Bright green fluid under your car is traditional ethylene glycol antifreeze - the classic green coolant used in most American cars built before the late 1990s and many newer ones. Here's where to look for the leak and what it costs to fix.
Most common source. Hoses age, crack, and weep coolant - usually at the clamps where they connect to the radiator or engine. New hose: $20-50. Easy DIY job for most cars.
Diagnose My Leak →When the water pump's internal seal fails, green coolant drips from a small weep hole on the bottom. You may also hear a whining or grinding from the front of the engine. $400-700 installed.
Diagnose My Leak →Radiators corrode (older metal) or crack at the plastic end-tanks (newer designs). Look for green crusty residue on the radiator fins or end tanks. Replacement: $300-700 installed.
Diagnose My Leak →A leaking heater core drips green coolant onto the passenger floor and fogs the windshield. Smelling sweet inside the cabin? Heater core. The dash usually has to come out to fix it. $800-1,500.
Diagnose My Leak →On older V6 and V8 engines, the intake manifold gasket can leak coolant externally or internally. External leaks drip down the side of the engine. $300-700.
Diagnose My Leak →Describe what you're seeing and our AI mechanic will tell you what it is, how serious it is, and what it costs to fix - in seconds.
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A coolant leak that affects engine temperature can trigger the check engine light. Here are the most common related codes.
In a car, almost always yes. Green ethylene glycol coolant is the traditional formula used since the 1930s. Some windshield washer fluids are green too but those won't pool under the car the same way.
Don't. Different coolant types use different chemistry and mixing them can create gel-like deposits that block the radiator. If you need to switch types, drain and flush the system first.
Traditional green ethylene glycol coolant should be replaced every 30,000-50,000 miles or every 2-3 years. Modern long-life coolants go 100,000 miles. Old coolant becomes acidic and corrodes the cooling system.
Someone added the wrong type at some point. Schedule a coolant flush and refill with the correct color for your car. Mixed coolants don't protect the engine as well and can cause corrosion.
Tell our AI what you see under your car. You'll know what it is, whether it's safe to drive, and what the fix costs - in under a minute.
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