Re: What should the water pressure be on 70hp JOHNSON 1990
Topwater,That is a figure that varies from engine to engine and is model specific depending on the amount of backpressure that your thermostat assy and waterpump indicator pose on the cooling system.Typically at WOT expect somewhere around 15-18 psi depending on the health of your waterpump.The 95 70 rude I own was recently fitted with a new waterpump assy and the updated kit contained a revision in the waterpump indicator line.Basically it did away with the flow restrictor that was fitted through the engine pan and recommended routing hose through a grommet and discharges through a 1/4 i.d. hose.it also included changing the thermostat cover and spring to one of different load.This lowered waterpressure about 3 psi however increased volume.I believe this was done in the wake of a bulliten on exhaust cover and head cover gasket leak potential.
