Honda Shadow Radiator Overflow - How Many Hoselines?

on August 01, 2019

A customer asks, "Does my Honda Shadow’s radiator overflow tank need BOTH an outlet and inlet hoseline?" We get this question a lot so we’ll break it down for you.


Understanding your overflow tank

We’ll start by explaining the function of your radiator’s overflow tank in order to better understand it. As engine coolant heats, it expands and builds pressure. When that pressure exceeds a predetermined level, the excess coolant is transferred into the overflow tank. As it cools, it contracts and the pressure drops, forming a vacuum. That vacuum will then suck the previously emitted coolant back into the system (this way you don’t end up with air in the system).


Attaching the hose(s)

On a Ucor Tank (Universal Coolant Overflow Reserve Tank), you’ll find a fitting on the underside of the cap that will allow you to attach a fuel line or hose to it. There’s usually a line that goes back down your backbone to the stock overflow tank—you’ll want to take that off and run it to

where you’re planning to mount your Ucor Tank, and clip off about 6.5 in (cut the end at an angle). Once it’s ready, slip on a barb fitting inside the cap and screw it on.


Now, the system is sealed so when everything cools off (the coolant contracts) there’s negative pressure. And the radiator cap is going to allow the excess coolant to be pulled back into the system. It’s important you have coolant in your overflow tank and in your radiator because air in the system will contribute to corrosion.


Your coolant system is set up with the cap for a specific reason: it opens to allow the expanded fluid to go into the overflow tank, then it’ll close. Once the right amount of pressure is created in the overflow tank, it allows the coolant to come back in. It’s a great system.


So… one or two lines?

Bottom line: no, you don’t need two lines. There’s only one line for overflow coming from the filler. You just need the one line going to the top fitting and a return line going in on the other side of the cap. The caps are also vented so when the system pushes fluid in or pulls it out, air can get in and equalize the pressure.


Replace your Honda Shadow’s stock overflow tank with a beautiful Ucor Tank (it fits other bikes too)! Get yours HERE!


 TJ Brutal Customs Ucor Tank - Universal Coolant Overflow Reservoir


For more details on this process watch this video:


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