My 69 Camaro came with an aluminum radiator and also aluminum Edelbrock heads and intake. The system currently has the overflow hose running down to the ground which i am assuming was the way they came from the factory or am I wrong?
I read somewhere that aluminum parts need to have a closed system so no air gets in, can anyone tell me if this is correct? Will there be problems having an open system? Should I be running a closed system with these aluminum parts or does it not matter will be fine with the current open setup?
If it should be closed I could buy a cheap recovery tank from Pepboys for now, but what pressure cap would need to be used?

thanks for the help

I am of the understanding that alum goes away because of the use of dis-similar metals. Iron block-alum heads, iron heads-alum intake etc. All cooling systems are closed ot they would not pressurize. The overflow or catch can is designed with the environment in mind.

You don't want trapped air in your block or heads as it can create a hot spot but our old cars always work with about the top two inches of the core being air. They only purged if over filled ot there was a problem causing the pressure to build too high. Modern cooling systems using fluids like GM's Dex-Cool require no air at all in the system. Dex-Cool reacts with air in a negative way and can clog a cooling system.

I think if you are not running a 10 year coolant you could stay with as designed or add an overflow and plum it to work like a modern system, it's your call...

thanks, what i ment by open was that there was no recovery system attached. But like you said, air is still present

I guess I don't understand how the current system works. How does the system built pressure with not pressure cap? Does the air designed to be left at the top help or something? How much pressure is in the system? I am just used to recovery systems and never really saw a cap like my radiator has the over flow hose not connected to anything.

So basically the air won't cause problems with the aluminum, it the choice of coolant and which system its paired with. I read that it might be better to use a newer HOAT coolant like Zerex G05 with all the aluminum parts, so i guess that would mean that this coolant should be used with a closed recovery tank and not my current system. I have no idea what the previous owner put in the car(coolant is like a transparent pink), but I was planning on flushing out the system for a new coolant and want to make sure i run the right coolant and system that will perform and last. thanks again

Both systems have pressure caps, the modern system has a pressure cap and a recovery tank. As the engine heats up the cooling system some fluid will be purged into the recovery tank by design. As the system cools the fluid is drawn back into the core. This is how it insures no air gets into the system.

During normal maintaince you top it off the system via the recovery tank and it's marked with a hot and cold level. If you change the fluid or replace a hose then you would fill the system by removing the pressure cap just like checking a radiator on our old cars. There are purge screws placed in places where an air pocket can for and you have to fill and purge a modern system to get the air out.

If you convert your classic you can install a recovery tank and then you have use the right type of pressure cap. Some kits give you a washer/gasket that lets your cap not only purge but suck it back as the system cools. The other thing guys do is just add a catch tank so if it burps it doesn't spill on the ground.

Like Dennis said, it's your call. From the INSTANT that I heard of a closed system, I've run one. I remember reading about its development in Mechanics Illustrated. The system was being introduced on new Cadillac’s in 1970, if memory serves me. I went down to my Chevy dealer and ordered the parts. Over the years those parts have changed. Here's a look. The recovery tank is where the battery used to be. And one more thing. I don't think this statement is flame able. There are no cars made in the modern world with open systems. There's no advantage to it, only disadvantages. Hell you can't even drag race if you dribble on the ground.
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