Skip the auto shop - Our mechanics make house calls

Q: When Should Engine Hoses be Replaced?

asked by on

When should engine hoses be replaced?

A: Regularly scheduled maintenance of hoses va...

Regularly scheduled maintenance of hoses varies between vehicle manufacturers, but a good rule of thumb is to replace them whenever you have the cooling system serviced (cooling system flushed) or at 100,000 miles.

In the years past, hose technology was such that we could tell when a hose was getting soft and spongy and needed replacement. With better hose materials today, that is no longer the case. The hose interior needs to be checked thoroughly if we are to detect any degradation of the hose itself.

"What makes hoses go bad?", you may ask. This is what happens in your vehicle's cooling system. Vehicles today are highly electrified and electronic. We use a variety of materials in their manufacture. In the engine cooling system alone, we use (or have used) iron, aluminum, brass, tin, steel, and rubber. Using these dissimilar metals and rubber, then add coolant and an electric current, now we have a perfect storm of potential system failure.

We don't purposely add electricity to the cooling system, but it happens anyway because we use the engine block, cylinder heads, and intake manifold as part of the vehicle's electrical circuit. Therefore, as current passes through these engine components, current also passes through the coolant and attacks the interior walls of the hoses, causing the hoses to erode. This process is called electrolytic erosion. This same process causes radiators and heater cores to leak, also, by eating away the solder that holds them together.

How do you know when to flush your cooling system to prevent the ill effects of electrolytic erosion? Here's an old mechanic's trick: take a voltmeter and set it on the DC volts scale. Start the engine and let it idle. Remove the cap from the degas bottle (or radiator) and place the red (positive) lead into the coolant of the engine. Place the black (negative) lead on the negative post of the battery. Look at your voltmeter. If it reads greater than 0.5 volts DC, it's time to flush your cooling system. This small amount of voltage is sufficient enough to eat away the solder in the joints of the radiator and heater core, and weaken your hoses from the inside.

Should you have any other questions or need help servicing the cooling system of your vehicle, consider having it done by a certified mechanic. Being stranded in the middle of nowhere with a broken car is not fun. Been there, done that.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Bottom right radiator hose will not go into new radiator

Get a transmission line disconnect tool or pop the clip out with a small pick tool and reinstall it. The 'jiffy-tite' connectors and manufacturers of radiators will make the adapter fittings different sizes which could be why you are experiencing...

Q: Power steering hose leaking

Hello. The high pressure power steering hose is the most common hose to leak on your vehicle. I have also seen the return line leak at the power steering reservoir from a loose clamp. If the leak cannot be easily...

Q: Gas tank seal from the filler neck hose.

The nozzle I believe your are mentioning is the anti-siphon and roll-over check valve. It does not require a perfect seal to the tank. The rubber filler hose slides over it, sealing in fuel vapors. I hope this helps. Put...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...