Checking For Loss of Pressure
Checking for loss of pressureTools and materials
Tool kit for testing pressure loss
Information
Test evaluation
Note: Some of the illustrations are not based on the BFD (V6) engine. They simply display the principles involved and are used to make the workflow more comprehensible.
The test does not show any meaningful result on a new engine (i.e. one that hasn't been run).
A difference in pressure loss between the individual cylinders of approx. 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.
Checking for loss of pressure
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.
1. Unscrew all spark plugs.
2. Position cylinder to be tested to ignition TDC and remove tool. The ignition TDC for cylinder 1 (and the remaining cylinders) can be tested using the "dead center finder" contained in the WE1066 Bosch EFAW 210 A pressure loss tester.
3. Screw in the test hose by hand into the spark plug thread and tighten it by hand.
4. Connect the pressure loss tester to the compressed air system.
5. Adjust the scale. To do this, insert the test nozzle at the front into the device.
6. Turn the adjusting wheel until the scale pointer is at the "cal." marking or "23%".
7. 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.
8. Interrupt the compressed air supply and unscrew the test hose.
9. Check the next cylinder by turning the crankshaft through another 120° and check the next cylinder in the firing order.
Firing order: 1 - 5 - 3 - 6 - 2 - 4
10. Remove the test hose once the test is complete and install the spark plugs.