Checking Pressure Loss

→ Do not reach into the danger area.

Information 

Read the work steps and tips in the operating instructions for the Bosch tester before performing the pressure loss test. The described Bosch tester 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 tools 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. 
• A pressure loss test is more meaningful than the compression pressure check. 
• The percentage leakage quantity can be used to establish 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 cylinder to be tested to ignition TDC and remove tool. The ignition TDC of cylinder 1 (and the remaining cylinders) can be tested using the "dead centre finder" contained in WE1066 pressure loss tester Bosch EFAW 210 A.
   Fig 1: Locating TDC For Cylinder 1

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2. Screw the test hose into the spark plug thread of cylinder 1 by hand (compression TDC) and tighten hand-tight.
   Fig 2: Locating Test Hose

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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.
   Fig 3: Setting Test Nozzle

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5. Turn the adjusting wheel until the scale pointer is at the "cal." marking or "23%".
   Fig 4: Adjusting Scale

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6. Remove the test nozzle 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 is safe to assume that the engine needs an overhaul.
   Fig 5: Checking Pressure Loss Test

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7. Interrupt the compressed air supply and unscrew the test hose.
8. Check the next cylinder by turning the crankshaft through another 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.