Coolant hoses are built to last. Typically made from durable rubber, coolant hoses can last for several years before they show signs of wear. However, constant exposure to high temperatures inside the engine can speed up the deterioration process for some. To prevent coolant leaks and other major issues in the cooling system, it’s best to inspect your car’s coolant hoses every 3,000 miles or so.
How To Inspect Your Coolant Hoses
Here are some helpful tips on how to inspect your coolant hoses:
Let Your Engine Warm
It’s best to inspect your hoses when your engine is still warm. That way, you can easily find any swollen or ballooning parts on the hose. You can also look for small, damp spots at the hose ends, where coolant might have leaked.
Dealing with a hot engine is dangerous, so be extra careful. Wear protective gear like safety goggles and gloves, and wear thick clothing that covers your arms.
Perform a Visual Inspection
The photos below show one hose that is about to burst and one that already has.
Perform a Squeeze Test
Gently squeeze the radiator hoses and check for any hard parts. A coolant hose that’s in good condition should feel firm but not too hard or too soft. It should retain its shape and spring back to its original form after squeezing. If it feels hard, soft, or spongy at any point, the entire hose should be replaced.
Look for Cracks
Visually inspect each hose for any cracks or fraying. Even the tiniest crack can lead to a big leak, so be sure to replace the hose if you find any damage. You can also check if any hoses are touching sharp edges or hot engine parts, which can cause them to wear faster.
Check the Clamps
Clamps secure coolant hoses to the radiator and engine. Over time, however, they can fail and lead to coolant leaks. When inspecting your hoses, take the time to also check their clamps for any signs of damage.
What Are the Common Types of Hose Failure?
To say that your vehicle’s coolant hoses go through a lot might be an understatement. They’re constantly exposed to high temperatures and harsh chemicals, so it’s only natural that they’ll wear over time. Here are the common types of hose failure:
Electrochemical Degradation
Electrochemical degradation, or ECD for short, isn’t easy to detect. It attacks the coolant line from the inside, causing tiny cracks that can eventually cause the hose to rupture.
What Happens to the Hose?
Check the first two inches from the hose ends, where ECD damage can usually be found. Hoses weakened by ECD also have softer ends and will feel as if they have gaps inside when squeezed.
What Is the Cause?
Your cooling system consists of parts that are all made from different kinds of metal. These various metals generate an electrical charge that is then carried by the coolant. This electric charge can cause small cracks in the hose.
How Do I Fix It?
You’ll have to replace the damaged hose with a new one.
Leakage
If you find a pool of coolant under your parked car, there’s a big chance you’re dealing with a leaking coolant hose. This can lead to an overheating engine and drips of coolant leaking into the engine bay.
What Happens to the Hose?
You’ll find coolant marks on or around the clamps, connectors, or on the hose itself.
What Is the Cause?
Coolant leakage is typically caused by worn hoses, deteriorated connectors, and insufficient clamp torque.
How Do I Fix It?
You can try retightening the clamps or switching to constant-tension clamps. If you’re dealing with worn hoses, you’ll have to replace them.
Heat Damage
Coolant hoses are specifically designed to hold up against high temperatures, but they don’t last forever. They can still wear over time and suffer from heat damage.
What Happens to the Hose?
Hoses damaged by extreme heat will feel hard and look glossy with a cracked outer surface. If the hose is damaged inside, it will also look swollen.
What Is the Cause?
Constant exposure to engine heat, sudden temperature spikes, and low coolant levels can lead to heat damage.
How Do I Fix It?
You’ll have to replace the entire hose.
Ozone Damage
Over the years, pollution has gradually gotten worse, causing ozone levels to rise. This can damage your vehicle just as much as it hurts the environment.
What Happens to the Hose?
Coolant hoses suffering from ozone damage will have tiny, parallel cracks on their outer surface.
What Is the Cause?
Higher ozone levels damage the bonds in certain rubber compounds, causing the hose to deteriorate and crack. This allows dirt and other debris to enter the system.
How Do I Fix It?
Replace your cracked hose with a new one made from ethylene propylene diene monomer (EPDM). It’s a type of synthetic rubber that can withstand extreme conditions and last longer than natural rubber.
Abrasion Damage
Some engines have gotten smaller. They’ve become so compact that coolant hoses sometimes rub against other hot and moving engine parts.
What Happens to the Hose?
You’ll find rub marks, holes, and cracks on the hose’s outer surface.
What Is the Cause?
Abrasion damage is caused by constant friction between parts of the engine and the coolant hose.
How Do I Fix It?
You can try rerouting the hose or installing a protective hose cover, sleep, or wrap. If the hose is badly damaged, however, you’ll have to replace it first.
Oil Contamination
Coolant hoses are typically made of rubber, which can react negatively when exposed to oil and other petroleum-based products. This is why oil contamination is another common type of hose failure.
Pro Tips are nuggets of information direct from ASE-certified automobile technicians working with CarParts.com, which may include unique, personal insights based on their years of experience working in the automotive industry. These can help you make more informed decisions about your car.
Pro Tip: An oil leak that keeps a hose damp with engine oil will cause it to swell and eventually burst.
What Happens to the Hose?
Coolant hoses will feel soft or spongy when squeezed. Oil can also cause coolant hoses to bulge and swell.
What Is the Cause?
Oil and other petroleum-based products attack and weaken rubber compounds, causing the coolant hose to soften. Internal damage can happen when the coolant is contaminated with oil, while external damage can occur when a failed head gasket causes oil to leak into the cooling system.
How Do I Fix It?
Replace the degraded hose and address the source of the oil leak.
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