Thread: Should I have an overflow bottle on my radiator?

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Yeah, I know, another simple question. When you guys are done teaching me, I will know everything.

My overflow tube just runs to the ground. Should there be a overflow bottle? Will it draw back into the radiator when it cools?

Thanks Jim

Yeah, I like them because they keep your car from doing that embarassing puking of water when you shut it down sometimes, plus you don't keep losing coolant.

Just make sure you get a cap designed for closed systems, as they are made to allow water to travel back into the radiator when it cools down.


Don

Thanks Don.

There is a difference between an overflow bottle and a coolant recovery. An overflow bottle will just fill up and then overflow, it will not draw back into the radiator. A coolant recovery system will. It is set up different

I like the coolant recovery system. How do I set that up?

Jim

The coolant recovery system is definitely the way to go. One major benefit is less corrosion inside the engine, because the radiator stays completely full, minimizing air (and oxygen) from getting into the water, so there's less oxidation, and your anti-freeze will last longer.

The radiator cap needs to have a good seal at two places. The spring loaded lower seal provides the pressure in the radiator, which increases the boiling temperature of the coolant. Because the radiator is completely full, and the coolant will expand as it gets hot, some coolant will be forced past this seal into the overflow reservoir.

The upper seal, inside the cap, seals around the top of the radiator neck. When you shut off the engine, the coolant will contract as the engine cools off. This upper seal forces the coolant in the overflow reservoir to be sucked back into the radiator thru the one way check valve in the bottom of the cap as the engine cools off. If this upper seal isn't good, air will be sucked into the radiator rather than pulling the coolant from the reservoir. Of course, the overflow tube must go to the bottom of the reservoir so it can stay submerged in the coolant.

It's simple, cheap, there are no hi-tech gadgets, and no puking! What a deal!

Jim: Yeah, I wasn't even thinking "overflow bottle" because generally the only places you see these are on drag cars, and usually mandated by the track to keep you from spilling coolant all over the track. These were simple bottles that were kept empty, and if your radiator spilled water out the tube, it just trapped it and kept it there.

Coolant recovery tanks are similar, but these are what you see on new cars, where the water will still spill out into them, but once the system cools back down the coolant will siphon back to the radiator.

You ask about sources. You can go as simple as the $ 8.00 ones from Autozone, or similar........or if you want pretty, one of those cylindrical aluminum or stainless ones you see all the hot rods running on the side of their radiator. Cost isn't too bad on these, I think in the $ 50.00 range(?).

Don

Thanks Guys, couldnt do it without you!

Jim

Don't you have to use a radiator cap designed for a coolant recovery system? It seems that when Iwas in school (many years ago) we were told that was a requirement.
Jim

Yes, they are considered for use with a closed system. Tell the parts guy that info.



Don

won't have to tell the parts guy that, unless your getting an original cap from a resto company, they have the valve, it's standard to have them now days. it's a little silver thing on the bottom of the spring, you can pull it out by hand