Some Volvo S80 owners report experiencing a high-pitched whistling noise, which may be attributed to issues with a cracked breather box and the PCV system. This noise is often caused by intake manifold vacuum in the crankcase, pulling air past the crank seals due to PCV system problems. Owners have noted that pressing the accelerator can temporarily stop the noise, suggesting a cracked breather box. Additionally, if the noise disappears when the oil filler cap is opened while the engine is running, it likely indicates a PCV issue that requires attention. A cracked breather box can lead to squealing noises and oil pressure problems, making its replacement the recommended repair, especially for older vehicles with higher mileage.

Some Volvo S80 owners report experiencing gas tank leaks due to faulty seals between the pump and the tank, which can pose significant hazards and lead to fuel wastage. Repairing such leaks can be costly, with estimates around $1900. Additionally, there have been instances of recalls related to coolant seal wear and tear that may also contribute to leaks in certain Volvo S80 models. It is crucial for owners to address these gas tank leaks promptly to prevent serious risks, including fire hazards and environmental damage. After completing any recall repairs for gas tank issues, it is recommended that owners monitor their vehicles for signs of recurring leaks and maintain regular maintenance to ensure ongoing safety and performance.