water pressure drop with rpm increase?
 

Trying to diagnose what i think is low water low. I am running a 502mpi. Was pressure is around 3psi at idea and increases to 15psi at 3000 rpm. as I increase RPM the water pressure drops to 10psi or so. I'm concerned about water pressure because I have steam coming from port side exhaust. Water Temp runs around 175 pretty much all of the time. even at higher rpms. I have check for restrictions from raw water pump to engine and don't have any. Thoughts? Thanks

Sounds like the impeller, housing or both may worn out. How old ?