Thread: Radiator overflow tank

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Can someone tell me if a small spun aluminum fuel tank will work as an overflow tank for my radiator? One fitting on bottom and a vented cap will let water from radiator go in and out of overflow tank, right???

Ive seen these small tanks mounted in front of radiators at car shows, so I know they work and are cool looking. Just need to know if I need another fitting for a vent.

Thank ya

the tank no mater what it is needs to be vented. But your return line needs to be in the bottom of the tank. Through the top with a tube or a fitting on the bottom.

One fitting on the tank bottom and a vented cap will let coolant overflow into the tank, and then be sucked back into the radiator as it cools provided you have the right cap on the radiator to allow back flow. However, if the tank gets full the vent is not going to support overflow. As long as you keep the cold fluid level low in the tank you should be OK, but if you want to be sure add a second fitting with a standpipe in the tank so that anything above the standpipe gets blown out.

Originally Posted by rspears

One fitting on the tank bottom and a vented cap will let coolant overflow into the tank, and then be sucked back into the radiator as it cools provided you have the right cap on the radiator to allow back flow. However, if the tank gets full the vent is not going to support overflow. As long as you keep the cold fluid level low in the tank you should be OK, but if you want to be sure add a second fitting with a standpipe in the tank so that anything above the standpipe gets blown out.

Explain what you mean by the right cap on radiator. Are you talking pressure or a small rubber hose coming off the neck where cap goes on?

Originally Posted by Babyburr

Explain what you mean by the right cap on radiator. Are you talking pressure or a small rubber hose coming off the neck where cap goes on?

The old style caps were made to burp out through the tube to the ground, but would suck air through the path of least resistance, as there was no seal between the cap and the top of the filler neck. Caps that are made to work with an overflow reservoir, where the radiator pukes through the tube, and then sucks back through the tube as the system cools and creates vacuum, have a gasket in the top to tightly seal the cap to the filler neck and pull down tight.

If you need a visual of the correct style of cap, here you go.

Alright, thanks guys.

Originally Posted by sprayed99

If you need a visual of the correct style of cap, here you go.

Indeed that cap is the right style, with a spring loaded gasket down in the neck to establish the designed system pressure, i.e. 18psia or 16psia, and a second gasket at the cap to neck interface to ensure coolant pullback through the hose; BUT you don't need a fancy billet cap to be right. A basic STANT stamped steel cap that has the cap to neck gasket works just fine, too. One works and looks like $1MM, and the other just works.....

Spun aluminum...............ehhh!

Another way to vent is how this one is set up. Tube into the bottom for the hose from the rad neck, and a second tube in the bottom that extends almost to the top of the inside to act as a vent. If you're puking more than a quart you've got bigger problems.

Yeah, I know. The main reason I'm using a small spun aluminum tank is to fill in the big gap in front of my radiator. It just doesn't look right with the big open space.