Ford F-150/F-250: Why is My Truck Vibrating?

Engine vibration can be a difficult problem to pinpoint because it tends to feel the same regardless of what's broken. However, there are a few ways to determine what it is that's making an F-150 rattle.

By Marc Carter - November 10, 2014

This article applies to the Ford F-150 (2004-2014) and Ford F-250, F-350, and Super Duty trucks (2005-2014).

Vibration from a massage chair is comforting, but when it’s coming from a truck’s engine, it’s neither soothing nor calming. F-150s and F-250s run so smoothly when brand new, but with age their engines can produce an uncomfortable vibration. Use this step-by-step guide to help isolate what could be causing this issue.

Step 1 - Pull codes with a reader

The best way to tell if there is something wrong with the engine is to hook the engine up to a code reader. The engine’s on-board diagnostics spit out a series of error codes that can disclose what part of the engine is not functioning correctly. A technician can do this, or a code reader can be purchased for less than $100. More expensive readers will say what the code means according to its code database, while others will provide just the code. A local auto store will be able to decipher what that code means. If there are no codes, move on to step two.

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Figure 1. Typical OBD II reader.

Step 2 - Check the motor mounts

The motor mounts are designed to keep the engine in place and from hitting other components under the hood. When the truck accelerates, the engine produces torque that wants to turn the engine, but the motor mounts keep it in place. If the motor mounts break, the engine will shake or vibrate. Engine mounts are located on the side of the engine; determine if they are broken by having a friend rev the engine while it’s in park. If there is excessive movement, then they may need to be replaced.

Figure 2. F-150 motor mounts in bad condition.

Step 3 - Check the spark plugs and plug wires

If the engine mounts are functioning correctly, it is advisable to check the spark plugs and plug wires. If the spark plugs need to be changed, this could cause excessive vibration at idle. Most automakers have a recommended schedule for changing the spark plugs.

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Figure 3. The plug on the left is covered in deposits and will not work well. Also, the gap is too large. Compare it to the new spark plug on the right.

Pro Tip

Diesel engines just need compression to combust fuel, and therefore, have no spark plugs. Instead, they have glow plugs that help the engine start when it's cold. If these go out, a F-250 or F-350 will likely not start in cold conditions.

Step 4 - Check for bad fuel injectors

Fuel injectors play a role in making sure the engine is getting the correct fuel and air mix. Fuel injectors eventually wear out or get clogged, which may mean they will need to be replaced. There are several ways to test them, such as listening for certain clunking sounds from the injector, or taking them off and using various machines to test them. In most cases, if the fuel injectors are dirty it is recommended to have them cleaned, which is much cheaper than replacing them.

  • Figure 4. Injector with damaged rubber o-ring.
  • Figure 5. Injectors should spray in an even cone. When failing, they'll spray in the patterns shown above.

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