Checking Pressure Loss Of Cylinders

The Scope Of Work Described Here Was Carried Out Using The Recommended Tester! 

→ The piston must be exactly at top dead center (TDC) position (secure the crankshaft).

→ Do not touch any belt drive components when building up pressure.

→ Do not insert any tools on the crankshaft belt pulley.

1. Set the piston position (ignition TDC) and connect test tools.
   1. 1.1. Screw in adapter -1-  for M14 spark plug thread and tighten hand-tight. Connect the dead-center position gauge -2-  .
      Fig 1: Checking Piston Position Using Dead-Centre Position Gauge

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
   2. 1.2. Turn the crankshaft clockwise at the vibration damper as far as the TDC marking of cylinder 1 using Turning Device 9773  .
   3. 1.3. Determine the piston position (ignition TDC) of the cylinder to be checked using the dead-center position gauge.
      1. 1.3.1. Piston position of the cylinder to be checked is correct:

         Continue with Step  1.4 (Fix vibration damper in place).

      2. 1.3.2. Piston position of the cylinder to be checked is incorrect (overlap):

         Continue to turn the crankshaft 360° clockwise at the vibration damper using turning device.

   4. 1.4. Fix vibration damper -1-  in place with Locating Pin 9595/1 -4-  .
      Fig 2: Fixing Vibration Damper In Place

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
   5. 1.5. Remove the dead-center position gauge.
2. Set the pressure gauge -1-  .
   1. 2.1. Connect the compressed air hose -2-  to the pressure gauge.
   2. 2.2. Connect the compressed air hose to the compressed air system.
   3. 2.3. Pull and turn the pressure-regulating valve -3-  until the pointer on the pressure loss tester shows 23 % -arrow-  .
   4. 2.4. Lock the pressure-regulating valve. Disconnect compressed air hose.
      Fig 3: Connecting Compressed Air Hose To Pressure Gauge

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.

      Information 

      • Pressure of between 6 and 12 bar is required for carrying out the pressure loss test  .
      • Start the test at cylinder 1 and continue according to firing order (1 - 6 - 2 - 4 - 3 - 5)  .
3. Connect the pressure gauge -1-  to the adapter -3-  .
   1. 3.1. Secure the pressure gauge with tie-wraps -2-  and connect the test hose to the adapter -arrow-  .
   2. 3.2. Connect the compressed air hose to the pressure gauge.
      Fig 4: Connecting Pressure Gauge To Adapter

      Courtesy of PORSCHE CARS NORTH AMERICA, INC.
4. Check the pressure loss.
   1. 4.1. The pointer on the pressure gauge must move within the green area (0-25 %)  .

      A loss in pressure of more than 25 % is no longer acceptable and the source of the problem must be found! 

   2. 4.2. Pressure loss within tolerance range:
      1. 4.2.1. Check the pressure loss on the next cylinder in the same way as for cylinder 1.

         Firing order: 1 - 6 - 2 - 4 - 3 - 5 

   3. 4.3. Pressure loss not within tolerance range:
      1. 4.3.1. Locate the leak by listening for sounds of escaping air.

         The following areas can be checked: 

         Intake manifolds (checking intake valves)

         Exhaust manifolds and exhaust pipes (checking outlet valves)

         Positive crankcase ventilation and oil filler neck (checking piston rings)

         Coolant filler neck and spark plug bore of adjacent cylinder (checking cylinder head gasket)

      2. 4.3.2. Then, continue checking the next cylinder in the same way as for cylinder 1.

         Firing order: 1 - 6 - 2 - 4 - 3 - 5 

5. Remove the turning device from the vibration damper.