How to maintain your radiator in winter? Our winter auto radiator maintenance tips

maintenance tips for auto radiators

maintenance tips for auto radiators


Icy mornings, cold nights, harsh winds and rain mean it’s well and truly winter in New Zealand. Although New Zealand overall might not get as cold as other parts of the world in winter, we can still experience problems. Unfortunately, we’re also not the only ones who have problems when the weather turns nippy – we also need to keep our vehicles in mind in winter by making sure they stay in top working condition in the cold. After all, there’s nothing worse than being stranded somewhere on a cold, dark winter’s night because your car is taking a sickie.

When temperatures drop, all sorts of problems can befall your vehicle. One of the most serious wintertime mechanical faults is a frozen engine. Cold weather can put your vehicle under a lot of stress, especially it’s radiator and cooling system. A properly functioning radiator and cooling system, with the right coolant/antifreeze mixture, is vital for keeping the engine cool without freezing in winter.

How does cold weather affect auto radiators?

If a vehicle’s cooling system hasn’t been properly maintained, it can lead to a lot of problems in the winter months. Fluids can freeze – and even if they haven’t quite frozen, they’ll not be flowing like they’re designed to – and hoses can crack in the cold. Here are just some of the adverse effects of cold weather on a vehicle’s radiator.

  1. If water inside the radiator freezes, it puts a huge strain on the radiator casing and could cause it to crack and start leaking fluid
  2. If the fluid in the cooling system’s lines freeze, they will become blocked and may even rupture
  3. If the radiator freezes, cracks and starts leaking fluid, the coolant fluid could contaminate the transmission fluid, which will damage the transmission.


If the coolant/antifreeze-to-water mixture in the radiator is not right, then the liquid can freeze – if you live in a climate where winter temperatures can drop below freezing, then the accepted ratio of coolant/antifreeze-to-water is 50:50 or 60:40 – (talk to your ADRAD radiator agent about the right ratio for your vehicle and location). While a vehicle’s cooling system is quite sturdy, it’s not designed to handle ice build-up. If water inside the radiator freezes, it puts a huge strain on the radiator casing and could cause it to crack and start leaking fluid. That’s not a good place to be.

Blocked lines

If the fluid in the cooling system’s lines freeze, they will become blocked and may even rupture. Or, over time, they will become so weak that when the summer heat returns and the engine heat up on a long drive, they could suddenly give way, leaving you stranded.

Transmission failure

In vehicles with automatic transmissions, the transmission cooling lines run through a compartment in the radiator. If the radiator freezes, cracks and starts leaking fluid, the coolant fluid could contaminate the transmission fluid, which will damage the transmission. Then not only will you have to repair the radiator but you could also be facing the bill for a transmission rebuild.

OK, so there you have some of the winter scenarios that you can avoid by doing regular auto radiator checks – that way you’ll keep your vehicle’s radiator and cooling systems operating at peak efficiency during the winter and avoid an emergency visit to your ADRAD radiator repairer.

Symptoms – and what to do

But what to do if you’ve been lax and forgotten to do the proper checks, and now suspect your car’s cooling system is giving you the cold shoulder? There are various tell-tale signs of a frigid cooling system – and a number of dos and don’ts to help you avoid inflicting costly engine damage on your trusty (but perhaps neglected) steed.


You turn the ignition on a bitter winter’s morning, only to hear a relentless squealing noise coming from under the bonnet. This might be a sign that your vehicle’s water pump has frozen – the noise could be the sound of the fan belt skidding on the pulley. It may also be a sign that the cylinder block has frozen too.

Or you started up OK and are heading off, only to notice that the engine starts to overheat! This could also be a sign of a frozen cooling system. Even on the coldest winter morning, if the radiator has frozen and the coolant/antifreeze isn’t circulating as it should, an engine will quickly overheat.

What to do

If you experience any of the above symptoms, it’s vital that you switch off the engine as quickly as possible – or risk costly damage to your engine.

Switch off

It’s important not to run a vehicle with a frozen cooling system. While it might sound like a reasonable idea to fire up the engine and hope the heat it generates will thaw the cooling system and get the fluids moving again, this is not a good idea. Without a steady flow of coolant/antifreeze from the start, an engine will quickly overheat and could even explode, due to the mounting pressure from a blockage in the cooling system.


Much better to give the entire engine time to thaw. If you’ve parked outside, and depending on the weather, it could take hours, even days, for a frozen engine to thaw properly. If you can safely move (push or tow, don’t’ drive) the vehicle into a garage or other sheltered location, this will help the engine thaw. Or direct a fan heater onto the front of the radiator to help speed up the thawing process. Whatever you do, though, the important thing to remember is to not drive the vehicle until you’re sure the cooling system has completely thawed.


Once everything has completely thawed, it’s important to pop in to your local ADRAD radiator repair service and get them to flush the entire cooling system and replace the fluid with a good quality coolant/antifreeze at the right ratio mix.

a good quality coolant/antifreeze at the right ratio mix.

Howw to preserve your radiator to prolong it’s life?

When it comes to the health of your vehicle’s radiator, regular maintenance is the best policy for preventing problems developing in the first place. Here are 4 radiator winter maintenance tips to get your vehicle’s cooling system ready for the cold:

1. Check fluid levels:

Make it a habit to regularly check the fluid levels in the cooling system. If it’s necessary to add fluid, ask your radiator repair agent for professional advice on the right mix of coolant/antifreeze to water.

2. Flush:

Over time, dirt and contaminants will build up in the cooling system, restricting the flow of the coolant/antifreeze. The fluid can also become acidic and lose its effectiveness if not refreshed periodically. Again, your ADRAD radiator specialist can provide you with expert guidance on when to flush.

3. Check radiator caps and hoses:

Look for cracks or other damage on the bottom of the caps, and replace any damaged caps immediately. Make it a habit to also replace caps whenever you flush your vehicle’s radiator. Regularly inspect all hoses that lead to and from the radiator for cracks that may result in coolant/antifreeze leaks. Ask your ADRAD radiator repair specialist for advice about when to replace hoses – it might be a good idea to do so every three or four years as they can become dry and brittle over time, which could make them prone to bursting.

4. Check the radiator tank:

Visually inspect the radiator tank and the reservoir tank every few months. Often, cracks start out as very small pinholes or punctures that can be easily repaired. If you leave them and they get too big, you may end up having to replace the radiator entirely.

Call 0800 Radiators (0800 723 427)

If you didn’t get around to scheduling a radiator service before winter arrived, it’s not too late!

Contact any one of ADRAD’s nationwide network of radiator specialists and get them to give your vehicle’s radiator and cooling system the once over so you can confidently make it through the winter months hassle-free.

If you’re having any radiator issues, be sure to contact ADRAD’s radiator repair service immediately on 0800 723 427 for help to avoid bigger, more expensive problems developing.