Vehicle description: Pickup trucks equipped with diesel engines. The engine driven vacuum pump can allow engine oil into the vacuum hoses due to the absence of an internal check valve. The oil can cause the hose to deteriorate and partially collapse, reducing the vacuum supply to the brake booster.
Dealers will add a vacuum pump check valve to the vacuum pump. In addition, the vacuum hose connected to the vacuum pump will be replaced with a hose that is engine oil resistant.
