Testing Pressure Loss From the Engine
Testing pressure loss from the enginePreliminary work
Spark Plugs:
1. Unscrew all spark plugs.
Ignition Rod Module Comes Out At TDC:
2. Position the cylinder which is to be tested to ignition TDC and remove tool.
Tool kit for testing pressure loss
Tool Kit For Testing Pressure Loss:
Information
Test evaluation
^ The test does not show any meaningful result on a new engine (i.e. one that hasn't been run in).
^ A difference in pressure loss between the individual cylinders of approximately 5% is not significant.
^ If the test shows an excessive loss of pressure (> 30%), a few drops of oil can be sprayed into the combustion chamber. Repeat the test. If the loss in pressure is now significantly less, the seal between the piston and cylinder is damaged.
^ The air that is escaping causes hissing noises, which provide information about the component that is causing the damage.
If the limit values are exceeded, the engine must be started and the test repeated.
Testing pressure loss from the engine
ATTENTION: Danger of damage or injury if pressure loss tester is operated incorrectly
--> Ensure that operational steps and tips from the tool instruction manual for the Bosch tester are observed at all times.
WARNING: Danger of injury!
^ The crankshaft can turn because of the pressure in the cylinder.
--> The piston must be located accurately in the upper reversing point.
--> Do not touch any belt drive components during the test.
--> Do not insert any tool on the belt pulley of the crankshaft.
Note:
^ The check for loss of pressure can be used to assess the mechanical condition of a combustion engine.
^ 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.
Test Hose:
1. Screw in the test hose by hand into the spark plug thread and tighten it by hand.
2. Connect the pressure loss tester to the compressed air system.
Adjusting The Scale:
3. Adjust the scale. To do this, insert the test nozzle at the front into the device.
Adjusting Wheel:
4. Turn the adjusting wheel until the scale pointer is at the "cal." marking or "23%". The pressure is then equal in the two test chambers of the tool.
Check For Loss Of Pressure:
5. Remove test hose and check that the pointer falls back. Connect the test hose. The value that is displayed should not be greater than 30%. If the loss in pressure is greater, it can be assumed that the engine needs an overhaul.
6. Interrupt the compressed air supply and unscrew the test hose.
7. Check the next cylinder by turning the crankshaft through another 90° and check the next cylinder in the firing order following the instructions provided.
Firing order: 1 - 3 - 7 - 2 - 6 - 5 - 4 - 8
Subsequent work
Spark Plugs:
1. Remove the test hose once the test is complete and install the spark plugs.