RoadWhen trying to diagnose a mechanical issue with your vehicle, a road test is an essential piece of the puzzle as you go about figuring out exactly what is happening. It is also highly recommended if you are considering the purchase of a used automobile. Taking a customer’s vehicle out on the road is a vital component of the inspection process for a diesel mechanic. There are a number of good reasons to perform a road test and lots of things to keep in mind while you are out there.

Reasons for a Road Test

Performing a road test is a recommended course of action in a few different situations. If you are in the market for a used vehicle, taking your prospective purchase for a test drive may help you to avoid ending up with a lemon that causes you nothing but headaches. For mechanics, a hands-on road test is especially important when troubleshooting a client’s vehicle. It often provides a more reliable explanation of the issues than the complaints of the owner. By taking the vehicle out on the road, you can get a proper feel for potential problems that may be brewing and draw your own conclusions based on firsthand experience.

What to Watch For

Once you have hit the road, it is time to really use your observational skills and use all of your senses to determine the problems plaguing the vehicle in question. Depending on the circumstances, it may be helpful to bring a passenger along for the ride to provide an extra set of eyes and ears to detect any strange sounds or other abnormalities in the operation of the automobile.

Here is what you are looking for during a road test:

  • Regardless of temperature, the engine should feel powerful, perform vigorously, and respond smoothly in every gear, delivering the proper amount of pickup while driving.
  • Brakes should consistently allow for sudden, stable stops without any noise, pulling or fading pedal.
  • When steering the vehicle, make note of any noise or vibration during turns. You should be able to easily control the steering without feeling any looseness, harshness, binding or shimmying in the wheel.
  • To test the clutch and manual transmission, start the engine and set the parking brake before sliding into first gear and gradually releasing the clutch pedal; the engine should begin stalling when the pedal is about half to three-quarters of the way up. A fast, effortless response and easy shifting is what you are hoping for. Automatic transmission should also shift quickly and effortlessly without any hesitation or noise.
  • Likewise, the differential should not produce any unusual sounds or thumping.
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