Normal water pressure

[YN2(SS)]

I just completed a rebuild of my lower unit and have a strong tattletale stream. Now that I can hook up my water pressure gauge and expect to see something, what is a reasonable water pressure for a 1980 Mercury 70 outboard?

 

[Faztbullet]

You need a 0-15 psi guage and it will have 1-2 psi at idle and about 6-8 at WOT

 

[bruceb58]

The specs for my outboard in my sig is 2-7PSI at idle and 6-20 PSI at 5500RPM. Mine runs 15 PSI at 4000 PSI.

 

[ajgraz]

You likely will not like using a water pressure gage with that old 70hp motor. That model has what Merc calls a "high volume" rather than "high pressure" pump. You're likely to get low, erratic pressure readings all the time.

You should consider a temp gage instead.