Bad clutch fan? - Chevelle Tech
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post #1 of 9 (permalink) Old Jul 6th, 13, 12:08 PM Thread Starter
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Dan
 
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Bad clutch fan?

I have just over a 100 miles on a complete restored 68 Chevelle with a 396 and a new 4-core radiator. The original stock fan shroud and clutch fan were used. It runs 190 down the Hwy all day, but in slow or stopped traffic the temp climbs to 210 degrees in 90 degree weather. I suspect my 45 year old clutch fan is the problem. So, I drove the car today and let it get to 205 degrees and shut the car off. When I grab the clutch fan, it spins fairly free (about the same resistance as it does when it is cold). I pulled the clutch fan and tested it the "red neck" way. I heated up my grill to 225 degrees and threw the clutch fan on it. It still spins with the same resistance as it does when it is cold. So, I'm assuming my clutch fan is toast and it is time to buy another one?? The local parts store has a Hayed HD 2747 in stock that I plan on replacing it with if the clutch fan is bad...........Am I on the right track?

Dan

Last edited by 68chevmn; Jul 6th, 13 at 12:51 PM.
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post #2 of 9 (permalink) Old Jul 6th, 13, 5:49 PM
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Re: Bad clutch fan?

Quote:
Originally Posted by 68chevmn View Post
I have just over a 100 miles on a complete restored 68 Chevelle with a 396 and a new 4-core radiator. The original stock fan shroud and clutch fan were used. It runs 190 down the Hwy all day, but in slow or stopped traffic the temp climbs to 210 degrees in 90 degree weather. I suspect my 45 year old clutch fan is the problem. So, I drove the car today and let it get to 205 degrees and shut the car off. When I grab the clutch fan, it spins fairly free (about the same resistance as it does when it is cold). I pulled the clutch fan and tested it the "red neck" way. I heated up my grill to 225 degrees and threw the clutch fan on it. It still spins with the same resistance as it does when it is cold. So, I'm assuming my clutch fan is toast and it is time to buy another one?? The local parts store has a Hayed HD 2747 in stock that I plan on replacing it with if the clutch fan is bad...........Am I on the right track?

Dan
================================================== =============

BTW,your local parts guy made a mistake,hayden's 2747 hd thermal fan clutch is a great unit i often use ,but its for 69 & newer sbc/bbc chevelles w- long water pump and your 68 chevelle should have a short pump that doenst use that fan clutch that if used could possibly create improper fan to rad and fan to shroud spacing issues.

You could try it to see if its same dementions as your current original fan clutch and if yes then give it a try.

But the proper hayden thermal fan clutch by application per summit for your 68 chevelle with bbc with fan clutch and or AC is Haydens 2710 thermal fan clutch,heres a link to it.

http://www.summitracing.com/parts/hd...model/chevelle

From what you say i'd say the fan clutch is toast!

Good or bad theres no way i'd trust cooling duty to a 40+ yr old original fan clutch.buy a stock rep hayden thermal fan clutch from summit or rock auto (best prices) for your yr car with bbc & optional AC.

Along with the new thermal fan clutch to reduce temp a bit more do the following:

* Along with that great working quaility hayden thermal fan clutch buy & install an autzone 15356 stat with 3/16 bypass hole drilled in it .

* Seal any airgaps between rad core and fan shroud when adheasive backed foam insualtion avail from lowes etc ,that ensures all air moved by clutch fan is actuall pulled thru the rad core for max cooling vs thru gap between rad core and shorud which reduces cooling efficnecy.

* Use 30% anti frz/70% distilled water coolant mix for better heat transfer vs std 50/50 mix .

Doing all of the above with the new fan clutch should reduce cooling temp quite a bit esp with your new hd cooling 4 row rad as long your car/motor has proper short w-pump & clutch fan along with proper fan shroud too for your 68 chevelle with bbc with optional Ac or HD cooling option so everything fits properly and works as designed.

Let us know how much doing all of the above reduces cooling temp and dont disreguard the stat i rec because its an important part of reducing your enegine overall temp so dont overlook it!.

Scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
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post #3 of 9 (permalink) Old Jul 6th, 13, 6:31 PM Thread Starter
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Dan
 
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Re: Bad clutch fan?

Scott,

I should have clarified, but I'm running a long water pump and a 1969 chevelle fan shroud, so the 2747 clutch fan I just picked up should work. The fan sits half in and half out of the shroud and I can barely get my finger between the fan tips and the shroud. There are long 1/2-inch gaps along the sides of the shroud where it pushes up against the radiator that I can tackle next if the temp is still to warm. I'm running a 185 degree thermostat with 2 small holes drilled in it, but I will leave that alone for now and see how the new clutch fan works. It is supposed to be 90 degrees tomorrow, so I will see how much of a difference it makes with the new clutch fan installed............THANKS!

Dan
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post #4 of 9 (permalink) Old Jul 6th, 13, 11:28 PM
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Re: Bad clutch fan?

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Originally Posted by 68chevmn View Post
Scott,

I should have clarified, but I'm running a long water pump and a 1969 chevelle fan shroud, so the 2747 clutch fan I just picked up should work. The fan sits half in and half out of the shroud and I can barely get my finger between the fan tips and the shroud. There are long 1/2-inch gaps along the sides of the shroud where it pushes up against the radiator that I can tackle next if the temp is still to warm. I'm running a 185 degree thermostat with 2 small holes drilled in it, but I will leave that alone for now and see how the new clutch fan works. It is supposed to be 90 degrees tomorrow, so I will see how much of a difference it makes with the new clutch fan installed............THANKS!

Dan
=====

Ok,your running a long w-pump & 69 shroud so your definately good to go with the HAYDEN HD 2747 thermal fan clutch!

And just so you know with the type cooling system setup your running installing the autozone 15356 stat w-bypass drilled will reduce overall stabilized engine temp a min of 10-12 deg over vs the 180 stat or what you say is a 185 stat your running ,$10 & 15 min work is a cheap investmemt to reduce overall cooling temp an additonal 10-12 deg.

I found this to be true from testing i did of many diff stats along with using & rec this stat for many cars/motors over the past few yrs so know 1st hand its the case.

BTW,what rad are running ,a stock type repl copper/brass 3 or 4 row rad?

Good luck & let us know what you end up doing and how it affects/reduces temp.

Scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
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post #5 of 9 (permalink) Old Jul 7th, 13, 5:33 PM Thread Starter
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Dan
 
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Re: Bad clutch fan?

New clutch fan installed and it is pushing 10 times the airflow as the old clutch fan. Cruising temperatures are down about 3 degrees, but idling or stopped in traffic temp's only climbed about 5 degrees from the highway temps............so the temp gauge never went above 195 with the outside air temps in the low 90's. I'll probably install the thermostat you recommended this week! Thanks for the help
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post #6 of 9 (permalink) Old Jul 7th, 13, 8:49 PM
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Re: Bad clutch fan?

Quote:
Originally Posted by 68chevmn View Post
New clutch fan installed and it is pushing 10 times the airflow as the old clutch fan. Cruising temperatures are down about 3 degrees, but idling or stopped in traffic temp's only climbed about 5 degrees from the highway temps............so the temp gauge never went above 195 with the outside air temps in the low 90's. I'll probably install the thermostat you recommended this week! Thanks for the help
=====================


Thats great!

Your just fine with a max of 195deg in mid 90's outside airtemp esp with a bbc.

BTW,you said it was going to as high as 210 deg in 90 deg outside temps with the prior /old fan clutch so installing the new Hayden 2747 HD thermal fan clutch reduced temp a full 15 deg at times going from 210 deg with old fan clutch down to max of 195 deg in same 90 deg heat with the new HD thermal fan clutch.

But with your setup i'd be very surprised if the 15356/160 autozone hi stat i rec doesnt reduce overall stabilized op temp an additonal 10 deg or more like it has in other similar setups i have used it in just like yours.

Dont forget to drill a 3/16 air bypass hole in the stat housing and to also seal airgap between shroud and rad core to ensure all air moved by clutch fan is actually sucked thru rad core for max cooling efficniency.

Lastly,ensure your running plenty of base timing if motors got an aftermarket perf cam of approx 18 deg base/36-38 total.

Thats because retarded base timing increases engine /exhaust temp esp when at idle in traffic so dont overlook that either.

Vac adv hooked to full int can also help reduce engine temp too as long as its limited to 10-12 deg max using cranes vac adv limiter plate .

Why do i say that,well that because the stock vac adv can give as much as 20-25deg when fully activated which is too much along the additonal 10-12 deg base timing the aftermatrket cam requires over a milder stock cam with less duration/overlap requiring pnly 4-6-8 deg BTDC timing on avg depending on motor and trans.

Let us know how much the temp is futher redeuced installing the autozoner stat ,sealing all airgaps between shroud to rad core along with maybe adv base timing a bit if its not where it need to be too

OH,off topic but if thats the original fan clutch to your car you just removed i have contact info for someone that rebuilds/restores fan clutches.

PM if your intrested in that info and i will try to locate it for you.

Scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
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post #7 of 9 (permalink) Old Jul 8th, 13, 6:26 PM
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Re: Bad clutch fan?

What's the problem... 50/50 mix is good to 240...

70-454 LS5

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post #8 of 9 (permalink) Old Jul 8th, 13, 8:58 PM
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Re: Bad clutch fan?

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Originally Posted by 71-454 View Post
What's the problem... 50/50 mix is good to 240...
=============

Its not about 240 boil over protection at all.

The additonal water in the 30/70 not increases the coolants ability transfer heat while still providing decent corrosion protection and protection in colder temps to maybe 10-20deg F where as the 50/50 coolant mix is good for at least 0 deg f or more.

But i would have to mix & test those 2 coolant ratio mixes again to be 100% sure of the coldest temps they are good for.

The tride & true 50/50 mix is just fine for mosts setups but when cooling is an issue the 50/50 mix doesnt have quite as good ability to transfer heat as the 30/70 mix does.

So when your looking to reduce engine temps everything you can do collectively together to help reduce temps needs to be done which is why i often rec it.

Scott

SCOTT
1969 CHEVELLE SS396,ORIGINAL #'S MATCH,GOT IN 1978,(In 2001 rblt/bored original 396 .030 to 402)/M20/12BOLT/3:31'S
2002 MAXIMA (DAILY DRIVER/1 owner,GOT 3/2013 w-44k miles)
2009 HD ELECTRAGLIDE CLASSIC ULTRA (GOT 11/14 W-9,700 miles)
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post #9 of 9 (permalink) Old Jul 8th, 13, 9:30 PM
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Re: Bad clutch fan?

Guessing 71-454's account may have been hi-jacked as he posted the exact same thing in 3 different threads, where no one was even talking about it.............

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