Audi A8 Quattro Turbocharger Intercooler Tube Replacement Cost

Vehicles with turbocharged induction engines have the option to cool the air being compressed by the turbocharger, and this is done by diverting compressed, filtered inlet air through an intercooler before it is pushed into the intake manifold. The cooler temperatures provided by the intercooler allow the engine to use more fuel per combustion event, making more power on demand. The intercooler is fed by intercooler piping, which also carries air from the intercooler to the intake manifold. Typically, an intercooler tube will be used as the final stage of delivery for the air as it moves to the intake manifold. This is because the tube may need to be flexible or form-fitted, and is typically non-metallic.

As the final stage of boost pressure delivery from the turbocharger to the intake manifold, the intercooler tube should deliver relatively cool air from the intercooler to the intake manifold via the throttle body. Since this tube is not under high heat and must route through other components to arrive at the throttle body, it is typically plastic or a rubber composite material, and will likely be molded to fit directly between components yet prevent limiting airflow. This is also commonly the mounting location for the boost pressure sensor.

Underboost issues are the only issue to consider when the intercooler tube cracks or becomes disconnected. Boost leaks occur in these situations, and the intended amount of compressed air will not arrive at the engine. There may also be an issue with the engine running a rich air to fuel ratio, and the check engine light will illuminate to denote these errors. Lastly, low engine power may be noticed, depending on the size of the leak.

Fuel mileage and engine power may suffer due to a cracked intercooler tube, and the engine may be able to suck in unfiltered and unmetered air. This may lead to adverse running conditions due to debris in the intake and engine. Like any other time the check engine light is on, this issue should not be ignored. Lastly, for transverse mounted four cylinder engines, the intercooler tube may contact and damage the radiator cooling fan if it becomes dislodged.

These tubes are most commonly broken due to mishandling during service and impact damage from collisions. Since the tubes are typically made of plastic or rubber composite materials, they are likely to degrade over time as well. These factors considered, the intercooler tube should last the life of the vehicle, but failure would be most expected late in the vehicle's service life and after a collision.

Diagnosing a failed intercooler tube, as well as any boost leak, requires testing the boost piping from the turbocharger to the intake manifold. The means the system must be disconnected from both, plugged at one end, and pressurized at the other like a leak-down test. Otherwise, fractures or other damage to the intercooler tube and intercooler tube seals are noticed upon physical inspection.

Replacing the intercooler tube requires it be detached from the throttle body and intercooler piping or intercooler. This may be a tedious task, but for longitudinal engines it should be quick and easy. In some vehicles, the radiator fans may need to be removed to extract the intercooler tube.

RepairPal recommends the entire turbocharger system is pressure tested before any portion is declared faulty. If there is no leak evident in the intercooler and intercooler piping, replacing parts is not a good way to find a leak. Remember, there are many locations on a turbocharged engine that can cause a boost leak.

Even a failed turbocharger can mimic conditions caused by a failed intercooler tube, and the tube is one of the least likely components to fail in the turbocharging system. Also, anytime an underboost situation exists, it is important to test the boost pressure sensor to ensure it is functioning properly.

Anyone can diagnose and replace the intercooler tube. Physical inspection is needed, so the intercooler tube should be removed for inspection, but every component that carries boost pressure from the turbocharger to the throttle body connections should be tested. The tool to test these pipes and the intercooler can be purchased or made fairly cheaply. If a leak cannot be found, have a professional diagnose the issue.