5 Causes of Antifreeze Leaking

A radiator filled with antifreeze.

If you detect antifreeze leaking from the engine of your car, the wise move is to get it taken care of as soon as possible. A 50/50 mixture of antifreeze and distilled water flows around the engine during use, keeping it from overheating, so a leak can mean trouble. Eventually the radiator and the reservoir will run dry and lead to the destruction of the engine. While detecting a coolant leak can be difficult, there are a few places to immediately look.

1. Radiator Hoses

The hose that runs into or out of the radiator may be the culprit. Hoses crack and split with time, so closely inspect the length of your hoses for any damage. Hose clamps that connect the hoses to the radiator can also fail with extended use. These replacements can be made without professional help so long as you know how.

2. Radiator Cap

The radiator cap is found on the top of the radiator. If damaged or if its seal is broken, it will no longer contain the pressure built up inside the radiator, causing fluid to leak while the vehicle is running.

There are several things to check for when trying to figure out whether your radiator cap is the source of a coolant leak. Start with making sure that the cap has the proper pressure rating for your vehicle. Obviously, the cap doesn’t have to be damaged to be causing a leak if the pressure rating is not correct for your radiator.

A bad seal on the radiator cap can be spotted with just a visual inspection of the main seal, pressure, and valve seal. Also, the spring in the cap should have resistance, and if there is none, it needs a replacement.

If you’re still sure your radiator cap is the problem, but have yet to find an apparent issue, you can test it with a professional pressure testing device if you have one available.

3. Reservoir

This plastic container is an overflow reservoir for heated antifreeze and water. Should it have a small crack or hole, coolant will gradually leak out, so a damaged reservoir will need to be replaced. A new coolant tank can be found at any auto parts store for cheap, and they are fairly simple to install.

4. Radiator

It could also be that the radiator itself is leaking. If all the parts listed above have checked out fine, then it’s time to take your vehicle in to a shop. This problem will require a costlier, more involved fix that’s best left to a mechanic.

5. Other Possible Causes

Other possible causes for an antifreeze leak include a damaged or faulty water pump, intake manifold gasket, or heater core, all parts of the coolant system. Like with a radiator replacement, these parts should be inspected and repaired by a pro.