Radiator leak

Symptoms

• Puddle or wet spots directly under the radiator (front of the engine bay)
• Visible crusty or discolored residue on the radiator itself
• Coolant level dropping steadily
• Possible steam from the front of the car

Likely causes

• CommonCorrosion from old or wrong coolantCoolant that's overdue for a change loses its corrosion inhibitors, allowing internal rust and pitting.
• CommonDamaged radiator seam or tankPlastic end tanks and the seams where they meet the metal core are common failure points as they age.
• PossibleImpact damage from road debrisRocks or debris can puncture the radiator, especially on vehicles with limited underbody protection.
• PossibleFailed radiator cap sealA worn cap seal isn't the radiator itself but can look like a radiator leak, weeping around the cap area.
• Less commonCracked plastic fill neckThe plastic neck where the cap seats can crack, especially in older vehicles.

What to do

1. Check with the engine cool for wet spots or dried coolant residue specifically around the radiator core and end tanks.
2. Check the radiator cap and its sealing surface for damage, since a bad cap can mimic a radiator leak.
3. Top off coolant temporarily if needed, but plan for a proper repair rather than repeated top-offs.
4. Avoid driving long distances if the leak is significant, since radiator leaks can worsen and lead to sudden coolant loss.
5. Have a mechanic pressure-test the system to confirm the radiator is the actual source.
6. Get the radiator repaired if the damage is minor and repairable, or replaced if it's more extensive or old.
7. Flush and refill the system with correct new coolant after any radiator repair or replacement.

Tools and parts

• Flashlight
• Gloves

When to call a pro

See a mechanic to confirm the radiator is the source and to handle replacement, since most radiator leaks aren't practically DIY-repairable and need proper flushing after the fix.

Safety