water pressure
 

i have a 96 502 magnum. i put a water pressure gauge on the sea water pump. i was wondering what it should read? thanks

U should take it of the intake manifold ( thermostat housing ) ..to get a good reading of the engine !!!!!

It should read not less then 15 WOT and not more the 28 WOT !!!!!!!!!

5psi at idle,,,,20-30 at speed,,,thats what mine read

i just put a hardin marine stainless sea water pump on with a new autometer gauge off the 1/8" fitting on the pump. i have 0 idle and about 5 or 6 pounds at 3000 rpm. any guesses? thanks. it is pumping water at an idle coming out of the pipes. it seems to actually have a slight vacuum at the gauge line when it's idling

Not really sure about the gauge on the pump concept. I would be more concerned about water pressure in the block.

Fixx
 

Get the line away from the sea pump and try plumbing it into the front of the intake..

ok. i will try that tomorrow. odd , thats what they said the pump was tapped for was a pressure gauge thanks

X2 Pressure in the block is what matters.

Are your numbers running the boat on the hose, running it in neutral at the dock or actually running the boat???? It makes a big difference.

i just had it running on the hose.

Water pressure numbers on the hose are worthless other than at a fast idle. You need to run the boat at speed for real numbers. A hose can't supply enough water for accurate readings and does not duplicate the water being forced in by the speed of the drive/pickup going through the water.

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

Mine is plumbed into the intake, next to the thermostat.
1/8 tube to the autometer gauge.

barely reads anything at idle. 10-15psi at speeds below 50 20-25 at 50-60mph. 25-35 at 60-80mph. I also have a low water pickup, which I think adds to the higher psi.

I plan to instal a relief valve pretty soon.

I had the a similar problem, it has been brought up before and the post have gotten banned.

x 2