How to Inspect Car Belts and Hoses


Keeping a car running smoothly and reliably for the long term requires routine maintenance. While cars have, in many ways, become sophisticated computers on wheels, there are still some basic manual tasks that can make a significant difference, like regular inspections in front of your house.

By inspecting the body, tires and under the hood you can spot developing problems before they cause costly breakdowns and inconvenience.

For example, a belt or hose failure can cause the engine to overheat, as well as loss of power steering or loss of the electrical charging system. If a hose leaks coolant or the belt that turns the water pump breaks, the cooling system will not work. If the engine overheats, it can suffer serious internal damage that will require expensive repairs and can ruin your summer vacation.

Overheating can happen at any time, but it usually happens in the summer. Underhood temperatures are much higher and the heat can trigger or accelerate the deterioration of rubber compounds.

Here’s what to look for when inspecting accessory hoses and belts, and how to do the inspection yourself.

Cooling and heating hoses

Hoses are the weakest structural component of the cooling system. They are made of flexible rubber compounds to absorb vibrations between the engine and the radiator or, in the case of heater hoses, between the engine and the body firewall. Designed to keep coolant under pressure, hoses are also subject to extreme fluctuations in heat and cold, dirt, oils and sediment. Atmospheric ozone also attacks rubber compounds.

The most damaging cause of hose failure, electrochemical degradation (ECD), is not easy to detect. According to engineers at Gates Corporation, a parts manufacturer, ECD attacks hoses from the inside, causing small cracks. Acids and contaminants in the coolant can weaken the fiber material that reinforces the hose. Eventually, pinholes may appear or the weakened hose may rupture due to heat, pressure, or constant flexing.

Simple, basic maintenance can help prevent cooling hose failures:

  • Check the white coolant recovery tank frequently to make sure the fluid level is correct. Markings on the tank indicate the proper level when the engine is hot or cold. If the fluid level in the tank is low after several fills, there could be a leak. Also check for white, light green, blue, or pink traces of coolant in the engine bay, which are residue from the coolant leak.

  • When the engine is cold, pinch the hoses near the clamps, where ECD most often occurs. Feel them for soft or mushy spots. A hose in good condition should feel firm but flexible.

  • Check for cracks, nicks, bulges (usually while hot); or a collapsed section in the hose and oil contamination; or deterioration near connection points.

  • Look for parallel cracks around bends (caused by ozone), a hardened glassy surface (heat damage), or abrasive damage (hose rubbing).

  • Strip and replace the coolant according to the owner’s manual. Clean coolant is less likely to cause ECD.

  • Never remove the radiator cap when the engine is hot, as the hot coolant will be under pressure. Also, please note that the electric cooling fan can turn on at any time.

The upper radiator hose fails most often, followed by the water pump bypass hose (if the vehicle has one) and the heater outlet hose that connects the engine to the heater core. However, experts recommend replacing all hoses at least every 4 years or when one fails. Always use replacement hoses designed to combat ECD. Trademarks will vary between hose manufacturers. (Gates uses the acronym “ECR” which stands for Electrochemical Corrosion Resistant.) Look for a label that says “EC Type” on the hose or packaging. That’s a standard from the Society of Automotive Engineers that means “electrochemical.” Most vehicles built after 1993 come with ECD resistant hoses.

accessory straps

Many of the elements that attack hoses also attack belts: heat, oil, ozone, and abrasion. Almost every car and truck made today has a single multi-groove serpentine belt that drives the alternator, water pump, power steering pump, and air conditioning compressor. Older vehicles may have separate V-belts that drive the accessories. According to the Car Care Council, after 4 years or 36,000 miles, a V-belt is much more likely to fail, while the critical point for a serpentine belt is 50,000 miles. Every belt should be replaced when it shows signs of excessive wear. But many of the newer composite belts show no signs of wear until failure occurs.

Here are some tips for inspecting belts:

  • Look for cracks, frays, or cracks in the top cover.

  • Look for signs that the belt is slipping sideways. Slippery or slippery belts can slip, overheat or crack.

  • Rotate the serpentine belt looking for signs of delamination, cracks, or missing bits in the grooves at the bottom.

Replacement belts must be identical in length, width and number of grooves to the factory belt. Serpentine belts are usually kept tight with an automatic tensioner. Signs of a belt tension problem are a high-pitched hissing or grinding noise and vibrating noises. If they don’t have the proper tension, the belts will slip and generate heat or won’t be able to turn the accessories.

If in doubt, consult a qualified technician about any cooling problem and always check your owner’s manual for routine maintenance procedures.

Myths about car maintenance

There are many misconceptions when it comes to keeping your car in good working order. On the television show “Consumer 101,” host Jack Rico learns from Consumer Reports expert Jon Linkov the truths about the biggest myths about maintenance.

Consumer Reports is an independent, nonprofit organization that works side by side with consumers to create a fairer, safer, and healthier world. CR does not endorse products or services, and does not accept advertising. Copyright © 2022, Consumer Reports, Inc.

Consumer Reports has no financial relationship with the advertisers on this site. Consumer Reports is an independent, nonprofit organization that works with consumers to create a fair, safe, and healthy world. CR does not endorse products or services and does not accept advertising. Copyright © 2022, Consumer Reports, Inc.

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