I made a post awhile back about this and since I have done a few things and need help for next step.
I have ZF gears, I think they are 301A2's My starboard pressure gauge is reading 300 psi my port is now reading 225 psi. Last time I took the boat out I did run it up to WOT and both rpms were equal so no slippage I was aware of. I have changed out the gear oil and changed out the spin on filters and cleaned out the suction filters on both trannys. Made absolutely no change in pressure. Today I swapped sending units and no change. Now when I turn motors on the pressure goes to the readings I mentioned above. This is at idle speed. It does not change when under way or at higher rpms, neither trannys for that fact. It states on the side of transmisson that minimum pressure should be at 296.
Now for a little histry- I also had a DC volt leak on that motor a month or so ago. I also noticed my boost pressure is now really low on the port engine. But the motor does run out fine. So I am at a dilema if I have actual problems , or some wire interfence issues from the dc volt leakage. I was hoping when I changed sending units I would see a difference but everything reads the same as before. If it were a actual transmission issue where to look next, and why does pressure not increase or change with rpms change? does anyone else run with transmission gauges that could chime in ? I want to get through this issue then try and figure out why boost gauge readings are lower on port motor. Thanks Brad