How to Check Engine Vacuum Hoses

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Knowing what faulty vacuum hoses look like is an important part of keeping your car in good condition. Many of these hoses control your car's idle, emissions components and environmental controls such as your heat. This article will tell you how to check engine vacuum hoses.

Steps

Visual and Hands-On Inspection

1. 1
   Check each hose for bulges and swelling. If a hose feels soft or spongy when you touch it, this can indicate damage caused by your car's oil.

   
   

   • A swollen hose that is cracked and hard is often caused by heat damage. These hoses can be too close to heat sources under the hood or it may be the result of overheating.
   • Bulging hoses can also be caused by electrochemical degradation when there's a coolant leak dripping onto hoses. Sometimes you can feel tiny cracks or weak spots when you squeeze a cool hose near one of the ends.
2. 2
   Examine the hoses for tiny cracks and scratches. Small parallel cracks in the cover of a hose can be ozone damage. Scratches and other irregular injuries to the hoses can be caused by hoses rubbing against a moving part of the engine.

Using a Vacuum Detector

1. 1
   Detach the vacuum hose from a system or accessory of your car, such as the hose from your heater or cruise control.
2. 2
   Attach your vacuum gauge and start your vehicle's engine. Allow your car to idle for a couple of minutes. Your gauge should read between 14 and 18 inches of vacuum.
   • If the reading is low or non-existent, there's a blockage or leak in the vacuum line. Visually check the entire length of the hose for the problem.

   
   

Tips

• Some leaks are not visible during the visual inspection. In these cases, using a vacuum detector in conjunction with a hands-on examination can be useful.
• A hissing or vacuum sound can sometimes be heard if the leak is big enough.
• If you are unable to locate a suspected leak, take your vehicle to a mechanic's shop where there's more sophisticated detecting equipment.

Things You'll Need

• Flashlight
• Vacuum detector (optional)

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