1. Home
  2. Articles
  3. What Causes Hoses to Leak?

What Causes Hoses to Leak?

leaking engine hose

While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include:

  • Engine oil
  • Transmission fluid
  • Coolant
  • Power steering fluid
  • Brake fluid
  • Washer fluid

All of these fluids must be transported from one place to another in order to do their job. While some fluids run primarily within the engine or another component (oil, for instance, or transmission fluid), others don’t. Consider engine coolant – it’s stored in your radiator and overflow tank/reservoir, but must move from there to the engine and then back again. Power steering fluid is another prime example – it must be moved from the power steering fluid reservoir at the pump, into the rack and then recirculated once more. Moving fluid from one area to another requires hoses, and hoses are prone to wear and tear. They’ll eventually decay and need to be replaced.

Hose leaks and their causes

Hose leaks are caused by a number of different factors. The primary one is heat. Hoses in the engine bay are exposed to high temperatures on a regular basis, both inside and out. For example, coolant hoses must deal with heat from the engine, as well as heat from the coolant itself.

While very resilient, rubber (the primary material for all hoses) does degrade. Exposure to high temperatures causes the rubber to dry out. As it dries, it becomes brittle. If you’ve ever squeezed a worn out hose, you’ve felt the “crunch” of dry rubber. Brittle rubber doesn’t do well with pressure or heat, and will eventually rip, tear or at least decay to the point that you have a pinhole leak with fluid spraying out.

Another cause is contact with a hot or sharp surface. The wrong size hose, or one that has been kinked into an incorrect position, may contact sharp or very hot surfaces in the engine bay. Sharp areas will wear away at the hose, essentially cutting through the rubber (fueled by vibrations from a running engine). Hot surfaces can melt rubber.

Finally, when you combine pressure with heat exposure, you have a recipe for leaking. Most of the hoses in your engine carry pressurized fluid, including hot coolant, pressurized power steering fluid, and pressurized brake fluid. After all, hydraulic systems work because fluid is pressurized. That pressure builds within the hose, and if a weak spot develops, it will punch through, creating a leak.

Hose leaks may have nothing to do with the hoses at all. If the leak is located at an end, the problem may actually be the clamp securing the hose to the nipple or inlet. A loose clamp can cause a very serious leak without any damage necessary to the hose.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

Veteran and Military Driver Laws and Benefits in New Mexico
The state of New Mexico offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch...
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...
P2422 OBD-II Trouble Code: Evaporative Emissions Control System (EVAP) Vent Valve Stuck Closed
Diagnostic Trouble Code (DTC): P2422 P2422 code definition Evaporative Emissions Control System (EVAP)...

Related questions

Q: Is There a Difference Between a Car's Upper and Lower Radiator Hoses?

The difference between the upper and lower radiator hoses is where on the engine they are used. They are made of the same material (EPDM), so they both meet the requirements of thermal stability, pressurization, and life expectancy. The upper...

Q: Fans aren't spinning

If the fans were working before the radiator replacement, it's possible a temperature sensor and/or wire were left disconnected or damaged. The O2 sensor should not be unplugged but may not be the cause of the fans not working. I'd...

Q: Water leaking from car

If the water you found leaking out by the passenger is clear, then it is completely normal. The water comes from condensation that leaks from the air conditioning system. If the leak has any tinge of green from coolant then...