December 5, 1960 Bulletin No. SB-816
Specifications
SUBJECT: Torque Values - screws, nuts, bolts, & studs;
(Refer to Service Manuals for torques on engines not listed herein.)
Proper tightening of screws, nuts, etc., is vitally important in properly servicing Johnson engines just as it is for any other machinery.
Pulling screws down too tightly may result in stripped threads which increase labor costs to drill, tap and install heli-coils. Leaving a screw too loose may allow vibration to back it completely out. In some cases, such screws may get into moving parts of the powerhead or gearcase and cause damage to the engine.
A loose screw holding cylinder and crankcase halves may result in an imperfect seal which in turn causes loss of crankcase pressures. Also, the center-bearing crankcase screws are particularly critical on the 10 h.p. engines. Under torquing these center screws allows excessive play of the center crankshaft journals; while over-torquing causes the journals to bind in the bearings. Such overtorquing in turn results in premature wear or burning of bearings and center crankshaft journals due to excessive friction.
Needless to say, the only recommended method for properly tightening screws is by using a torque wrench. Torque wrenches may be purchased at reasonable cost and will rapidly pay for themselves in expert workmanship.
JOHNSON MOTORS
W. W. DeWees
W. W. DeWees
Service Department
WWD:eb
NOTE: Post on your miscellaneous index.