Replace cylinder head valve guide

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FIGURE 4-23. Valve Lapping.

TM-55-1905-223-24-1 Main Propulsion Engine for Landing Craft Utility (LCU) NSN 1905-01-154-1191 Manual

FIGURE 4-25. Valve Seat Insert Removal.

TM 55-1905-223-24-1

d. Replace cylinder head valve guide.

CAUTION

If a valve guide is replaced, the valve seat

insert for the valve guide must be ground. The

inside diameter of the guide establishes the

centerline of the valve location. The bore center

in the new guide can be slightly different from

the old guide.

NOTE

Only replace valve guide if it is not to specification.

(1) Use a valve guide mandrel (1, FIG. 4-24) and a valve guide arbor press to remove the valve guide

(2).

(2) Measure inside diameter of guide bore. Verify inside diameter is between 0.8435 inch (21.425 mm)

and 0.8445 (21.450 mm).

FIGURE 4-24. Valve Guide Removal.

NOTE

Valve guides are available in 0.010 inch (0.25 mm)

and 0.015 inch (0.38 mm) oversizes.

(3) If the bore is not within specifications, use reamer to enlarge the bore for oversize valve guides.

Ream the bore to maintain a press fit within 0.0011 to 0.0026 inch (0.028 mm to 0.067 mm) between

the valve guide and the valve guide bore.

(4) Use valve guide driver to install valve guide. Verify valve guide installed height of 1.375 inch (34.93

mm) by using machinist rule.

e. Replace valve seat insert.

4-23