I think mine is about 2 lbs at idle in the water, goes up to about 12 lbs at 3/4 throttle. I also have a pressure relief valve that will start trickling water at about 45 mph. Don't know if this is correct or not, but it's been this way since i've had it. I have my pick off at the thermostat housing.

Just wanted to add that this is on a standard bravo with the standard water pick up, with a nose cone. 502 MPI. Impeller in the sea pump has about 35 hours on it.

I have a 454 with a Mercury pressure relif valve.
I run between 7-15 max depending on trim.
I also have a shorty.

I thought this was way too low as the pressure releif is "set" for 30 or so pounds so I am told. Changed out the water pressure gauge with another new one (Autometer) and they both read the same.

I have no over heating issues, boat runs 160-170.

Ken

No problem with those pressures as long as the engine maintains temp. The merc relief valves are set at 25psi. You really don't need one with your pressures and it should not be dumping any water. Where are you getting your pressure reading from????

well i had the plastic pump crack when the impeller came apart so i put the stainless pump on. lot of water comes in when the pump cracks !! have about 5 hours on the pump then blew the hose going from the pump to the oil cooler. sooo i put good hose back on there instead of the molded hose junk and an autometer pressure gauge in. just a stock 502 mag mpi in a 96 272 but i was expecting the pressure to be much higher with a new pump and cold with the thermostat closed. hardin directions say the side of the pump is tapped for a pressure gauge but those can't be the right readings. but then again you guys seem to have low readings too. twin spins says he gets about 20-30 running, that was more what i was expecting. thanks

The way I think about it, is most vehicles have a 15psi radiator cap. Trucks, cars whatever. I don't see any reason why a boat motor would need over that either. As long as the water temp holds at your thermostat setting.

Griff, I have my pressure line plumbed into the T-stat housing on the starboard side
There was a plug there and i used the hole.

Dumps water at 1500 RPM.

Ken

i have 468s., at idel ive never had pressure acording to my guage, but at running speeds i get anywhare 5 to 20 psi, boat never runs hot idel after running temp is about 150- running about 120-140, my boat has always run cool and very good, and i have a crossover pipe!

Stock 454, 5 psi high idling (with a new impeller), about 10 psi when running.

excellent point. i don't know why i didn't think of that. you are correct. for some reason i thought it would be higher. thanks

I was just told this past weekend that I should plumb the water pressure line somewere BELOW the thermostat. Right now I am above it.

Should this make a difference?

Ken