Checking Pressure Loss Of Cylinders

WARNING: This page is about a different variant/trim than selected.

The scope of work described here was carried out using the recommended tester!

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 centre (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.

Screw in the required adapter -1- for the spark plug thread and tighten hand-tight. Connect dead-centre position gauge -2- .

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

Checking piston position using dead-centre position gauge

Turn the crankshaft clockwise at the vibration damper as far as the TDC marking of cylinder 1 using > 9773 - turning device .

Determine the piston position (ignition TDC) of the cylinder to be checked using the dead-centre position gauge.

1.3.1 Piston position of the cylinder to be checked is correct:
Continue with Step 1.4 (Fix vibration damper in place).

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

Continue to turn the crankshaft 3CG° clockwise at the vibration damper.

Fix vibration damper -1- in place with > 9595/1 - locating pin-4- .

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

Disconnecting vibration damper

Remove the dead-centre position gauge.

Set the pressure gauge -1- .
Connect the compressed air hose -2- to the pressure gauge.

Connect the compressed air hose to the compressed air system.

Pull and turn the pressure-regulating valve -3- until the pointer on the pressure loss tester shows 23 % -arrow- .

Lock the pressure-regulating valve. Disconnect compressed air hose.

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

Setting the pressure gauge

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).
Connect the pressure gauge -1- to the adapter -3- .
Secure the pressure gauge wit a tie-wrap -2- and connect the test hose to the adapter -arrow- .

Connect the compressed air hose to the pressure gauge.

Courtesy of PORSCHE CARS NORTH AMERICA, INC.

Connecting pressure gauge to adapter
Check the pressure loss.
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!

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
  
  Pressure loss not within tolerance range:
2. 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 lead gasket)
3. 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
Remove locating pin and turning device from the vibration damper.