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Rob J

How to tell if a fan clutch is good or not?

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So, as I media blast, and recondition parts, i get to the fan clutch. Visually it appears in good shape, and wasn't too corroded or dirty. After media blasting, it looks brand new. But, how can you tell if mechanically it is functioning properly. If I don't have to replace it, I'd like not to, but if I should, $69.00 will take care of it. Should I try and salvage it, or not bother?

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When you hold the flange and spin it, does it freewheel or is there some resistance. If it freewheels, that's the first clue it's bad. After that, I don't know if there is a test that can be performed. Have you googled it? There is a lot of info.

Edited by mt65riv (see edit history)

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Yes, there is sufficient resistance, which leads me to believe it is ok. It's an easy part to change later down the road after the restoration is complete if needed, so I'm just going to refinish it with some Eastwood Alumi-blast and call it ok.

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Is it the thermostatic clutch type? Those are identified by the bi-metal coil in the front, at least on the GMs. Testing that type is different than just spinning it to feel the drag.

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I personally would let the car warm up then see what kind of drag is on the clutch. The cheat we always did was turn the car off and see how long the fan spins. More than a few turns and we yanked it. I lived near death valley many years ago and changed out my share of clutches on the Big block Chevy. There's not room for cooling system flaws when it's 115 degrees. A 4 core radiator was mandatory.

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It'll be kind of hard to warm the engine up now. Doing a nut and bolt frame off, and the car is apart.:eek:

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Rob-

If you do not personally know how old the clutch is, I would recommend replacing it. Be sure to put one in with the coil spring in the front. I did not remember it costing $69, but I bought mine a few years ago. You can get it form your local auto parts store. You do not need to pay high prices from a specialty parts vendor. Tell them you need an Imperial part # 215049. If they try to substitute the cheaper version without the coil in the front, tell them no, you want the other model. My local Auto Zone had this fan clutch in stock when I bought it, it was not even a special order.

For anyone who has a fan clutch on their car and the engine is running, my check of the fan clutch is as follows:

1. Drive car for at least 20 minutes to get engine and radiator up to normal operating temperature.

2. With hood up, transmission in Park or Neutral, run engine RPM up to about 2000. The fan should "roar". If it does not roar, the clutch is bad.

When I am driving down the road on a hot summer day, I can hear my fan clutch go on and off because I can hear the fan noise go up and down.

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Rob-

If you do not personally know how old the clutch is, I would recommend replacing it. Be sure to put one in with the coil spring in the front. I did not remember it costing $69, but I bought mine a few years ago. You can get it form your local auto parts store. You do not need to pay high prices from a specialty parts vendor. Tell them you need an Imperial part # 215049. If they try to substitute the cheaper version without the coil in the front, tell them no, you want the other model. My local Auto Zone had this fan clutch in stock when I bought it, it was not even a special order.

For anyone who has a fan clutch on their car and the engine is running, my check of the fan clutch is as follows:

1. Drive car for at least 20 minutes to get engine and radiator up to normal operating temperature.

2. With hood up, transmission in Park or Neutral, run engine RPM up to about 2000. The fan should "roar". If it does not roar, the clutch is bad.

When I am driving down the road on a hot summer day, I can hear my fan clutch go on and off because I can hear the fan noise go up and down.

Jim, is this part the correct one for a 425 DQ motor with AC?

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The easiest way I have ever checked a thermostatic clutch fan is hold the fan then have someone start the car. The fan will not start to turn until you release it from your hand then it will come up to speed. If it does not come up to speed quickly then it is wearing out. I understand you all will say never put your hands in the fan but I have checked them this way and never lost my hands. Always use caution around a fan but if you do as I said it should work.

Thanks,

John A Wettengel

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If you do decide to put your hand down there, you'd better make sure that the clutch fan is not stuck in the on position or the thermostat in it is warm enough to engage it. I'd be more inclined to listen from a distance than to take a chance on the fan being bad and spinning with the engine. You can also visually match the speed of the fan to the speed of the pulley. If it's not as fast when it's cold, it's not engaging. If it never matches speeds with the pulley, it's bad. Scary stuff there dude!

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^^^^ Agreed! NO HANDS ON A RUNNING ENGINE'S FAN!!!! ^^^^

Sounds like it could be one of those "Hey ya'all, watch this!" moments. :D

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I think that should read "Have someone hold the fan and then YOU start the engine"

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We'll know it failed when he can no longer post on these threads. :eek: (no fingers - no typing)

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This is one of the most read threads in the forum.  It seems the only way to know if the clutch works is with the car back together and running.  Is there no bench check you can do?

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                 The only way to bench test a thermostatic fan clutch is to take a torch   and heat up

the coil on the front of the fan clutch till it's 220 degrees, then grab the blades of the fan while holding the clutch hub with your other hand and see if it has good drag with no free wheeling. It should turn a revolution or less and stop when you try to spin it. You can use a laser temp gun to determine if you have heated up the coil sufficiently for the test.

Edited by Seafoam65 (see edit history)

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