Abstract: Test apparatus for the oil cooler from a Volkswagen.RTM. automobile including a support having apertures and studs compatible with the mounting studs and apertures of a Volkswagen.RTM. oil cooler. The support has an air chamber with two ports communicating with the ambient atmosphere located to sealingly engage with the inlet and outlet ports of a Volkswagen.RTM. oil cooler when the oil cooler is mounted on the support. A pressure gauge is connected to the air chamber, and a one-way air entry conduit is also connected to the air chamber. When the oil cooler is installed on the support air under pressure is applied to the air entry conduit which fills the air chamber together with the oil cooler. When the pressure remains constant it indicates that there is no leak in the oil cooler. Conversely, a pressure drop indicates a leak in the oil cooler.