Finally solved my over heating problem!!!

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nm9stheham said:
Hmmmm.... who woulda thunk that 2, count 'em 2, electric fans would not be enough? LOL

Glad you got it fixed and thanks for posting the solution for the benefit of others.
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Because all electric fans are equal to one another.
 
the electric fans are not being use as designed there for failure , they were designed to work on ac condensers with 2 or more mounted inside a full radiator shroud /some sales person got a bright idea on how to make money off people. 2 12 " fans will drop the condenser 200degs in 20 seconds these fans have been used for 40 years on over the road transportation /refrigeration. making full fan shrouds takes space and are ugly and make it hard to sell , just look at a jeep with the 4.0 with both fans made into the same shroud very efficient for a 12 " tall crossflow radiator .
 
To the OP: Just keep an eye long term on those stainless steel fan blades; I have used 2 of them over the years and both had blades crack on them after a couple of years on the street. They tend to crack close to where the blades meet the center spokes.

To follow up on redness's and teringer's posts: The thing about the electric fans that is not obvious is that with the thin style fan blades, even a small amount of pressure drop into the fan inlet or pressure build-up at the fan outlet will make the through-flow drop like a rock. What happens is that with even a small pressure difference inlet-to-outlet will cause the air being pushed outward by the blade to simply flow around the blade and back to the front side of the blade. So it ends up moving the same air molecules around and around itself, instead of moving a continuous flow of air through the fan. The thinner the blades, the more this problem crops up. So a fatter blade will do much better with any pressure drop across the fan and shroud, like the blades you see on factory electric fans and stock factory metal fans.

If you look at any catalog for any fan like pictured by the OP, you can find flow numbers in the 1500-2000-3000 cfm range, but those numbers are only for a perfectly free flowing situation. As soon as you put these behind a radiator and a tight shroud, you are going to get a low pressure area behind the rad, and this circular flow around the blades will occur, and the total through-flow will drop into the toilet. This is what happens with inexpensive electric fans in a tight shroud at idle or low speed.
 
nm9stheham said:
To the OP: Just keep an eye long term on those stainless steel fan blades; I have used 2 of them over the year and both had blades crack on them after a couple of years on the street. They tend to crack close to where the blades meet the center spokes.
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I have seen these fans make holes in hoods, even with shrouds.
 
I guess electric fans have their place, but one of the main reasons people use them is to reduce noise. However, it's difficult, if not impossible, to move a large quantity of air without noise. That's why you hear garbage trucks, semi's, buses etc with extremely loud engine fans...they do the job.

I stand by my assertion that a good thermostatic fan is the best there is. If you average the amount of engaged time vs. disengaged time, you probably hear LESS noise with the thermostatic fan than you would with the electric fan running.

I too have heard of those stainless fans self-destructing, and the shrapnel does a lot of damage to anything it hits. I have a thermostatic fan from a slant six that may be a type that is thin enough to fit in there. I think it is less than 3" from the hub mounting surface to the area closest to the rad.
 
Hey Tyler....I will keep an eye on the blades for cracks. The fan has 15,000 miles
on it now. I was running it with the old radiator and fan shroud. If it should start
to fail I will look for a solid steel fan.

Thanks all,
Tony



TylerW said:
I guess electric fans have their place, but one of the main reasons people use them is to reduce noise. However, it's difficult, if not impossible, to move a large quantity of air without noise. That's why you hear garbage trucks, semi's, buses etc with extremely loud engine fans...they do the job.

I stand by my assertion that a good thermostatic fan is the best there is. If you average the amount of engaged time vs. disengaged time, you probably hear LESS noise with the thermostatic fan than you would with the electric fan running.

I too have heard of those stainless fans self-destructing, and the shrapnel does a lot of damage to anything it hits. I have a thermostatic fan from a slant six that may be a type that is thin enough to fit in there. I think it is less than 3" from the hub mounting surface to the area closest to the rad.
Click to expand...
 
TylerW said:
I guess electric fans have their place, but one of the main reasons people use them is to reduce noise. However, it's difficult, if not impossible, to move a large quantity of air without noise. That's why you hear garbage trucks, semi's, buses etc with extremely loud engine fans...they do the job.
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Roger that. I have to occasionally select cooling fans for electronics enclosures, and if it is going in a quiet location, one simply has to go to a very low fan speed, and use a larger enclosure, and use internal stirring fans. And we use boxer type fans with stout blades and a thick fan body to keep the blades efficient, not these thin bladed things from the auto catalogs.
 
Nice job Tony! I just had the exact same problem as you and I spent a ton of time and money and finally decided to put my old mechanical fan back on and it cools wonderfully now. Electric fans aren't all their hyped up to be!
 
Personally I think (I have no first hand experience) if you wanna run electric fans use one from a factory produced car, not these aftermarket ones. I parted a 92 3.1 Firebird a few years back and kept the electric fan to use on a future project (I'll probably put it on my 72 Duster) I hooked it up to a battery on the work bench and that sucker blew dirt, papers, packing peanuts, etc clean of my work bench!! That thing will move some SERIOUS air!! But I'll know how it works on the car in a few months to a year.
 
I did end up putting my old shroud back on. Had to cut the bottom out of
it so it would slip down over the fan, no room to install it otherwise. Very, very
happy with the in town driving now.
 

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Guessing this is my issue with my 71 demon been fighting a cooling issue ever since trading for it. Being new to these muscle cars I'm learning. It also has what looks to be insanely cheap electric fans, no shroud as well and barely pumps air. Will be putting stock parts back on next summer
 
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