Section IV. VALVES

TM 5-4110-217-14

cracks, dents, and broken fins. Replace defective parts.

NOTE

c. Installation.

Do not use a pry to loosen the cylinder

(1) Install new cylinder head gasket (166) on

head It may damage the head or

crankcase.

crankcase A soft-faced hammer may be

(2) Align holes in gasket (166) and cylinder

carefully used to sharply tap the cylinder

head (161) with holes in crankcase with nine bolts (163 &

head edge Take care not to break any

165) and washers (164). Tighten bolts to a torque of 5

cooling fins

foot-pounds; then 1 foot-pounds, etc., until all are

b. Cleaning and Inspection.

torqued to 29 to 31 foot-pounds. Refer to figure 5-15 for

(1) Carefully clean cylinder head, crankcase,

head bolt tightening sequence.

and top of piston with scraper or wire brush. Use

(3) Install spark plug (84) gasket (85) and

approved cleaning solvent to clean all applicable parts.

connect ignition cables (220 and 221).

Dry parts thoroughly.

(2) Inspect all threaded parts for damaged

threads. Inspect cylinder head and crankcase for

Section IV. VALVES

revolution and again line up the TC marks. Then follow

5-16. General.

the adjustment given for the valves of the left hand

Positive type valve rotors are furnished in this model

cylinder.

engine The action of the rotor cap, which rotates the

valve slightly each time the valve opens, helps prevent

5-18. Removal of Valves (Figure 3-11).

sticking valves, and will impart a wiping action between

the valve face and valve seat, thereby preventing the

buildup of foreign deposits. Valve rotation will also avoid

If a valve face is burned or warped, or the stem is worn,

prolonged exposure of any one section of the valve face

install a-new valve

to a local hot spot on the seat which will result in lower

a. Remove engine from refrigeration unit (para 3-

and more uniform valve face and seat temperatures.

22).

b. Remove cylinder head (para 5-15).

5-17. Valve Tappet Adjustment.

c. Remove valve tappet cover (para 5-16a).

a. Valve Tappet Inspection Cover Removal (fig. 3-

d. Using valve spring compressor Onan Part No.

11).

420-0119, compress valve spring (172). Remove valve

(1) Remove screw (158) and washer (159) that

spring washer lock (169) from valve stems.

attaches valve tappet inspection cover (157) to

crankcase.

(2) Remove inspection cover and gasket

(160).

b. Adjustment.

(1) Crank the engine over slowly by hand until

the left hand intake valve, when facing the flywheel,

opens and closes. Continue about 1/4 turn until the TC

marks are aligned. This should place the left hand piston

at the top of its compression stroke which is the position

it must be in to get proper valve adjustment for the left

hand cylinder.

(2) Clearances are indicated in para. 1-5. For

each valve, the gauge should just pass between the

valve stem and valve tappet (figure 5-16).

(3) To correct the valve clearance, turn the

valve adjusting screw as needed to obtain the right

clearance. The screw is self-locking (figure 5-17).

(4) To adjust the valves on the right hand

cylinder, crank the engine over one complete

Figure 5-16. Adjusting Tappets (Model RMP-J/1-1OG)

Change 3 5-10