What should I do if my Highlander's engine is making a loud knocking noise?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

medium

Difficulty

high

Severity

4 min read

628 words

⚠️ Safety Warning

This issue requires immediate attention. If you are not experienced with automotive repairs, consult a professional mechanic. Working on critical systems can be dangerous.

Problem Statement

Learn how to diagnose and repair loud knocking noises in the engine of your Toyota Highlander from 2020 to present. Follow our detailed steps and check for common causes.

Affected Component

engine

Symptoms

•A loud knocking noise coming from the engine compartment.
•Noise may vary with engine speed (increases with RPM).
•Potential loss of power or performance.
•Possible check engine light illumination.

Diagnostic Steps

1
Check Engine Oil Level and Condition
2
Scan for Diagnostic Trouble Codes (DTCs)
3
Listen for Knocking Location
4
Inspect Timing Components
5
Check for Fuel Quality

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•Engine oil dipstick
•Oil catch pan
•Torque wrench
•Socket set
•Wrenches
•Screwdrivers
•Engine stethoscope (optional)
•OBD-II scanner

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Solution

Problem Diagnosis: Loud Knocking Noise in Toyota Highlander (2020-present)

Possible Causes

Low Engine Oil Level: Insufficient lubrication can cause knocking.
Oil Sludge Build-Up: Old or contaminated oil can lead to engine knocking.
Knocking Rods: Failure of the connecting rods or bearings may produce a knocking sound.
Piston Slap: Worn piston rings can cause noise during operation.
Timing Chain/Belt Issues: If the timing components are loose or worn, they may produce noise.
Fuel Quality: Low-quality fuel can cause engine knocking (pinging).

Tools Required

Engine oil dipstick
Oil catch pan
Torque wrench
Socket set
Wrenches
Screwdrivers
Engine stethoscope (optional)
OBD-II scanner

Repair Instructions

If Low Oil Level or Condition is the Issue:

Step 1: Add the correct type of engine oil (refer to owner’s manual).
Step 2: If oil is contaminated, perform an oil change:
- Drain old oil using an oil catch pan.
- Replace the oil filter.
- Refill with new oil.

If Engine Knock is Confirmed from Rods or Pistons:

Step 1: Prepare the vehicle by disconnecting the battery and removing any necessary components to access the engine.
Step 2: Remove the oil pan to inspect the connecting rods and bearings.
Step 3: If the bearings are worn or damaged, replace them. This may require replacing the connecting rods as well.
Step 4: Reassemble the engine, ensuring all bolts are torqued to specifications.

If Timing Components are Worn:

Step 1: Replace the timing belt/chain and tensioner according to the service manual specifications.
Step 2: Reassemble the components and ensure proper timing alignment.

If Fuel Quality is the Cause:

Step 1: Fill the gas tank with high-octane fuel.
Step 2: Add a fuel system cleaner to help clean out any deposits.

Final Checks

Start the engine and check for any residual knocking noises.
Monitor performance and ensure no DTCs appear after repairs.
If the knocking persists, further investigation may be required, possibly involving a professional assessment.

Conclusion

Engine knocking can be indicative of serious issues. If basic checks and repairs do not resolve the problem, consider seeking professional assistance to avoid extensive engine damage.