TM 9-6115-604-34NAVFAC P-8-633-34NOTECup number ST-1 257-38 is used for testing both intake and exhaust valves. Use seal ST-1257-36 for testing exhaust valves, and seal ST-1 257-37 for testing intake valves.(a) Install the cup on the vacuum hose, coat the seal with petrolatum, VV-P-236, and install it in the cup.(b) Place the cup on a dean, flat piece of plate glass, turn on the pump, and open the shutoff valve.(c) When the vacuum gage reaches 1 8 to 25 inches Hg (60.8 to 84.4 kPa), dose the shutoff valve toisolate the gage, hoses, and cup.(d) If vacuum will not reach 18 to 25 inches Hg (60.8 to 84.4 kPa), or the gage drops after dosing theshutoff valve, leakage in the hoses or fittings is indicated. Repair leaks before combing the testprocedure.(2)Coat the seal with petrolatum VV-P-236, and place the cup over the valve so that the seal rests on thehead surface (Figure 9-11).(3)Operate the vacuum pump to pull a vacuum of 18 to 25 inches Hg (60.8 to 84.4 kPa) over the head of thevalve.(4)Close the shutoff valve, and time the vacuum drop from 18 to 8 inches Hg (60.8 kPa to 27.0 kPa).(5)If the elapsed time is less than 10 seconds, leakage is indicated. To be sure the valve is seated, tap thestem and of the valve with a soft, light hammer and retest.(6)If leakage is still indicated, remove the cup, and seal the outer edge of the valve seat insert and cylinderhead joint with grease. Repeat the vacuum test (timing will not be necessary).(7)Remove the cup and examine the grease seal. If breaks in the grease seal are found, leakage is indicatedbetween the valve seat insert and the cylinder head counterbore. Re-stake or replace the valve seat insertin accordance with paragraph 9-11.(8)If the grease seal is intact, leakage at the valve seat is indicated.(9)Lap the valve and seat lightly using lapping compound SS-L-1 682, and repeat the timed vacuum test. Ifleak down still occurs in under 10 seconds, a complete check of reseating equipment and operatingprocedures should be made; a properly finished seat will hold vacuum for 10 seconds or more.g.Preservation. If assembled head is to be stored, spray all surfaces with preservative oil MIL-L-21260. Whilespraying, lift each valve slightly to be sure preservative oil penetrates to the seat area9-10. CYLINDER HEAD ASSEMBLES INSTALLATION. Install the cylinder heads as follows (see Figure 9-1, Figure 9-2, and Figure 9-12):WARNINGCompressed air used for cleaning or drying can create airborne particles that may enter theeyes. Pressure shall not exceed 30 psi (207 kPa). Wearing of goggles Is required to avoidInjury to personnel.CAUTIONTo avoid cylinder head leakage, clean all traces of old gaskets and carbon from the cylinderhead and cylinder block gasket surfaces. During cleaning, plug all holes In the cylinder blockto prevent entrance of dirt. Be especially careful that dirt does not block the orifice In the oilrestrictor expansion plug. To avoid false torque readings, clean all capscrews and threadedholes using thread chasers, taps and dies, and compressed air as necessary.a.Place a new cylinder head gasket (13, Figure 9-1) over the dowel pins in the cylinder block The word TOP mustbe visible when the gasket is in the installed position.b.Install four new water seal grommets (14), three new push rod tube grommets (15), one new oil seal grommet(16), and one new cylinder head capscrew grommet (17) in the cylinder head gasket (13).9-18
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