What is the correct amount of waer pressure for a stock HP525EFI? I have them in my boat, and according to my smartcraft monitors I have about 1.2 the water pressure in one engine compared to the other. The port engines reads about 2 psi at idle, and 18 psi at 4k RPM, and the starboard engine reads about 4 psi at idle and 35 psi at 4k RPM.

Both engines run the same temp, but I want to get this checked out.

Those sensors are pretty unreliable, so feel the hoses and see if one feels harder than the other one. Is there beeping?

Mine idle at 6-8 lbs. and 25-30 @ 4000 rpms and I have water pressure relief valves on mine.

No beeping or any noticeable difference between the two motors in terms of water temp, RPM, oil psi, or anything else. These readings are coming from the Smartcraft monitors, so I thought that they would be pretty accurate.

Mine idle at about 5 psi on the port and a bit more on the starboard. Underway the port is always about 5 psi less than the starboard, but not as low as yours. I've talked to several folks who have water pressure gauges on their motors and they all say the port always read less than the star.

Wonder why that is?

1.2 psi at idle is an idication your impeller is worn, or your hosing is worn making a new impeller useless.

Your starboard motor is in the norm range for a good pump barring any clogging in the oil cooler or heat exchanger.

I've got a mechanical gauge on mine and the gauge is off the charts at WOT, I suspect it's due to the DWP on the lower. I've read in Teague On Tech that it helps to cap off some of the side inlets, any thoughts on that. I know I need to lower the psi but didn't think it was crucial on the closed cooled system. I might have to go to a water relief valve. Sorry, didn't mean to hijack your thread! Steve

The impeller and housing on the starboard motor have been replaced 2x recently - I suspect there is something blocking water flow somewhere and will have it checked out.

I think I was reading close to 40 last time out. I also noticed at idle on the trailer that there was less water, and it was hotter coming out of the port exhaust than the starboard. Backflushed header and it is fine. The heat exchanger is the last thing before the headers. Is it possible to open that up and see if it's clogged and clean? The previous owner did not use a strainer but I am now and my impeller is new on the pump as well. PS: I have a 525 as well.

I called Merc and talked to them about the fact that one side is putting out more water than the other at idle. He said this was normal. I also asked him about water pressures at WOT. He stated 35-38 was normal and 40 is not too out of line.