MotorHead

Driving around the motor stays 170 -180 degs but as soon as I stop in traffic it starts to climb like ten degees in a minute or so. I am sure it would overheat in a matter of minutes, it was the same way with L48 in it so it is not the motor.

I am thinking the clutch fan might not be operating properly but so not know how to check it.

Older Than Dirt

I have electric fans but I do remember reading somewhere that when you shut off your engine the fan should only make a couple of revolutions. If it spins more than that before stopping then the clutch is bad, but then again what I read could be false propaganda.

TLChydraulics

A good clutch fan shouldn't free-wheel much at all. I don't know if there is a special way to test them, but see how it free-wheels. When I spin mine by hand, it goes around about 1/2 to 3/4 rev after my fingers release it. I have a much older extra one that goes around twice, probably not good.

Good luck!!!



Loren

SanDiegoPaul

First off, it's a 'Fan Clutch' not vise-versa.

Now to check operation, all you need to do is see how much air it throws back with the engine at a hot idle.

When cold, at a fast choke idle, the fan clutch should engage the fan just enough for airflow to be easily felt behind the fan.

HowEver! Once you reach operating temp, the clutch on the fan should sense the radiator heat and stiffen up enough to cause a great wind tunnel behind the fan.

:flag

rob75383

I just got back from driving her around for about 1.5 hrs.
I just did the hand-spin test, and after I release the fan, it only rotates enough to bring the next blade to the starting position...
So mine only goes about an 1/8 of a rotation, or about 45 degrees.
My engine is still hot, though.
I should check it when I wake up, to see if there is a differance.

Love My 72 and 77

I say better to be safe than sorry go spend 50 or so bucks on a good new one - replace thermostat and drive the wheels off

gkvetteuno

Just curious if this is uncommon. A 10 degree rise while in slow or stopped traffic was not uncommon on my 71 Vette with A/C, especially if it stabilizes at the 180 to 190 range. If it continues to rise thats a problem.

gliot1

I think you might be wasting money. Vettes get hot in traffic. Don't keep the air c on if you have it. I once stopped on the side of the road with the air on. When I came back to my car the temp was 235 in about 5 minutes. These cars all run hot. The electric fan is the best solution, but obviously not orignal.

Disco_Mike

from the Haynes manual (slightly edited)
1. start with luke warm engine (start when cold and run for 2 minutes only.)
2.turn the fan blades and note the resistance. There should be moderate resistance depending on temperature.
3.drive vehicle until the engine is at operating temperature.
4. turn the fan bladesand again note the resistance. There should be a noticeable increase in resistance.
5.replace fan clutch if fails this tests or is locked up.
6.also look for excessive fluid leaking from the hub or more that a 1/4 inch of lateral play is noted.

MotorHead

quote:" First off, it's a 'Fan Clutch' not vise-versa."

Hmmm, you must have assumed I was talking about the clutch part of the clutch fan when in reality I was talking about the whole unit, clutch and fan not working hence the term clutch fan was used not fan clutch. How much wood could a woodchuck chuck.....


I don't think mine is working properly could not notice any difference in resistance at 130deg and 190deg. I am going to get the Flex-a-Lite 210 kit.





[Modified by MotorHead, 6:35 PM 7/6/2004]

Jim Martley2

One thing to make sure of is that the radiator is "sealed" to the support and the shroud is sealed to the radiator. You want to make sure that the fan is pulling air ONLY thru the radiator core, not around it.

Rockn-Roll

If you are just sitting there, and the fan is working properly, which it appears it does. Then, you need to make sure the fins are all clean, that the radiator is completely sealed around the shroud, and that coolant is flowing at the maximum possible speed...which means checking the thermostat. Personally, I remove the thermostat from any car I drive...even in Washington State where it's colder. But, if you have a thermostat that is more than a year old then it may just need to be replaced with the stock temperature rating....I believe the base models required 180º while performance models got a 190º. But, the carburated base models could go with a 160º if they felt like it as that is the temperature that the engine will normally run at if it had no thermostat.

darrentpi

My 69 has a big block, and it is the same, runs fine when driving, but in traffic, shoots up to above 200, makes you wounder if this was how then ran back in the day when they were new. I find runing with the headlights up helps a little.
DM.

madmike

I got rid of my mechanical fan and put 1 16inch fan and 1 10 inch fan side by side. Both electric fans. They fit perfectly. It is also easyer to remove and attach the radiator and all front pulley belts. Much more room. You can also buy a aftermarket fan with 7 blades with no clutch. If you are still using the shroud, make sure it is properly sealed. There is no room for a push electric fan though that would be ideal. rats...

Taijutsu

Like many forum members I fought the temp wars. I have upgraded to dual spals, no more problem. Before I went that route I founf a summer solution. I eliminated the clutch w/machined spacer. I had 100% cooling. I still have the 7 blade fan and spacer. First $50 + shipping takes it all!

Rick