2017-2019 Porsche 718 Boxster & Cayman Intercooler: Heat Soak, Leaks, and Replacement Guide

Vehicle Fitment and Key Information

This guide applies to all 2017, 2018, and 2019 Porsche 718 Boxster and Porsche 718 Cayman models equipped with the 2.0L or 2.5L 4-cylinder turbocharged engines. This includes Base, S, and GTS variants within this model year range. The primary function of the factory intercooler is sufficient for daily driving, but its main limitation is a susceptibility to heat soak during aggressive driving or in hot climates.

Known Issues and Performance Limitations

Engine Heat Soak

The most discussed issue with the stock 718 intercooler is not outright failure, but performance degradation due to heat soak. Heat soak occurs when the intercooler absorbs more heat from the engine bay and the compressed air than it can dissipate. When this happens, the intake air temperature rises, and the Engine Control Unit (ECU) protects the engine by reducing ignition timing and turbo boost. The driver experiences this as a noticeable loss of power or a sluggish throttle response, especially after repeated hard accelerations or when driving in stop-and-go traffic on a hot day. While this is a limitation of the OEM design, it is not a defect. Many owners who track their cars or have tuned engines choose to install larger, more efficient aftermarket intercoolers to combat this effect.

Symptoms of a Failing Intercooler

A failing intercooler typically develops a leak in its core or at the connections where the hoses attach. This allows pressurized air from the turbo to escape before it reaches the engine, leading to several distinct symptoms.

• Loss of Power and Acceleration: The most common symptom is a significant drop in engine power. The car will feel sluggish, and the turbocharger's kick will be noticeably weaker because the required boost pressure is not reaching the engine.
• Audible Hissing or Whistling: A leak in the intercooler or its hoses will often create a hissing or whistling sound from the engine bay that gets louder with engine RPM and turbo boost.
• Check Engine Light (CEL): A significant boost leak will likely trigger a Check Engine Light. The most common trouble code is P0299 (Turbocharger/Supercharger Underboost Condition), which is set when the engine's computer detects that the actual boost pressure is lower than the target pressure.
• Increased Fuel Consumption: With less air reaching the cylinders, the air-fuel mixture can become rich, leading to inefficient combustion and a noticeable decrease in fuel economy.
• Black Smoke from Exhaust: In some cases, a very rich fuel mixture caused by a major boost leak can result in black smoke from the exhaust, which is unburned fuel.

Buying a Used Intercooler: What to Check

A used OEM intercooler can be a cost-effective replacement, but a thorough inspection is essential to ensure you are getting a good part. The 718 intercooler is an air-to-water unit, which adds complexity compared to more common air-to-air coolers.

1. Inspect the Core and Fins: Carefully examine the cooling fins on the front and back of the intercooler. A few bent fins are cosmetic and acceptable, but large areas of crushed or damaged fins will restrict airflow and reduce cooling efficiency. Reject any unit with major physical damage.
2. Check for Cracks and Leaks: The end tanks are often made of plastic crimped to the aluminum core. Inspect these areas closely for any hairline cracks, especially around the inlet and outlet ports. Look for white, chalky residue, which can indicate a past coolant leak.
3. Examine Hose Connections: Ensure the inlet and outlet ports are perfectly round and free of cracks or damage. A damaged port will not seal properly with the boost hoses, leading to leaks.
4. Check for Oil Contamination: A light film of oil inside the intercooler is normal, as the PCV (Positive Crankcase Ventilation) system can route some oil vapor into the intake tract. However, a large amount of pooled oil inside suggests a failing turbocharger, and the intercooler may be heavily contaminated or clogged.
5. Verify Mounting Points: Check that all mounting tabs and brackets are intact and not cracked or broken. Damaged mounting points can cause vibrations that lead to future leaks.

Official Recalls and Technical Service Bulletins (TSBs)

As of this writing, there are no specific recalls or TSBs for intercooler failure on the 2017-2019 Porsche 718 models. However, there is one important safety recall for these vehicles.

• NHTSA Recall #19V113000 (Porsche Campaign #AKA3): This recall affects approximately 14,400 model-year 2017-2019 718 Boxster and Cayman vehicles. The issue is that a crossmember for the luggage compartment bracket may detach during a crash, potentially causing a fuel leak and increasing the risk of a fire. The fix involves dealers securing the crossmember with additional rivets, free of charge.

Replacement Overview

Replacing the intercooler on a 718 Boxster or Cayman is a moderately difficult job that requires accessing the top of the engine. This involves removing several trim pieces from the rear trunk and inside the cabin behind the seats.

General Steps:

1. Remove the rear trunk liner and plastic trim panels covering the top of the engine bay.
2. From inside the cabin, remove the trim panels behind the seats and the upper carpeted engine cover to gain full access.
3. Once the engine is exposed, the intercooler is visible on top. Disconnect the air inlet and outlet hoses, which are typically held by spring clamps.
4. Disconnect any sensors and vacuum lines attached to the intercooler assembly.
5. Unbolt the intercooler from its mounting brackets. There may be a hidden bolt that requires a swivel socket and extension to reach.
6. Carefully lift the old intercooler out of the engine bay.
7. Installation is the reverse of removal. Ensure all hose clamps are tight and that all electrical and vacuum lines are reconnected securely.

Cost Comparison

The cost to replace a 718 intercooler can vary significantly depending on the type of part used.

Frequently Asked Questions (FAQ)