Figure 4-24. Checking Fire Ring Groove in Piston Crown Using Tool J24599 .

TM 55-1930-208-24

d. Inspection.

(1) Check tapered fire ring groove width in the current piston crown with tool J24599 as shown in figure 4-24.

Slide the "NO-GO" wire (.106 inch diameter) of the tool completely around fire ring groove. Should the wire

be below flush at any one area, the piston crown must be replaced. The "GO" wire (.100 inch diameter)

should be flush or protrude slightly from fire ring groove.

(2) Check cylinder liner and block bore for excessive out-of-round, taper or high spots which could cause failure

of piston (refer to paragraph 4-12 for specifications).

Figure 4-24 .

Checking Fire Ring Groove in Piston Crown Using Tool J24599 .

4-33