul 26th, 17, 12:51 PM Thread Starter
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Re: Can you test a fan clutch in the oven?

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Originally Posted by Vega$69 View Post
You only need to apply heat to the thermal spring and should be able to see it move visually.
Right, but should I be able to tell any change in resistance? Logic would say that I should, but wondering if centrifugal force on the fluid would affect this.

Might just have to throw my old clutch on there and try it out. Not terribly hard to replace on this car.

Like I said, not real crazy about the generic look of most of the aftermarket ones. I like originality!

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post #7 of 13 (permalink) Old Jul 26th, 17, 03:05 PM
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Re: Can you test a fan clutch in the oven?

As said, NO. Use hair dryer or heat gun.
When fan turns on cold , it should be engaged - listen for wind noise, then unlock, goes quiet.
When heated by demand, it will lock up and sound like a school bus.
If clutch has a thermal spring, you can pull the bimetal spring out of its tab and rotate it clockwise for manually locking it up.
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post #8 of 13 (permalink) Old Jul 27th, 17, 12:47 PM
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Re: Can you test a fan clutch in the oven?

Yeah, statically testing the clutch would only let you see if the spring is moving. The clutch has to be spinning to distribute the silicone oil through the passages as its operating.

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post #9 of 13 (permalink) Old Jul 27th, 17, 04:20 PM
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Re: Can you test a fan clutch in the oven?

I would say there is no reliable "bench test".

Install it on the car to test it, that's the only way.

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post #10 of 13 (permalink) Old Jul 27th, 17, 05:55 PM
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Re: Can you test a fan clutch in the oven?

If you click in the Hayden in post #4 and go to the bottom there is a link "Next- Fan Clutch Tutorial Part 3." Very good write up on how to detect a faulty fan clutch.

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post #11 of 13 (permalink) Old Jul 27th, 17, 06:33 PM
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Re: Can you test a fan clutch in the oven?

Quote:
Originally Posted by ZZ_430 View Post
I would say there is no reliable "bench test".

Install it on the car to test it, that's the only way.
ZZ_430 is absolutely correct. When the clutch is at rest the viscous fluid drains from the central reservoir into the working plates. Rotation causes a pumping action when the thermostatic valve is open which causes the fluid to return to the reservoir. This is why the fan is engaged for a few seconds when a cold engine is first started up.

There are standard and heavy duty clutches. Heavy duty clutches should only be used with aggressive fan blades with at least 2-1/2 inches of pitch. I used a Hayden 2747 HD clutch with an 18 inch 7 blade fan from a 1979 Cadillac in my '67. This fan has just over 2-1/2 inches of pitch and when it engages it really pulls a lot of air. When I first installed it my fan belt would slip when it engaged. I tried a new belt but it still would slip and squeal. I installed different pulleys with an additional track so I could run two fan belts. That solved the problem.

My 50 year old radiator is small and not very efficient, but with this fan I never over heat even on the hottest of days idling in traffic. When the clutch engages on hot days I can hear the fan at idle and it roars when I take off from a stop.



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post #12 of 13 (permalink) Old Jul 28th, 17, 08:40 AM Thread Starter
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Re: Can you test a fan clutch in the oven?

Steve, is there any way to tell the pitch visually, or do you need to look up the part number if it is on there?

I have a 6-blade fan that fits nicely inside the shroud. I am going to throw that on there and just try it out. If I can tell that the clutch is not working properly, I will swap it with the new one I bought from NAPA.

I noticed that there is about a 1.5" gap along the bottom of the shroud and the radiator. Should I get some kind of rubber stripping and seal this up?

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post #13 of 13 (permalink) Old Jul 30th, 17, 05:52 PM
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Re: Can you test a fan clutch in the oven?

Hi Tom

I had a few issues also, bought a Fan Clutch and Fan off eBay, Went thru it, had Problems.

So is your Question for a Problem or are you trying to Eliminate a Bad Fan Clutch ?

https://www.camaros.net/forums/28-hea...roblems-2.html

Check out my Post # 20 & 22. Only time I have a little bit of trouble now is Sitting for more than like 10 minutes with the Engine running and Not moving, gets up to like 240 deg.

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