1999 "EE" Evinrude 70HP 4-Stroke Service Manual, P/N 787023, Page 34Get this manual
6Inspect propeller shaft seals for evidence of leakageReplace if necessary7Drain and refill gearcaseLubricate all components of engineSee Lubrication, this section8Check propeller conditionReplace if damaged 9Retorque all screws and nuts to specifications10Run engine in test tank with correct test propellerCheck cooling system operation11To remove carbon deposits from combustion chambers and pistons, inject OMC Engine TunerLet tuner soak in engine between three and sixteen hoursAfter soaking, run engine at fast idle (1500 RPM) for at least 15 minutes at normal operating temperature INotel
During engine operation, carbon can build up on internal powerhead components, eventually causing piston rings to "stick Adding OMC Carbon Guard fuel additive to every tank of fuel is your best protection against such buildup and the resulting mechanical problemsIf OMC Carbon Guard is not used consistently in the fuel, OMC Engine Tuner should be applied every 50 operating hours12Check engine operation by verifying minimum test propeller RPM Refer to Engine Specifications, this section