Checking Pressure Loss

Information 

Read the work steps and tips in the attached operating instructions before starting the pressure loss test. The device described here is used as an example for all suitable pressure loss testers. Details of calibration and use can be found in the relevant operating instructions.

Information 

The piston must be exactly at the upper return point when checking pressure loss. Do not touch any components of the belt drive and do not put any took on the crankshaft pulley while performing the check.

Information 

• The check for loss of pressure can be used to assess the mechanical condition of a combustion engine. 
• pressure loss test is more meaningful than the compression pressure check. 
• The percentage leakage quantity can be used to determine whether the leaks in the combustion chamber in question are so large that the combustion chamber must be repaired. 
• The worn components (e.g. piston rings) can be identified by the compressed air that is escaping. 

1. Position the cylinder to be tested at ignition TDC and remove tool. The ignition TDC for cylinder 1 (and the remaining cylinders) can be checked using the "dead center finder".

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   TDC for cylinder 1 

2. Screw the test hose into the spark plug thread of cylinder 1 by hand (ignition TDC) and tighten hand-tight.

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   Test hose 

3. Connect the pressure loss tester to the compressed air system.
4. Adjust the scale. To do this, insert the test nozzle at the front into the device.

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   Test nozzle 

5. Turn the adjusting wheel until the scale pointer is at the "cal." marking or "23%".

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   Adjusting the scale 

6. Remove test hose and check that the pointer falls back. Connect the test hose. The value that is displayed should not be greater than 25%. If the loss in pressure is greater, it can be assumed that the engine needs an overhaul.

   Courtesy of PORSCHE CARS NORTH AMERICA, INC.

   Pressure loss test 

7. Interrupt the compressed air supply and unscrew the test hose.
8. To check the next cylinder, turn the crankshaft by a further 120° and check the next cylinder in the firing order.

   V6 firing order: 1 - 5 - 3 - 6 - 2 - 4 

9. Remove the test hose once the test is complete.