Im trying to figure out what my water pressure range should be, at idle im getting 5 at most WOT im getting 10-12 has new impeller, never over heats, just seems low to me, this is a new to me motor.
Re: 2000 Mercury 150 2 stroke water pressure question
Most motors will get up to 5 LBS. water pressure at idle when the motor is cold and will be sum less after warmed up and the thermostat opens up. When the motor is at WOT the popit valves open up and let more water flow thru the motor to keep it cool. Most will run up to 18 LBS. at WOT and should not go much over that. If it excedies that then there is a blockage of the water cooling system and the motor will overheat. When at idle the water pressure will be less than the 5 LBS. and might even go to 1 LBS.with the motor warm. When this happens you should check the tell tail stream to see if it is hot to where you cannot hold your hand in it. The low pressure is a sign that the impeller in the water pump is not getting water or that it is getting worn and needs to be replced. Even tho the impeller is new, if the cup and base plate of the pump were not replaced, will/could cause lower pressures because the old impeller will cut groves in them and a new impeller will not always seal at that point and cause lower pressures. If there are deep groves in them they should be replaced with new when repairing/ replacing the impeller. JMO
Oldman570
Re: 2000 Mercury 150 2 stroke water pressure question
ok... so im lost in your response... Are my readings correct?, the motor only has 58 hours on it, it basicly sat in an insulated shop under cover for most of its life. I replaced the impeller as a precaution. I ran it this weekend at WOT for about an hour and it never over heated or any warning beeps of any kind. so are my readings within the safe zone?
Re: 2000 Mercury 150 2 stroke water pressure question
Your readings are OK but alittle low for a new impeller. The one that I would like to see higher is the WOT reading. You did not say if the gauge use an electric sending unit or a tube from the motor to the gauge. I perfer the tube style myself as it is more reliable than a electric sending unit. There are several things that could cause you readings to be low. Where the tube or sender is located on the motor, gauge not reading corectly are the most common ones that I have seen. The main thing is that the gauge dose show that there is pressure from the pump. The Faira gauges web site has good info on it for a pressure gauge, or best is to call the manufacture of the gauge and talk to a tech about your readings to see what they say. When trying to get good readings of any pressure a high quality guage is a must. Even the way it is installed can make a diffrance in the readings. JMO
Oldman570
Re: 2000 Mercury 150 2 stroke water pressure question
Aussie is correct. Mercs never have any higher water pressure. Now my Johnny will peg a 30PSI gauge, when on plane at 2/3 throttle, but that is a different animal.
