Re: Nissan 18e2 hesitation
Most of the time you can not judge a gasket failure by a compression test, as the water leak into combustion chambers is very small at the moment, will worsen with more use, bear in mind thast one story is with engine at idle, other runing at load at fast rpm that generates more heat and metal dilatation Try re torquing head to 30 Newton Meters, with time/use gaskets compresses, hardens, the perfect combustion chamber seal is lost as when new factory delivered. If adjusting head gasket doesn't solve the problem, a new head gasket with impecable clean crank case and cylinder head mating surfaces is mandatory.
You will need to change base gasket as well, have a thermostat check, if very old looking, replace it too along thermo gasket. Take advantage to decarbon pistons, exhaust ports & cylinder head if needed. Once done and before placing crank case at base, with a small brush apply several coats of black enamel paint to the gasket crank case/head contour to seal it better. You will need to retorque new head gasket after two 20 worked hours intervals to finally sit at factory torque specs.
Tohatsu recommends a complete service at each 300 worked hours, assume head gaskets and related parts are changed at dealer, but boaters engines that don't visit delears for deep maintenance issues bypasses this very important part in order to achieve perfect undisturbed combustion.
