While flushing the motor, Test the h2o pump to be sure it has very good water movement. very carefully place your finger through the stream of drinking water exiting the motor.
Whether it is OEM or aftermarket Mercury https://brendasafg196560.blogitright.com/29820824/how-much-you-need-to-expect-you-ll-pay-for-a-good-inflatable-boat-outboard-engine