Moparts

How do I test my clutch fan?

Posted By: JeffRacerG

How do I test my clutch fan? - 06/14/11 01:31 AM

Car got a little hot while idling in last week's heat and I figured one of the first hings to check would be the clutch on the fan. Sould it lock when idling, or lock when the engine gets hot. Not sure whether it works by heat or rpms. It is a 1970 Road Runner.

Attached picture 6681482-CarShow2017.jpg
Posted By: mopar346

Re: How do I test my clutch fan? - 06/14/11 02:46 AM

I don't believe it ever actually locks up. Get it hot and running at idle then cut it off the fan should stop with in a few seconds or a few rounds. With the engine off but hot, spin the fan be hand, it should have a reasonably amount of resistance and it should only spin about 1-1.5 rounds when you spin it with some force. With the car off grab the fan and check the bearing for slack. If it fails any of these I would replace it.
Posted By: ahy

Re: How do I test my clutch fan? - 06/14/11 03:48 AM

Quote:

I don't believe it ever actually locks up. Get it hot and running at idle then cut it off the fan should stop with in a few seconds or a few rounds. With the engine off but hot, spin the fan be hand, it should have a reasonably amount of resistance and it should only spin about 1-1.5 rounds when you spin it with some force. With the car off grab the fan and check the bearing for slack. If it fails any of these I would replace it.





A 1970 would likley have a "thermal" fan clutch. It has a little coil in front that senses temperature and tends to engage or "lock up" meaning it slips less when hot. If it fails the tests above, replacement is needed. My one experience with parts store clutches on a DD - torqflow brand - was not good and I went with OE. The MP re-pop setup from Mancini works well on my 1970E. The kit I used comes with a 5 blade "low drag" fan which worked fine in my application, however, with cooling problems I would go with the OE fan which is usually bigger/more aggressive or an even bigger fan like the 7 blade used on mid/late 70's BB Chrysler's (JY) or the 6 blade fan from Bouchillon.
Posted By: WyleECoyote

Re: How do I test my clutch fan? - 06/14/11 05:00 AM

While the engine is off, grab a fan blade at the 12:00 position and hold it firmly. Have someone start the engine (while you are still holding the fan blade and keeping it from turning) and take the engine to 2,000 rpm's and hold it steady. Let go of the fan blade and the fan and clutch should catch up to the 2,000 rpm's within a few seconds. If it does not - then it's not working correctly.
Posted By: A12

Re: How do I test my clutch fan? - 06/14/11 05:32 AM

Quote:

While the engine is off, grab a fan blade at the 12:00 position and hold it firmly. Have someone start the engine (while you are still holding the fan blade and keeping it from turning) and take the engine to 2,000 rpm's and hold it steady. Let go of the fan blade and the fan and clutch should catch up to the 2,000 rpm's within a few seconds. If it does not - then it's not working correctly.



........oops forgot I don't have a clutch fan
Posted By: Commando1

Re: How do I test my clutch fan? - 06/14/11 01:07 PM

Quote:

While the engine is off, grab a fan blade at the 12:00 position and hold it firmly. Have someone start the engine... and take the engine to 2,000 rpm's...


Ummm. You hold it and I'll start it....
Posted By: scratchnfotraction

Re: How do I test my clutch fan? - 06/14/11 02:57 PM

Quote:

While the engine is off, grab a fan blade at the 12:00 position and hold it firmly. Have someone start the engine (while you are still holding the fan blade and keeping it from turning) and take the engine to 2,000 rpm's and hold it steady. Let go of the fan blade and the fan and clutch should catch up to the 2,000 rpm's within a few seconds. If it does not - then it's not working correctly.



wyleE is this the ACME clutch fan tester!!

hold fan while car flips over a few times
Posted By: John_Kunkel

Re: How do I test my clutch fan? - 06/14/11 09:39 PM


When it comes to fan clutches the factory says the only way to test a unit is to replace it with a known good unit.....I totally agree.
Posted By: willard

Re: How do I test my clutch fan? - 06/14/11 10:01 PM

Quote:

While the engine is off, grab a fan blade at the 12:00 position and hold it firmly. Have someone start the engine.




If I did that with my fan, I'd probably lose a few fingers. My fan clutch seized and acted like a solid spacer.
Posted By: mcmopars

Re: How do I test my clutch fan? - 06/14/11 10:36 PM

Quote:

Quote:

While the engine is off, grab a fan blade at the 12:00 position and hold it firmly. Have someone start the engine.




If I did that with my fan, I'd probably lose a few fingers. My fan clutch seized and acted like a solid spacer.




i tried that with my lawn mower,once,once
Posted By: 392charger

Re: How do I test my clutch fan? - 06/14/11 11:20 PM

I got bit by my lawn shark (lawn mower). Now got two less toes to show for it. Makes counting to 20 a real challenge . My friends call me Kunte Kinte !
Posted By: Challenger 1

Re: How do I test my clutch fan? - 06/14/11 11:26 PM

I can hear mine working, like when I get off the hi-way and come to a stop. Then when I take off I can hear the sound of my fan, it's louder. Then as it cools off the fan get's quiet again.

I have had 2 car's over the years that overheated at slow speeds or idle, both times new fan clutches fixed my problem and I could hear the fan again when it was hot. I have a 7 blade stock fans.
Posted By: WyleECoyote

Re: How do I test my clutch fan? - 06/15/11 02:49 AM

Quote:

Quote:

While the engine is off, grab a fan blade at the 12:00 position and hold it firmly. Have someone start the engine.




If I did that with my fan, I'd probably lose a few fingers. My fan clutch seized and acted like a solid spacer.



Okay - STEP 1 - Make sure clutch fan isn't seized and is free turning (see schematic).....

Posted By: A12

Re: How do I test my clutch fan? - 06/15/11 03:23 PM

Well Ron with your screen name's history can you really blame us for questioning that procedure you posted with that one small forgotten detail.. but Wiley always does that too


Can I hold it with something else besides my hand/fingers; like maybe a broom stick for now?


MikeR
Posted By: MLR426

Re: How do I test my clutch fan? - 06/15/11 04:10 PM

Quote:

Quote:

While the engine is off, grab a fan blade at the 12:00 position and hold it firmly. Have someone start the engine... and take the engine to 2,000 rpm's...


Ummm. You hold it and I'll start it....



no you hold it and I'll start it

logan426
Posted By: HitIt

Re: How do I test my clutch fan? - 06/15/11 04:56 PM

That's nothing. You should see how he tests a high speed vibration.
Posted By: scratchnfotraction

Re: How do I test my clutch fan? - 06/15/11 07:48 PM

ACME is the #1 mail order company

you mean they have a high speed vibration tester too?

Posted By: 360view

Re: How do I test my clutch fan? - 06/17/11 02:23 PM

back to the OP
consider using an electric heat gun
and for the other lower temperature extreme
'Quick Freeze' spray cans
to make the bi-metallic coil
lock or unlock

compressed air expanding through a
'blow gun nozzle' will also be cooler than normal outside air

with these two ways of heating or cooling the fan clutch,
and a non-contact infrared temperature meter
I would guess you could find the lock and unlock temperatures

On a 1995 360 Magnum V8 the Dodge Field Service manual says the lock temperature is approximately 220 degrees F,
which is also where the nominal 195 degree factory Stant 'Regular Grade' thermostat with steel body and brass underarms is supposed to be fully open. 195 degrees is where that factory thermostat is supposed to just start opening.
Posted By: JeffRacerG

Re: How do I test my clutch fan? - 06/18/11 01:53 PM

The parts book (computer) at work shows both thermal and non-thermal. Is either one better than the other and which one should I get?
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