Why do heater cores fail

You might also smell this lovely smell around the outside of your car, which means it's time to look underneath your vehicle and see how much of that coolant has spilled out onto the ground. A very common tipoff to a heater core problem is the inside of your car suddenly fogging up for no reason. This fog is caused by warm coolant leaking into the cabin of the vehicle and evaporating into steam as it hits the cooler air inside your car.

When a hole or puncture develops in the heater core, all that warm air may escape too quickly to reach you at the other end of the heater ducts.

Depending on the size of the puncture, you might feel mildly warm, lukewarm, or absolutely freezing air coming from your heater. If you find your vehicle has suddenly been needing a higher than usual amount of coolant and you cannot figure out why, it could be a blown heater core.

If the leak is hard to find, the coolant may leaking into your cabin when the system is cold, and instead of making fog, is creating a puddle. Check the passenger-side floor to see if it is wet.

But lab tests show that its anti-corrosive properties start to degrade as soon as months after installation. In fact, since the aftermarket companies try to cover their basses by adding materials that protect aluminum, cast iron, magnesium, steel and plastics, they wind up with a formula that can actually accelerate corrosion damage on some of those parts.

If other words, some anti-corrosion additives that protect aluminum can accelerate corrosion when they come in contact with cat iron parts, and vice versa. Avoid the all makes, all models formulas and buy the EXACT coolant recommended by your car maker and change it according to the maintenance schedule.

For more information on coolants, see this post. Avoid twist the rubber hoses to remove from the heater core tube.

Excessive force can damage the solder joints, causing a leak. Most professional mechanics scoff at the idea of using a cooling system sealer to stop a heater core leak. Many times those sealers cause far more harm than good. You want to use the least amount of sealer product, which is just the opposite of what most DIYers do.

Skip a few radiator flushes and the particles of rust and other debris that would get cleaned out increase in both size and amount.

Even if your radiator can survive with minimal maintenance, the heater core, with narrower passages, will clog up sooner. The core may not be the issue, though, as other things like a fuse, the cabin air filter and the fan or vent doors could be the culprits. Rule those out first because, as you can see from the picture above, getting to the core is a big job. Even if your leak is as small as a pinhole, the coolant could be coming out of your core in a fine mist. Other clues for a faulty core include a sticky residue on your windows, dashboard, steering wheel or other surfaces inside your car.

Another reason for a bad heater core could be because of a leak somewhere in the system. Find a local car repair shop to properly diagnose your car issues to be safe. Here are the most common signs that your heater core is going bad and things to look out for in the future:. If you smell the sweet smell on the outside of your vehicle, check to see if you have a leak going on under your car.