cooling fan

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72CS

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Hi all,

Quick question; I have a black rad fan that spins freely when engine is off and cold. I noticed that when starting up the engine (fast idle) the fan appears to fully engaged (masive amount of air flow at 2000rpm). Is this normal? Ideas?

Thanks,

Fabio
 
fan

When you turn the car off does the fan continue spinning freely? If it does some or a lot, you may want to replace the fan clutch.
 
To spin or not to spin?

Your fan has a thermostatic clutch. When cold, the fan spins freely as an aid to engine warming. Once warm/ hot the fan should engage and the amount of air should be appreciable. The second benefit is that when the car is moving and enough air is cooling the engine, the fan can free wheel and save a little hp and cut down on noise.

Your description sounds normal if you haven't noticed any temperature changes on the guage. A malfunction would be free wheeling or locked all the time.

Tip- the single newspaper test- when cold and engine running you can stick a single rolled up piece of newspaper in the fan and it should stop.

Note- early cars used a friction fan clutch and looks quite different than the multifinned thermo clutch. This test doesn't work on those if that's what you have and haven't converted to the new fan/ clutch/ pump. Yes, they're still out there after all these years.
 
61Porsche, I am one of those who appear to have the early clutch, it looks like a hockey puck with no fins as you mentioned. Do these freewheel when cold too? Mine is full on no matter the temp or rpm, how should these work? I have a spare replacement but havent installed yet.
 
Early fan

No not really.

If the fan appears to be running true ( not wobbling excessively) there's nothing really wrong with it. When I do work on the radiator, flushing etc. I take mine apart to check the bearing/ bush. I take it that the bush is bimetallic of sorts and expands.

The real problem with the early is free wheeling at speed. The second - the pump; if yours goes out the new ones only accept the new type of clutch.

Since I haven't had a problem with overheating other than t-stats, I leave it. For those that have a problem or might, a temporary solution to the original fan free spinning is to lock it up using two longer bolts.
 
Radiator or cooling fan--

You state the fan is black--how many blades does it have? 9?
My guess is that you have an upgraded newer type fan that is coupled to a viscous finned fan clutch.

All original fans were--to the best of my knowledge--orange and had 5 blades--the fan clutch was a friction clutch that was activated with an early bi-metal clutching arrangement--and when worn out--many simply bolted it in a "fixed" running condition--that is--always on.

I wonder why we haven't required that to be a registered person on the message board you have to indicate your geographical location country, state, town--it would remove the guess work as to where you are and help in other ways--without "blowing ones cover"
 
Thanks for the input and suggestions on what to look for. The fan is definitely clutched and is the 9 blade black repalcement type. What suprised me in it's operation was that it appeared to be fully engaged even when the engine was cold (right after start). I will go back and try a couple of the things to try understand what is going on.

Cheers.
 
hi
someone told me long ago, that a simple check of the fanclutch was that when the engine is warm enough so the radiator is fully working(BOTH UP AND LOW HOSES ARE WARM) you should stop the engine and the fan should stop immediately or maximum make two turns
it is a simple check
but for me the key is that if you dont have any malfunction, or gauge to the red area, just forget about it
regards
 
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