Preliminary Work

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Unscrew all spark plugs. → REMOVING SPARK PLUGS
Position cylinder to be tested to ignition TDC and remove tool (dead center finder).
1. 2.1. The dead center finder or "cylinder pipe" consists of a glass tube (inspection glass) with a piston -1- , hose and a rubber cone -2- .
  
  Fig 1: Identifying Cylinder Dead Centre Finder
  Courtesy of PORSCHE CARS NORTH AMERICA, INC.
2. 2.2. The rubber cone is pressed onto the spark plug hole. The inspection glass is either held by a helper → Tool setup for dead center finder or is secured vertically in a clearly visible position with a magnet.
  
  Fig 2: Installing Dead Centre Finder Tool
  Courtesy of PORSCHE CARS NORTH AMERICA, INC.
3. 2.3. If the engine is now turned in direction of rotation on the crankshaft, the piston in the inspection glass is pressed up in the compression cycle → Piston up in order to go back down immediately upon reaching the TDC. The piston in the inspection glass stays down in overlapping TDC → Piston down .
  
  Fig 3: Identifying Piston Up Position
  Courtesy of PORSCHE CARS NORTH AMERICA, INC.
  
  Fig 4: Identifying Piston Down Position
  Courtesy of PORSCHE CARS NORTH AMERICA, INC.