Cylinder Head - Vacuum Test Valve Seating (2-09) Section 2 - Cylinder Head - Group 02 M11 Page 2-32 Move the toggle switch (1) to the position. Turn the vacuum control valve (2) to the ‘‘OPEN’’ position. NOTE: The vacuum control valve is in the ‘‘OPEN’’ position if the vacuum gauge needle moves clockwise . Operate the vacuum pump until the gauge indicates the specified vacuum. Valve to Valve Seat Vacuum mm-Hg in-Hg 508 MIN 20 685 MAX 25 Turn the toggle switch (1) to the position. Use a stopwatch and start timing when the needle on the gauge indicates 457mm-Hg [18 in.Hg]. Stop timing when the needle on the gauge indicates 203mm Hg [8 in.Hg].
The elapsed time for the needle to move between the specified gauge readings must be 10 seconds or more. If the elapsed time is less than 10 seconds perform the following checks: Repeat the test to be sure the equipment is oper- ating properly. Use a mallet to hit the valve stem lightly to make sure the valve is seated. Repeat the test. Apply a thin layer of grease on the outside diameters of the insert and the valve head. Repeat the test. The grease pattern will show the point of leakage. A break in the grease seal pattern will indicate leakage between the valves and valve seat or the valve seat insert and the cylinder head. Refer to Cylinder Head - Rebuild (2-02).