Can a car radiator explode?
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Not quite, but they can burst, crack or warp under extreme conditions. Here’s why, and what to do about it.
Radiators can’t exactly explode in the traditional sense of the word. If you’re worried about an explosion of fire and shrapnel coming from your radiator, you can rest easy because the possibility of this occurring is extremely unlikely.
Radiators can, however, explode in the sense that they crack open or burst in a dangerous splash of hot coolant when under extreme pressure and temperatures. If this happens to your radiator, it can cause catastrophic damage to your vehicle and pose a serious threat to your safety.
But don’t panic. Even a dodgy car is a pretty advanced piece of machinery, and there will be signs of an impending problem well before your car’s radiator actually does crack or burst. Signs to watch out for include:
- The temperature gauge on your dashboard rising past its midway point
- A warning light popping up on your dashboard
- Rattling noises coming from your engine
- An awful burning smell filling up your car
- Leaking coolant (you might notice brightly coloured coolant puddles under your parked car)
- Steam blowing out of your radiator, or if there’s steam puffing out from under the hood
Fortunately, none of these signs are subtle, so you should be sufficiently warned when there is a problem. Still, there are rare instances when a radiator can burst or crack without much warning.
In this guide, we’re going to explain some of the common reasons why vehicle radiators might burst or crack. Ultimately, the reason always comes down to too much pressure building up in the radiator, but knowing the specifics of the problem can help you decide if you want to fix things before they become a worse issue.
Natrad is Australia’s most trusted radiator repair specialist group. We’ve been taking care of Australian drivers for 40 years. If you’re worried about your radiator bursting or about your car’s cooling system in general, you can leave it in our hands.
5 reasons your car radiator might burst or crack
1. A clog in your radiator is building up pressure
Radiator fluid that is not providing corrosion protection can allow rust and sediment to accumulate inside the cooling system. This buildup can create a clog in the radiator tubes and inhibit the flow of coolant.
The poorer the flow of your coolant, the hotter your engine will run and the worse your car will drive. And if you have a totally clogged radiator, then it’ll start to build significant pressure. That pressure is liable to cause a burst somewhere in your radiator or cooling system, likely while you’re driving.
The thing is, this build-up of sediment can be treated. Debris can take 3-4 years to build up to a noticeable level, which is why it’s best practice to have your radiator flushed and cooling system filled with a good quality coolant that provides long-lasting corrosion protection.
If it’s been a while since you’ve changed your fluid, it’s actually quite easy to do yourself. Here’s a handy video to teach you how to top up your radiator coolant at home.
2. A faulty radiator cap isn’t relieving pressure
A radiator cap isn’t like a bottle cap — it’s not just used to open and close a hole.
A radiator cap is actually a valve that regulates the pressure within the radiator. Without getting too technical, the hotter your engine becomes, the more pressure builds within the radiator. Coolant operates best under a certain level of pressure, and the radiator cap keeps that pressure in check.
If your radiator cap is faulty, damaged, corroded or the wrong type for your vehicle, then the pressure within your radiator can build to a dangerous level.
The radiator cap is easy to find and inspect. It will usually be quite obvious if there’s a problem with it. If your radiator cap seems janky or damaged, you can simply buy a replacement cap. However, it is important to choose one with the correct size, pressure rating and recovery mechanism for your vehicle.
3. Corrosion and road damage are wearing away components
When radiator corrosion occurs, sediment builds up in the coolant — just like we covered earlier. However, instead of clogging up, sediment can also coat the surface of metal parts in the cooling system which prevents corrosion inhibitors in the coolant from protecting that surface. Without protection, these metal parts (such as radiator tubes, fittings and other cooling system components) can be eroded to the point of failure.
But there are other ways your radiator can be damaged. Driving over rough and rocky terrain can kick stones up under your car, which can chip, dent or even crack your radiator tank or tubes.
One common cause of unseen and easily ignored damage is when drivers ignore minor accidents. Damage after an accident mighty appear minor externally, but internal damage can be a lot more extensive. Under the hood, your car’s radiator could have experienced significant damage or even have had parts come loose.
A damaged radiator tank is a disaster waiting to happen — but it’s an easy one to avoid.
Our recommendations: Always get your radiator checked after an accident, no matter how minor. Get your radiator flushed to clear out any debris and replace your coolant with a good quality product that offers a long service life.
4. A leaking head gasket is losing coolant
The head gasket is a connecting component that sits between the engine cylinder block and cylinder head. The head gasket seals the cylinders, and one of its jobs is to prevent coolant from leaking into them.
Head gaskets fail when they’re overwhelmed by the heat and pressure of the engine. For that to happen, it likely means there’s already a problem with your cooling system, which the blown gasket will exacerbate. Without sufficient coolant, your engine will rapidly overheat.
There are obvious signs indicating when your engine has blown its head gasket. These can include: white smoke billowing from your exhaust, bubbling in the radiator coolant reservoir, unexplained coolant loss without visible leaks, milky discolouration in your oil, oil present in the coolant and your engine frequently overheating.
A busted gasket isn’t something you can fix at home unless you have the appropriate experience. We strongly recommend you take your car to a reputable mechanic.
5. A faulty thermostat and inaccurate temperature reading
Every car has a temperature sensor attached to the engine to keep a check on it. Most cars also have an engine temperature gauge on their dashboard, which gets its reading from the engine temperature sensor.
If your thermostat is faulty, or if there’s a broken connection between the sensor and dashboard gauge, then you may not even know if your engine’s overheating until it’s already in trouble.
At that point, you’ll likely notice a hot or burning smell and/or feel your engine losing power.
Trust your senses and intuition. If your temperature gauge is reading normal, but there’s a burning smell in the car, if your car just doesn’t seem normal all of a sudden, or if there’s unusual sounds coming from the engine, then your car needs urgent attention.
What to do if your car radiator ‘explodes’
Immediately pull over to the side of the road and put on your hazard lights. Turn off your engine so that it can cool down. If you want to see what’s going on under the hood, DO NOT touch or tamper with any of the components until the engine has had enough time to fully cool down.
If your radiator bursts while you’re standing in front of it with the hood open, you’d be standing right in front of a major splash of coolant and steam bursting at temperatures that can exceed 100°C. This can cause severe burns and necessitates immediate hospitalisation. Therefore, the safest thing to do if you suspect your radiator is overheating is to first let it cool.
We strongly recommend that you call your roadside assistance provider or a tow truck to get your vehicle off the road and to your nearest Natrad or vehicle repair workshop.
What to do if your radiator hasn’t exploded, but coolant is leaking out
If you’ve noticed your radiator leaks coolant but don’t know why, you should take your car to a Natrad workshop if there’s one nearby.
It is possible to drive your car with a radiator leak, though you do have to be careful. Frequently check your temperature gauge, and be prepared to pull over and let your car cool down if it starts to read too hot.
You can attempt to patch the leak temporarily using leak-repair fluid or sealer. If you don’t have any spare coolant, you can top up your car radiator with water. It’s not ideal, but it may help your car last until you get to a radiator repairer.
If you’re anxious about the state of your car’s radiator, then nip into Natrad. Our radiator specialists will give it a thorough check so you and your loved ones can drive with total peace of mind.
