goldeneyee

Scanned both 496 Ho engines with Rhinda and the sea water pump port engine pressure at idle is 3 lbs and at 2000 Rpm is 9.6 lbs. The Starboard engine at 2000 Rpm is 40.7(at 2000) and 41.6 (at 650) lbs pressure. What gives? Could it be a defective pressure sensor? Exhaust manifold heat was nearly the same for both engines just over 100 degrees. Could it be a blockage in the stbd. oil cooler or some other place? Looking for suggestions before I start taking this puppy apart. Thanks... Bill ps. What's the pressure when new?

SDFever

I just had the exact same issue. I ordered a new sensor and then the problem went away after I messed with it some... The ecm maxes out right around the lower 40's on pressure. Make sure the plug is clean etc...

The digital water sensor is the same as the digital oil pressure sender. Rinda has a sensor test lead kit you can buy that helps eliminate incorrect diagnostics. It's around 89 bucks and it allows you to power and read the sensor for test..

If exhaust temps are all consistent and there is no over heat then chances are you don't need to take it apart.

simon1401

496 seawater pumps are prone to getting scoring on the end plates, as they are brass rather than stainless. This makes them struggle to pick up water at idle but as soon as revved up they are usually fine.
You may want to verify with a pressure gauge before getting to deeply into replacing parts.