Clutch Fan Problems?

[STREETRODS]

My 79 Vette W A/c Is Running Hotter Than I Feel Comfortable With. The Temp Stays About 220 Give Or Take 5 Degrees A/c Or Not.
I Have A Clutch Fan-i Have Never Ben A Fan Of Clutch Fans- Could That Be The Problem, Or Is That The Normal Operating Temp? The Gage Red Lines About 240 But That Seems Awfully Hot. Were Leaving On A 10 Day Trip, And Would Hate To Spend Part Of Our Vacation In A Garage That's Not Mine!
Dave

 

[78SilvAnniv]

Hi Dave,
I'm gonna sound like a broken record around here (CAC), but I am a big fan of the flex fan. We suffered through 11 years of summer run-hot conditions before the flex fan fixed everything.

It has been stated in other threads, that the GM cooling system works, when all components are in operating order...but we had replaced many things trying to get our summer run-hot condition to go away.

We had replaced the clutch fan yearly, and sometimes twice a year.
Radiator flush, water pump, belts/hoses, t-stat, kitchen sink...
New Radiator and crate engine and we still had the same problem.
Anything above 60mph during the summer made the temp run at 220. Use the AC?...temp would shoot to 240!
(our air dam/valance was in good working order)

Anyhow, we moved across the country and when summer rolled around I was frustrated at my high temps and bought a flex fan. I have yet to go over 200* at any sustained speeds or during spirited (high revs @ low speeds and faster sustained speeds) mtn driving while keeping up with newer vettes.

Do be sure your engine is tuned and all parts are in working order to be certain there is not another cause, but for me...the flex fan cured it.
Heidi

 

[photovette]

I am not a fan of flex fans--I put one on last summer and after 2 months the fan blades disintagrated, throwing blades through the shroud, hoses and belts--luckily none went straight up through the hood. Also, lucky I wasn't nosing around under the hood when it blew too.


I will say Hayden made more than good on the damage once they determined it was a factory defect--plus they gave me a new HD fan clutch!

 

[Jack]

My 79 Vette W A/c Is Running Hotter Than I Feel Comfortable With. The Temp Stays About 220 Give Or Take 5 Degrees A/c Or Not. I Have A Clutch Fan-i Have Never Ben A Fan Of Clutch Fans- Could That Be The Problem, Or Is That The Normal Operating Temp? The Gage Red Lines About 240 But That Seems Awfully Hot. Were Leaving On A 10 Day Trip, And Would Hate To Spend Part Of Our Vacation In A Garage That's Not Mine!
Dave

Idaho vette ... probably sits up a fair amount. I'd suggest a real good radiator cleaning inside & out ... not just a flush but a real cleanout. Best stuff out there is at GM parts dept ... GM P/N 12346500 it's actually Prestone P/N AS100 Heavy Duty Cooling System Cleaner ... but you'll rarely find it anywhere but dealer ... under $10 ... strong stuff, not what you'll find at WallyWorld or Advance ... wear eye protection. Get a free DexCool plugged radiator service bulletin (#99-06-02-012D) printout at GM Svc Dept dealer ... it'll walk you through a cleaning procedure that REALLY works ... just don't refill with Dexcool ... use green stuff. Also, compare and verify your gage with a known gage.
JACK:gap

 

[rob77]

Hi there,

I have a recently rebuilt 77 engine which was running hot from day one. Everytime I tried installing the thermostat (180 or 160) the temp would sky-rocket, so I finally just removed it altogether. Even without the thermostat I was running hot at sustained high speed driving (up to about 240 on the guage). I though that the fan clutch was defective so I replaced it. This still didn't fix the problem. I just replaced the stock fan and clutch with a 10,000RPM flex fan and to my suprise the temp hasn't gotten over 200 yet. I'm sold on the flex fan.

Rob

 

[magoo]

I had the same story as Heidi with my 62, and a flex fan fixed everything. I certainly vote for the flex fan. At least as a quick fix for your trip or until you feel like taking on the problem with things like a new bigger radiator, and whatever other components you may need to put the clutch back on. I even like to hear it whirrrrr, so I'm leavin it on my 62. Good luck.

Mike

 

[rob77]

I don't even hear a difference in sound with the flex fan. Maybe my hearing is going!!
Rob

 

[78SilvAnniv]

It's gotta be your hearing, Rob! :L
The flex fan pushes so much air under my car, at first I thought it sounded like I had a crop-duster under there! It did take a while for me to adjust to the roar of the massive amounts of air being forced through there, but I did adjust. I LIKE knowing that much air is getting moved around.
Heidi

 

[75 flame orange]

it worked for me!

i had the same problem with high temps in my motor.flushed cooling system,put in a high flow water pump,180* stat,new hoses and saw a post from hedie about the flex-fan.i pm,d her and got the info on 2in spacers and size of fan she used on her car.went to the parts store got what i needed,that cured my problem.now the temp doesn't get over 200* on the hottest days.hedie's post worked for me(thank's again hedie)
carmen

 

[Bob Chadwick]

You need to give more information to completely diagnose the problem. Does it get hot in traffic or at speed?

Is your front valance in place? Are all the radiator seals in place. If yes to both of these, I would have the temp checked with one of those spot guns to make sure it is not a gauge/sending unit issue. If it was, it wouldn't be the first Vette that was not running the temp reported by the gauge. Any shop will have one or they can be bought at NAPA for under $100.

Better to know where you sit before you start throwing money at it.

I did a search using temperature and JohnZ, one of the CAC guru's on the subject, in the C3 forums and came up with these posts. Take a look through them and I think you will get a good idea of the issues.

I run a completely stock cooling system on my 77 and get 200 degrees on the freeway on a hot day with the a/c on and can get as high as 220 in stop and go traffic with the a/c on. That's assuming the gauge is accurate.

 

[L48]

I do not disagree with most of these suggestions. However I want to add a vote for the radiator. There comes a time when no amount of flushing can fix that old radiator. It may not be leaking but it may not be cooling efficiently either.

More than once I have been burned by this. The first time was on an early 80's Olds 88. It kept overheating. It had 200+ thousand miles. I changed the water pump. Kept overheating. Then one day it overheated real bad. Thought I blew a head gasket. Found another motor and put it in (long story but I had the old engine out and went to move my new water pump to the replacment engine and found the impeller had fallen off the shaft inside the pump). Still overheating. Put a metal strap in to bypass the clutch in the clutching fan. Still overheating. Changed the radiator. Overheating stopped.

To a lesser degree I had cooling problems with my 78 LeMans (327 Chevy engine). It had a 3 core but it wasn't enough. Bought a new Modine and the problems stopped.

Over time the fins lose their contact with the cores and the cores get clogged up.

I know it is more expensive but if it does the job right then it is worth it. I would say if you changed the clutch and there is no change in the temperature then the problem is probably not the clutch.

Also, the fan should not be to far in or out of the shroud. I am not sure how this could happen but I know the fan does not work as well if it does not line up with the shroud right.

I personally do not like the sound of that flex fan, and plan to remove the one that came on mine as soon as I can find a replacement and time to put it on - probably a clutching fan or maybe electric fans.

 

[craig32]

ok, I've been out of the loop for awhile - why aren't solid 4 blade metal fans used anymore? Just wondering.
Craig

 

[Bob Chadwick]

When working properly, the clutch fan disengages when not needed increasing power.