2020 Ford Explorer Knocking Noise? Here's How to Diagnose & Fix It

Overview

A knocking noise from your vehicle is one of the most common—and most unnerving—sounds an owner can hear. It’s a broad symptom that can point to dozens of underlying issues, ranging from a simple loose part to a serious mechanical failure. Based on an analysis of 100 owner discussions, this noise is rarely something you should ignore, but the good news is that it’s often a fixable problem that doesn't always require a massive repair bill.

How It Manifests

Owners describe this noise in a few key ways, and paying attention to when and where you hear it is your first major clue. The most common reports include:

• A rhythmic "knock-knock-knock" that speeds up as you accelerate. This often points to a rotating component like a driveshaft or CV joint.
• A single, heavy "clunk" or "thud" when starting from a stop, shifting gears, or going over bumps. This is frequently linked to suspension or driveline mounts.
• An intermittent rattle or knock that seems to come from under the vehicle or the front end, sometimes changing with road temperature or vehicle load.

In the discussions analyzed, the context of the noise was critical. It appeared when turning, during specific weather (leading some to suspect parts like an oil pan heater coming loose), or only when certain wheel options (like heavier aftermarket wheels) were installed.

The Usual Suspects

Based on repeated fixes and diagnoses from the owner discussions, a few culprits appear much more often than others. Think of this as your shortlist.

1. Driveshaft/U-Joints: This was the single most cited cause for a rhythmic knocking, especially in rear-wheel or four-wheel-drive vehicles. A worn universal joint on the driveshaft can create a very distinct knocking sound that correlates directly with wheel speed.
2. Suspension Components: Worn control arm bushings, sway bar end links, or ball joints can cause clunking noises, particularly when going over bumps or turning. Issues with air ride suspensions were specifically mentioned, where a failing air strut or compressor can create knocking.
3. Exhaust/Heat Shields: A loose exhaust system or a heat shield that has come unbolted can rattle and knock against the underbody or firewall, mimicking a more serious sound.
4. Loose Underbody Components: This includes the aforementioned oil pan heater, skid plates, or even the spare tire. These often cause an inconsistent, baffling knock.
5. Engine-Related Knocks: While less frequently the direct cause in these discussions, it’s important to note that a deep, internal knocking from the engine itself (like rod knock) is a severe issue requiring immediate attention.

Finding the Problem

Pinpointing a knock requires a systematic approach. You can do a lot of this yourself safely.

1. Listen and Note: Be a detective. Does it happen when cold or hot? Only when turning left? Only over bumps? Write it down.
2. The Visual and Physical Inspection:
   • Shake the Driveshaft: With the vehicle safely raised and supported (transmission in Park, wheels chocked), try to rotate and shake the driveshaft. Any noticeable clunk or play at the U-joints is a telltale sign.
   • Check the Exhaust: Gently push and pull on the exhaust pipes. Listen for rattling and look for any components touching the body.
   • Inspect Suspension: Push down firmly on each corner of the vehicle to get it bouncing. Listen for knocks. Visually inspect rubber bushings for cracks and tears.
3. The Helper Method: Have a friend slowly drive the car back and forth in a quiet, safe area while you walk alongside (or even crouch nearby) to try and isolate the area the noise is coming from.
4. When to Get Professional Help: If your inspection points towards the engine internals, transmission, or if the knock is severe and worsening quickly, it’s time for a pro. A mechanic can use a stethoscope or put the vehicle on a lift to safely replicate the noise under load.

How to Fix It

Here are the solutions, ranked by how often they resolved the issue in the discussions, starting with the simplest and most affordable.

1. Tighten Everything Down (First Step!): Before buying any parts, get under the car with a wrench and socket set. Methodically check and tighten:
   • Exhaust hangers and heat shields
   • Skid plates and underbody panels
   • Spare tire and jack
   • Strut tower nuts under the hood This $0 fix resolved a surprising number of reported knocks.
2. Replace Worn Driveshaft U-Joints or CV Axles: If you found play in the driveshaft, replacing the U-joints (or the entire driveshaft assembly) is the fix. For front-wheel drive knocks when turning, a worn CV joint on an axle is likely. This is a very common and confirmed fix.
3. Replace Suspension Bushings or Links: Worn control arm bushings or sway bar end links are common culprits for "clunk over bump" noises. Replacing these components restores tightness to the suspension.
4. Address Air Ride System Faults: For vehicles equipped with air ride suspensions, a knocking can indicate a failing air strut, a leaking bag, or a faulty compressor. Diagnosis with a specialized scan tool is often needed here.
5. Engine or Transmission Mounts: Worn mounts can allow the engine/transmission to shift excessively, causing a heavy knock during acceleration or gear changes. Inspection often requires lifting the vehicle to see the mounts clearly.

What to Expect to Pay

Costs vary wildly based on the cause and your choice to DIY.

• DIY (Do-It-Yourself):

  • Tightening Loose Parts: $0 - $20 for your time and maybe a new bolt.
  • Sway Bar End Links: $30 - $100 for parts. Generally a 1-2 hour job for a novice.
  • Driveshaft U-Joints: $50 - $150 for parts. Requires special tools (snap ring pliers, press) and mechanical confidence.
  • Control Arm with Bushing: $100 - $300 per side for parts. Requires an alignment afterward.

• Professional Repair (Parts & Labor):

  • Exhaust/Heat Shield Securing: $50 - $150.
  • Sway Bar End Link Replacement: $150 - $300.
  • Driveshaft U-Joint/CV Axle Replacement: $300 - $700.
  • Control Arm Replacement: $400 - $800 per side.
  • Air Suspension Strut Replacement: $1,000 - $2,500+ per corner, depending on the vehicle.

Avoiding Future Issues

Preventing a knock is mostly about proactive maintenance and paying attention.

• Listen to Your Car: Address new sounds immediately. A small rattle can be a loose part that, if ignored, can lead to a larger failure.
• Regular Underbody Checks: When you rotate your tires or get an oil change, take a moment to visually scan for anything hanging loose or looking damaged.
• Follow Suspension Service Intervals: While not always in the manual, having your suspension (bushings, ball joints, tie rods) inspected annually or with brake service can catch wear early.
• Be Mindful of Modifications: As noted in discussions, changing wheel options to much heavier setups can put extra stress on suspension and driveline components, accelerating wear.

Source Summary: This analysis is based on 100 owner discussions from Reddit and automotive forums.