TM 9-6115-604-34NAVFAC P-8-633-34Figure 9-11. Vacuum Testing Valve Seats Using ST-1257(4)If necessary, add a maximum of two valve spring shims under the valve spring guide (4), to adjust theassembled valve spring height to not over 2.470 inches (62.74 mm).(5)If the correct valve spring assembled height cannot be obtained with two shims, the valve, the seat insert,or both the valve and the seat insert must be replaced. See paragraph 9-11 for valve seal insertreplacement procedures.(6)Remove locks (1), seats (2), spring (3), and guide (4). Install shims (if necessary), guide (4), spring (3),and seat (2) over valve (5 or 6).(7)Using valve spring compressor ST-448-6, compress spring (3), and install new locks (1).(8)Install the remaining valves using steps (1) through (6), above.f.Vacuum Test. Check for satisfactory valve sealing using valve vacuum tester ST-1 257, as follows (see Figure9-11):CAUTIONNever vacuum test a cylinder head with the injectors installed The installation of injectorswhile the head is removed from the block could cause misalignment to the halves In the valveseat area resulting In leakage during testing. This leakage would not necessarily occur duringactual engine operation.(1)Before testing for valve leakage, check vacuum tester ST-1257, for leaks as follows:9-17
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