Water intrusion is one of the few unnoticed killers of the modern automobile. All modern Porsches are even more sensitive to water damage because of their many delicate electrical control units and computers. I remember this all started years ago when Porsche issued a service bulletin on the 924 to re-route and seal the antenna cable because water could travel along this cable and find its way into the central electrics panel inside the vehicle and create havoc with the electrical system.
The main area to watch for water collection in the 986 thru 997’s is the front cowl area. The front cowl area is located just below the base of the windscreen and has water drains on both sides of the battery. There are two front cowl area cavities where debris such as leaves and dirt can collect and in time clog the front cowl drains. When these drains clog water will accumulate in these cavities and at a point migrate into the interior compartment of the vehicle. Water can also enter the brake system vacuum (power) booster unit damaging the booster and causing the brake system to fail usually with the symptom of a stiff brake pedal.
This is a very common problem so we recommend that you regularly open the front hood and inspect for any debris, keeping these areas clean is critical. Additionally, after washing your car or after having driven in the rain, remove the floor mats and put your hand on the carpet in the front and rear passenger areas. The carpet should be dry, if the carpet is damp or wet further inspection for the water source is needed. Keeping water out of the interior compartment and away from all electronic components is critical for the long term health of your car.
All cabriolet models including Boxster’s have two rear cowl areas that are susceptible to water intrusion. This can happen if either of the two drain systems become clogged, the drain hoses are not connected or if either of the two rear cowl area liners are damaged. Liner damage usually happens when the cabriolet top is serviced, if a technician is careless the liner can easily be torn and this will allow the water to no longer follow along the correct path of drainage.
When water from any of these cowl areas leak, it will end up inside the vehicle under one or both of the front seats. Unfortunately the immobilizer (antitheft) control unit is mounted at the lowest point under the driver’s seat and is usually the first component to get wet, in most cases rendering the vehicle undriveable. If the immobilizer control unit is damaged it will be an expensive repair as it will require replacement of the control unit and the specialized knowledge and tools of your Porsche technician because computer (control unit) coding and programming will be required.
Additional causes of water intrusion can include a torn cabriolet top, faulty weather stripping seals, clogged sunroof drains and missing chassis plugs. Other negative aspects of water intrusion inside an automobile can be rust and corrosion.
Tony Callas and Tom Prine