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I did something I always wanted to do: drove the baby in a parade. During the parade, which was about a half hour drive at idle speed, I noticed she was starting to roll hot. She died on me in mid parade (embarrassing) but did restart and finished the parade, with me shifting in to neutral every so often and revving the heck out of the engine (Kids loved it: "PEEL THE TIRES! PEEL THE TIRES!" No, you goofballs. I'm trying to keep the car going... Still...)

When done, I dropped off our town's mayor (he was a good sport about the overheat. said it happens to a lot of guys...) and took her for a ripping ride through the back country roads outside of town. Temp dropped back to a normal range and was fine after that.

She's a 1968 coupe, 289, 2V. Carb was recently rebuilt, engine was recently rebuilt, radiator is brand new as are the hoses, thermostat etc. She's got a four-blade water pump fan with a shroud. When I bought her, she had overheating problems, which I fixed with the shroud. The radiator swap was due anyway and has kept her cool without incident. Obviously, idling through a giant parade is the problem, but I know classics do manage to make it through these things.

My question: How do you do it? Any tips would be appreciated, as the mayor liked the ride and wondered if I'd be up for it again.

Thanks and have a great fourth!

Doc
 

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there's a product called watter wetter coulant additive it will drop you down 10 degrees but the true fix is a electric fan latemodel restoration has a kit thats called Black Magic Extreme flows 3300 cfm compared to most that flow 980cfm lots of air movin comes with everything nice setup you can always put the stock parts back on if need be but its not worth blowin a head gasket to stay stock
 

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I have used the heater to help dissipate some of the heat. It does get hot inside but better there than the engine!
 

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A thermal clutch fan will move more air than an electric. A shutoff vlave in the heater hose between the intake and firewall will send more of the hot coolant to the radiator. Don't get the cheaper non-thermal clutch.
 

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Without making mods, since its not an everyday occurrence, turn the heater on and stick a 20# bag of ice on the floor in front of your seat. :)
 

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This is a classic example of the car producing more heat than it can get rid of. Surprisingly, this happens even at idle.

There are several factors involved, some of which were mentioned by the above members. The thing required here is "reserve cooling capacity". What this means is that your cooling system has enough capacity to handle any situation it can experience, and still have a little more to give. This usually means a larger radiator since that is the way BTUs are transferred from the engine to the air.

Most people want more power, and more is never enough. Even though 400hp is more than enough for any "legal" street situation, they want 600hp. Why don't people think about larger radiators? This is a well used pun, but I'll use it again anyway: Because it is not cool!

While the above members have mentioned several Band-Aid solutions, that may solve your issue, the final fix is more cooling capacity, via a larger radiator with a fan & shroud that matches it.

Resist the urge to put in a cooler thermostat, because this won't do anything if you can't cool with your current setup. Once you are past 190, having a 160 is moot since both are wide open at that point. They will argue that if you keep the motor at 160 to start with, you are less likely to run into problems, but this is flawed in the big picture. Yes your starting point is lower, but you will still eventually overheat due to lack of cooling capacity. And the engine is designed to work at 190, which also promotes more complete combustion of the fuel/air mixture.

If you have the original radiator, this may be a good time to replace it with at least a 3-core model and put this problem to bed for good. :)
 

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What is a good recommendation for "a real fan" and who sells them? I know I am going to have this same problem. Thanks,

Bob
 

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jegs, summit, late model restoration, mustangs unlimited, autozone, advance, o'reilleys, ect, ect.... measure the diameter of your fan and get a 5,6,7 blade HD flex fan in the same diameter. bolt on with factory bolts and spacer.
 

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Monday I just ran a local 4th of July parade. It was about 1 1/2 hours from line up til the end. It was in the high 70's-low 80's.

I watched the guage creep up to about 3/4's. At the end of the parade I left it running and got out and opened the hood. I had recently installed a radiator cap with a thermometer on it. It was just under 200°. I figured this was ok as it never went any higher.

I have a stock '65 289 2v with a 3 row copper radiator, a 180° thermostat, a fan shroud with blades half in and half out and a 17" 7 blade flex fan.

For what ever reason Mustangs seem to run on the warm side. Other later vehicles with 289/302 deriviatives do not seem to suffer from this same situation. I do not know why it is that way. The other issue is heat soak after shut down. This seems to be more excessive than later versions, as well.

I also ended up putting a tubular SS coolant recovery system on it to keep from dumping coolant when this occurs.
 

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jegs, summit, late model restoration, mustangs unlimited, autozone, advance, o'reilleys, ect, ect.... measure the diameter of your fan and get a 5,6,7 blade HD flex fan in the same diameter. bolt on with factory bolts and spacer.
Those flex fans are crap, the stock 4 blade moves much more air than one of them! I can tell that just from how must dust the stock fan blows off the garage flow when I rev it compared to the flex fan. The flex fan specifically "saves horsepower" by moving less air.
 

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There are ALOT of options as mentioned above. What I did is flushed my system. Use my heater when need be and have a eletronic pusher fan.
That has worked for me.
 

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Those flex fans are crap, the stock 4 blade moves much more air than one of them! I can tell that just from how must dust the stock fan blows off the garage flow when I rev it compared to the flex fan. The flex fan specifically "saves horsepower" by moving less air.
i guess i'll have to get rid of mine! i thought it was doing a good job.....keeps the 408 at roughly 180-185 in traffic. guess i was wrong.:hihi:
 

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The basic problem is that the slower the engine turns, the slower the fan turns = less air flow. You can solve it a little by shifting to neutral as much as possible and increasing engine speed. You could also put in a larger cooling system (radiator and fan). I choose to use an electric fan that runs at maximum air flow any time it is on, with a modern aluminum radiator. So far, so good.
 

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I know lots of people like to keep it stock but aluminum radiators cool more quickly then copper or brass will because they have a greater surface area than copper ones. Pairing an aluminum radiator with an electric fan that's heat activated (not mechanically activated) will keep your engine plenty cool
 

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When an engine overheats at low speed it is because at that speed there is either:
1. not enough air moving over the radiator to get rid of the heat
or
2. not enough radiator to handle the heat of the engine
If it does not heat at higher speeds then you have enough radiator so that leaves air. Anyway you can get more air through the radiator will help the problem - so will going to a larger (more core) radiator. Since fans are a lot cheaper than radiators try that first. A 7 bladed fan that is 17" in diameter will be better than your 4 bladed fan. The stainless steel flex fans that are rated for 10000 rpm are better than the smaller fiberglass flex fans and won't fly apart. Duct work to get the air to the radiator and then to the fan are also important - as is the exit point of the fan in the shroud. The blades should not be completely covered by the shroud - some of the air that the fan pushes goes out around the fan rather than back - especially the high camber (more curved) bladed fans. As mentioned earlier about half the blade in the shroud and half out is best. This pulls air through the radiator and shroud and then lets it go up, down, and all around as well as back from the fan. If the blades are completely covered then some of that air get recirculated back through the fan and reduces the amount of air through the radiator.
Ideally a shroud should fit within a few thousandths of an inch around the fan - THAT IS NOT PRACTICAL in a car and that level of efficiency is not needed. 1/4" to 1/2" clearance is necessary unless the engine is solidly mounted to the frame. If you keep the mounts in good condition and have no frame twist then less clearance is better. For those of us who live in the real world a good sized radiator and a flex fan are adequate to keep the horses cool under almost all conditions with no more than a 50/50 mix of water and anyifreeze.
 

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i guess i'll have to get rid of mine! i thought it was doing a good job.....keeps the 408 at roughly 180-185 in traffic. guess i was wrong.:hihi:
I'm not saying they don't work, only saying that they're not as good as a stock fan at cooling. Their benefit is the reduced horsepower drag as RPM increases. Most of us need more cooling and care less about the 10 horsepower we theoretically lose! lol
 

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At low rpm the only hp savings is in the weight difference between the flex fan and that heavy steel stamping the factory put in. The amount of air moved by the higher cambered stainless steel blades is a lot higher than the amount of air moved at an idle with the factory fan. The much larger and even heavier thermostatically controlled fans are nearly as efficient at idle but save a lot more power than the flex fans at higher rpm. It takes a lot of hp to bend those blades but they move more air than is needed at higher rpm. They do keep the air moving though.
 
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