Component Tests and General Diagnostics

Leak detecting cylinder

Operation number: 21003-2

Note! Some variation in the illustrations may occur, but the essential information is always correct.






Preparatory work

Run the engine to operating temperature so that the thermostat is open.
Remove the spark plugs. Refer to: Spark plugs, B6304T4, B6324S5, B6324S4 Service and Repair

Cylinder leakage test





951 2775 Cylinder leak tester 951 2775 Cylinder Leak Tester


Cylinder leakage test
- make sure that the piston to be measured is at top dead center in the compression phase.
- connect a metered air pressure to the relevant cylinder via an adapter that is secured in the spark plug / glow plug well.
- A gauge is used to measure the size of the leakage from the cylinder.
The gauge is a pressure sensor with a regulator and displays the size of the leak expressed as a percentage.

Fault-tracing

The source of a leak can be located by analyzing sound at the following points.







Note! There is leakage at the piston rings even on a perfect engine. This is the only place where a small leak is permissible.

Check
If a leak is detected that is assumed to come from the valve system, first check that the piston in the relevant cylinder is at top dead center (TDC). Then try to set the piston just before top dead center (TDC) and redo the test. When repeating the leak test on the same engine, there are usually variations in the results of the measurements. This is due to changes in the engine coolant temperature (ECT) and the piston not reaching the same position as in the previous test, and is affected by the amount of oil on the piston rings at the time.

Finishing

Install the spark plugs. Refer to: Spark plugs, B6304T4, B6324S5, B6324S4 Service and Repair.