1999 "EE" Evinrude 70HP 4-Stroke Service Manual, P/N 787023, Page 35Get this manual
Special Operating Conditions Salt Water
Fresh water internal flushing is recommended after use in salt, polluted, or brackish water to prevent deposits from clogging the cooling passages
Motor can be stopped or running at idle while flushingDo not flush engine with water system that exceeds 45 PSI
During long periods of non-use, tilt motor so that the gearcase is out ofthe water, unless the temperature is below 32 (00 C)When removing motor from water, allow cooling system to drain completely by placing motor in normal (vertical) position
Weedy Water
Weeds can block the water intakes and cause engine to overheatWeeds on the propeller will cause motor to vibrate Run at slow speeds and reverse motor frequently to clear weeds from propellerCheck water pump indicator oftenRemove weeds from propeller and water intakes before operating in clear water