If your car’s radiator strikes you as one of its least understood components, it’s more than likely because it’s performed its job reliably enough to remain unnoticed. It’s responsible for everything, from keeping you and your passengers warm in the winter, to keeping your engine and transmission cool in the summer.
And with regular maintenance, it can go on faithfully doing so for decades. But make no mistake, though, when it goes bad, it can develop a leak, become clogged, begin to rust. If something like this happens, you’ll want to get ahead of the situation quickly before it leads to something far worse. With that thought in mind, let’s take a look at what’s behind a radiator’s quiet reliability, and what to look out for when it decides to reveal itself for all the wrong reasons.
Simply stated, the purpose of your car’s radiator is to dissipate the heat that’s absorbed by the coolant circulating through the engine. The radiator itself consists of a densely packed core of fin-covered tubes that exchange heat through airflow. Once the coolant passes through it, it’s returned to the engine through the water pump.
It’s an endless cycle of heat transfer that occurs in all seasons and under extreme pressures, so you can imagine just how durable car radiators need to be to perform this task efficiently. And it’s not just your engine that’s relying on the radiator’s reliability. If your car has an automatic transmission, it’s very possible that your radiator also contains separate tubing that transmission fluid to circulate through.
Thanks to their simplicity though, it’s not uncommon for radiators to last for years without problems, and high-quality aftermarket radiators are built to even more exacting standards than OEM models. The reality, however, is that all radiators do eventually fail, and it doesn’t usually begin with a bang, it’s with a whimper. Warning signs to look for are:
- An engine coolant temperature gauge acting erratically,
- White smoke or steam coming from under the hood,
- Hissing sounds coming from under the hood,
- A sweet smell inside the car,
- Green, red, or milky brown liquid accumulating under the car.
While these indicators may not point directly to the radiator, they are cooling system problems. Even if they don’t immediately involve your radiator, they will very soon. Let’s look at each one briefly, so that there’s no confusion about when it may be time to consider replacing your radiator.
With a 50/50 mixture of water and antifreeze coolant, an engine’s coolant temperature will normally reside around 90ºC. That’s hot enough to serve its purpose, but not hot enough to boil. Temperatures that fluctuate drastically when driving, or are persistently high, indicate that there’s a blockage in the coolant system.
The first thing to do is stop the car immediately before serious engine damage has a chance to occur. The engine thermostat may be stuck, the radiator’s cooling fins may be blocked or bent, or the radiator may be clogged. For most radiators, after they’ve reached a certain age, have gone through fin repairs, and unclogging stops being feasible, replacement becomes the best option.
Smoke and steam
We’ve all passed cars sitting on the side of the road with steam pouring from under the hood. This is another “stop the car immediately” scenario because the cooling system has stopped working completely. A punctured hose or a cracked radiator are the likely culprits, but if earlier temperature warnings have been ignored for too long, the damage could be worse. Hopefully the problem stops at the radiator, and getting a new core will solve it.
Your temperature gauge may not have moved beyond where it’s supposed to be, but there’s no mistaking the raucous sound of hissing coming from under the hood after you’ve turned the car off. It’s coolant “boiling-off” likely from either the overflow tank or the radiator cap. In case the system’s gotten hot enough to sound off, there’s a component in it that isn’t doing what it’s supposed to do. A stuck thermostat, a bad radiator cap, or a blockage accumulating inside the radiator itself are almost sure to be the blame.
A sweet smell
As unlikely as it may seem, your car’s heating system is actually part of the cooling system. When you turn the heater on, heated coolant from the engine circulates through a heater coil under the dashboard before being going to the radiator. And if you’re suddenly picking up the curiously sweet scent of coolant in the passenger compartment, then there’s a leak somewhere in the cooling system. In spite of its sweet smell, the chief component used in coolant, ethylene glycol, is lethally toxic if ingested. If you’re smelling it, you want to get the entire cooling system checked out as quickly as possible.
Liquids on the ground
There isn’t much left to diagnose when you’re finding pools of liquid sitting under your car. If it’s not oil or condensation from the air conditioner, it’s a coolant leak. Green or red liquids, the common coolant colours, are easy to identify, but milky brown’s a more ominous find. It’s coolant that’s mixed with something else, and it could be with sludge, rust, or scale that’s been building up in the radiator. Or it could be with engine oil or transmission fluid… which is really not good. As a minimum, the radiator will need to be flushed out, but you may be looking at replacing it.
The final word
For all their simplicity, when you stop to consider the role radiators play in the cooling system and other systems, it’s amazing how inconspicuous they’re able to remain. In all fairness, they’re not an engine’s only means of heat dissipation – the exhaust system has its role to play too. However, car radiators are the real temperature tamers, and you don’t want to take them for granted.
If your radiator’s seen its better years, or you’ve seen any of the symptoms above, now may be the time to consider replacing your old, worn out one with a new unit. It’s an investment in the life of your car.