Checking For Loss Of Pressure

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WARNING: Engine can turn without control (the crankshaft can turn because of the pressure in the cylinder).

Danger of crushing (injury)
Tools can become jammed (material damage)

→ 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.

Set the piston position (ignition TDC) and connect test tools.
1. 1.1. Connect the dead-center position gauge -2- . To do this, screw the adapter -3- into the spark plug thread by hand and tighten hand-tight.
  
  Fig 1: Checking Piston Position On 997 II
  Courtesy of PORSCHE CARS NORTH AMERICA, INC.
2. 1.2. Turn the crankshaft clockwise at the vibration damper -8- as far as the TDC marking of cylinder 1 using turning device 9773 -7- .
3. 1.3. Determine the piston position (ignition TDC) of the cylinder to be checked using the dead-centre position gauge.
4. 1.3.1. Piston position of the cylinder to be checked is correct:
  Continue with Step 1.4 (Fix vibration damper in place).
5. 1.3.2. Piston position of the cylinder to be checked is incorrect:
  Continue to turn the crankshaft 360° clockwise at the vibration damper using turning device 9773 -7- .
6. 1.4. Fix vibration damper in place.
  Fix the crankshaft in place above the staking bore on the vibration damper using a locating pin 9595/1 -9- .
7. 1.5. Remove the dead-centre position gauge.
  
  Fig 2: Adjusting TDC Position Marking
  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).
Set the pressure loss tester.
1. 2.1. Connect the test hose -5- to the pressure loss tester -1- .
2. 2.2. Connect the pressure loss tester to the compressed air.
3. 2.3. Pull and open the pressure-regulating valve -4- until the pointer on the pressure loss tester shows 23 %.
4. 2.4. Lock the pressure-regulating valve by pressing it.
  
  Fig 3: Setting Pressure Loss Tester
  Courtesy of PORSCHE CARS NORTH AMERICA, INC.
Connect the pressure loss tester.
1. 3.1. Check that the adapter -3- is seated securely in the spark plug thread.
2. 3.2. Connect the adapter to the test hose -5- .
3. 3.3. Connect the pressure hose -6- to the pressure loss tester -1- .
  
  Fig 4: Connecting Pressure Loss Tester
  Courtesy of PORSCHE CARS NORTH AMERICA, INC.
Check the pressure loss.
1. 4.1. The pointer on the pressure gauge must move within the green area (0-25 %).
  If there is a loss in pressure of more than 25 %, the pressure loss is no longer acceptable and the source of the problem must be found.
2. 4.2. Pressure loss within tolerance range:
3. 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
4. 4.3. Pressure loss not within tolerance range:
5. 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)
6. 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