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Why Is Green Fluid Leaking From a Car?

Green fluid puddled around car tire

Imagine it’s a beautiful, sunny day and you’re in a good mood. As you walk up to your car, you notice a green puddle underneath it. Uh-oh. What could green fluid leaking from a car mean?

This shouldn’t take too much detective work to figure out, as the only green fluid in your car is coolant. But if it’s on the ground, it could be a sign that something’s wrong. Here’s how to check where that green fluid is coming from.

A Hose Situation

Man pouring antifreezeFirst, you’ll want to check your hoses, but be sure to do this while the engine is cool. Look for the hoses leading to and from the radiator. Check for any cracks or discoloration (especially green-tinged discoloration). Then, grab the hose with both hands and gently twist. Does the hose seem brittle? Do parts crack or flake off? Is your hand a little damp (or green)? You may have found the problem.

This is the simplest reason for green fluid leaking from a car and the easiest to fix. If you already do basic maintenance on your car (oil changes, etc.), installing a new hose is an easy DIY job.

After you’re done, remember to top off the coolant tank — you’ve lost some and the car’s engine needs every drop of protection.

The Hoses Are Intact — Now What?

If the hoses look good, then the problem is elsewhere. Start the car, then look underneath while it’s running to see if the coolant starts leaking, how much fluid there is and where it’s coming from. (Don’t touch anything — it gets hot down there.) What you’re doing at this point is trying to narrow down what you’re going to tell your mechanic. Use your cellphone to take a video of the leak.

If you can’t see a leak, don’t assume it’s not your coolant on the ground. Check the coolant overflow tank. If it’s below the fill line, top it off, run or drive the car for a bit and check the level again. If it drops noticeably, there’s a problem.

What Else Could It Be?

Assuming the hoses and connections are okay, this is likely a corrosion issue — the radiator itself or, more commonly, the core plug needs to be fixed or replaced. To solve the problem, call your mechanic, as engine damage from coolant loss is worse than merely getting your radiator flushed.

Once you’ve got this handled, make a point of checking your coolant reservoir and other fluids every week or so. That should help you spot issues while they’re still small.

Check out all the coolant products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on fluid leaks, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

Mike Hagerty View All

Mike Hagerty is an automotive journalist whose work has been featured on radio, TV, in print and online since 1997. He's the Publisher and Editor of, and contributes car reviews to the Los Altos Town Crier and Previous outlets have included KFBK and in Sacramento, California, the ABC television affiliates and Hearst-Argyle and Emmis radio stations in Phoenix, Arizona; AAA magazines for Arizona, Oklahoma, Northwest Ohio, South Dakota and the Mountain West and

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