2018-2023 McLaren 720S Air Intake: Brackets, Foam, and Failing Turbo Inlets

Symptoms of Air Intake System Failure

Problems within the McLaren 720S air intake system can range from minor noises to issues that pose a direct threat to the engine. It's important to distinguish between the different potential causes.

Symptoms of a Broken Support Bracket

• Rattling or Buzzing Noises: The most common symptom is a rattling sound from the rear of the car, especially over bumps or under acceleration. This is caused by the unsecured airbox vibrating against the chassis or other components.
• Visible Damage: A physical inspection may reveal a cracked or broken bracket, particularly around the bolt holes where stress is concentrated.
• Loose Airbox: You may be able to physically move or wiggle the air filter housing by hand if its mounting bracket is broken.

Symptoms of Critical Intake Component Failure

• Loud Whistling Sound: A distinct whistle from the engine bay, often described as sounding like a Dyson vacuum, is a classic sign of a failing turbo inlet pipe. This happens when the internal components break loose and disrupt airflow.
• Loss of Power: If the turbo inlet pipe collapses or its internal baffles block the airway, the engine will be starved for air, resulting in a noticeable reduction in performance.
• Check Engine Light: A significant leak of unmetered air from a broken turbo inlet or a failed Intake Sound Generator (ISG) can cause the engine to run lean, triggering fault codes and illuminating the check engine light.

Known Issues, TSBs, and Recalls for the 2018-2023 McLaren 720S

While the air filter bracket itself is not a common failure point, the 720S has several well-documented issues in and around the intake system that owners and buyers must be aware of.

Critical Issue: Turbo Inlet Pipe Failure

The factory-installed plastic turbo inlet pipes on the M840T engine have internal silencers and baffles that are prone to breaking loose. Heat cycles, vibration, and increased airflow on tuned cars can cause these internal parts to detach and get sucked into the turbo. This is a widely recognized problem, especially on 2018-2019 models, and many owners proactively replace the plastic factory pipes with more durable silicone or carbon fiber aftermarket units that do not have these internal baffles.

Common Issue: Airbox Foam Disintegration

From the factory, McLaren placed sound-deadening foam inside the air filter housings to reduce intake noise. Over time, this foam breaks down and deteriorates into a sticky, crumbly powder that clogs the air filters. This restricts airflow, hurts performance, and can potentially be ingested by the engine. The standard best practice for mechanics and owners is to remove all of this foam from the airboxes during the first air filter change and thoroughly clean the housing.

Recalls and Technical Service Bulletins (TSBs)

No specific recalls or TSBs (known as Knowledge Articles or 'KA' by McLaren) have been issued for the air filter support bracket. However, other significant safety recalls exist for the 720S:

• NHTSA Recall 20V-231: Affects 2016-2020 models, including the 720S. A foam pad under the fuel tank can trap moisture, leading to corrosion of the tank and a potential fuel leak, which increases the risk of a fire. The remedy involves removing the foam pad and inspecting the fuel tank.
• NHTSA Recall 25V-216: Affects some 2020-2025 models. Brake pipes may have been routed incorrectly into the control module, which could cause a wheel to lock up unexpectedly.

Buying a Used Air Intake Component (Bracket, Housing, or Inlet)

Given the high cost of new McLaren parts, a used OEM component is a smart choice, provided you inspect it carefully. The focus of your inspection should change depending on the part.

Inspecting a Used Support Bracket

• Check for Cracks: Pay close attention to the areas around the mounting holes and at any bends in the bracket. These are the highest stress points.
• Verify Straightness: Lay the bracket on a flat surface to ensure it hasn't been bent or twisted from an impact or improper installation.
• Confirm Part Number: The OEM part number for the left-side bracket is 14A2729CP. Ensure you are buying the correct part for the correct side of the vehicle.

Inspecting a Used Airbox or Turbo Inlet Pipe

• Turbo Inlet Inspection: If buying used OEM turbo inlets, shake them vigorously. If you hear any rattling, the internal baffles are loose, and the part should be considered failed and unsafe to use. Squeeze the pipe to check for cracks or brittleness.
• Airbox Housing Integrity: Check the entire plastic or carbon fiber housing for cracks, especially around the mounting tabs and the cover seal area. Ensure all clips or bolt holes are intact.
• Why Used OEM is a Good Choice: For a simple structural part like a bracket, a verified, undamaged used OEM part offers the exact same fit and durability as a new one for a fraction of the price. For more complex parts like the airbox, it's often the only alternative to a very expensive new part. Aftermarket support for these specific housings and brackets is virtually non-existent.

Cost Comparison

Prices for McLaren parts can be high, making used components an attractive option.

Replacement Overview & Difficulty

Accessing the air filter brackets and housings on a 720S is a moderately involved job that requires some disassembly of the rear of the car.

• Difficulty: 3 out of 5
• Estimated Time: 2-3 hours
• Process: The vehicle must be lifted. The rear wheels and rear fender liners must be removed to gain access to the airboxes, which are located behind them. Once the liners are out, the airbox is held in by several 8mm bolts. The support bracket is then accessible. While the unbolting is straightforward, the access is what makes the job time-consuming.

Frequently Asked Questions (FAQ)