Drivetrain Issues:
* Worn or unbalanced driveshaft: This is a common culprit. A damaged or unbalanced driveshaft will cause vibrations, especially under acceleration.
* U-joints: These connect the driveshaft sections. Worn U-joints will produce a characteristic clunking or vibrating sound, especially when accelerating or turning.
* Transmission problems: Issues within the transmission itself, such as worn gears or internal components, can lead to vibrations during acceleration. This could be a more serious and expensive problem.
* Differential problems: Problems with the differential (the part that distributes power to the wheels) can also cause vibrations, particularly under acceleration. Worn bearings or gears are possibilities.
* Wheel bearings: While these often cause a humming noise at higher speeds, a severely damaged wheel bearing *can* contribute to vibration under acceleration, especially if it's on a drive wheel.
Engine Issues (Less likely to be solely vibration at acceleration):
* Engine mounts: Worn engine mounts allow excessive engine movement, leading to vibrations that can be felt throughout the vehicle. However, this often manifests as a general vibration, not necessarily just during acceleration.
* Unbalanced engine components: Though less common, an internal engine imbalance (e.g., from a damaged flywheel) could cause vibrations. This is usually accompanied by other symptoms like rough running.
Other Potential Causes:
* Tires: Unbalanced tires or tires with uneven wear are a very common cause of vibration. This will usually be felt at higher speeds but *could* be worsened by acceleration. Check tire pressure as well.
* Wheels: Bent or damaged wheels can also cause vibrations.
* Brakes: Though less likely, warped brake rotors could cause vibrations during acceleration, but this usually presents as a vibration during braking as well.
Troubleshooting Steps:
1. Check tire pressure and condition: This is the easiest and cheapest thing to check first.
2. Inspect tires and wheels: Look for any obvious damage, uneven wear, or bent components.
3. Listen carefully to the vibration: Is it a high-pitched whine, a low-frequency rumble, or a clunking sound? This can give clues about the source.
4. Check under the vehicle: Look for any obvious signs of damage to the driveshaft, U-joints, or other drivetrain components. (Safety first - make sure the vehicle is cool and on a level surface before doing this).
Professional Help:
Because several serious mechanical issues can cause this symptom, it's highly recommended to take your 2008 Ford Explorer to a qualified mechanic for diagnosis and repair. Attempting DIY repairs on drivetrain components without experience can be dangerous. They'll have the tools and expertise to properly pinpoint the source of the vibration.
