A few weeks back I started getting an alarm at the helm, checked the Smartcraft screen and it called out low pressure on my port sea water pump. Changed out the sensor and two weeks later I'm getting the same alarm. I checked the pump pressure on the screen and it reads 37.5 PSI at Idle and 45 PSI at 2K RPM same as the starboard engine. I alsoreplaced the raw water pump back in July so the pump and impeller are fresh, any thoughts?
8.1 Water Pressure Sensor
- Thread starter Dasch Boat
- Start date
The impeller can certainly get damaged by some debris. Have you taken a look?
When you changed out the sensor, did the pressure return to normal for those two weeks?
Why did you change the raw water pump in the first place? Have the pressures been lower or is this something that just happened recently? Could there be debris or growth on the thru-hull? Is your strainer allowing any air to get sucked in?
When you changed out the sensor, did the pressure return to normal for those two weeks?
Why did you change the raw water pump in the first place? Have the pressures been lower or is this something that just happened recently? Could there be debris or growth on the thru-hull? Is your strainer allowing any air to get sucked in?
scoflaw
Well-Known Member
- Aug 10, 2011
- 6,395
- Boat Info
- 1999 Powerquest legend 260 sx 502 mag
2005 Baja 242 islander 496
- Engines
- 502 mpi Bravo 1
496 mag B1
oem sensor? That's crazy high , not low. Did it reduce your power to 89%?
Espos4
Well-Known Member
Missing any pieces on the old impeller that was replaced in July?
If so, did you find and remove them?
If so, did you find and remove them?
Good point @scoflaw -- what sensor did you use to replace it?
My boat had aftermarket sensors and they read high. One completely stopped working and I replaced with OEM and now I get a normal reading. The other aftermarket one is still there and reads high, even after new Hardin pumps.
My boat had aftermarket sensors and they read high. One completely stopped working and I replaced with OEM and now I get a normal reading. The other aftermarket one is still there and reads high, even after new Hardin pumps.
@Dasch Boat Are you sure that's water pressure not oil pressure?
Pump was changed as it was leaking at the shaft, replaced with Mercruiser part. New sensor is aftermarket, sensor on starboard pump is original. Yes I'm looking at H2O and not oil pressure. What should pressure be reading? Screen reads "OK" at PSI that I'm getting.
Forgot this, screen showed that I was running at reduced power but as I was in a no wake zone it wasn't noticeable. Also engine temps are normal.
Espos4
Well-Known Member
Swap sensors between motors.
See if your high pressure moves to the other motor.
usually 1-3 psi at idle.
15-20 psi cruising.
The aftermarket sensors are not very reliable, even brand new right out of the box.
KevinC
Well-Known Member
Jimmy Buoy
Well-Known Member
- Dec 3, 2008
- 2,468
- Boat Info
- 2003 Cobalt 293
- Engines
- Twin Volvo-Penta 5.0 270hp & DuoProps
These are simple pressure sensors that can be used for oil or water - both the same type of sensor. The oil sensors are 0-100psi but I'm not sure what the range of the water pressure sensors are.
KevinC
Well-Known Member
Merc's water pressure sensor on my 2004 340SDA 8.1 is spec'd out 0-100psi. I am pretty sure we can find an OEM GM sensor to do the same at a fraction of the price and offer decent life. It was my port sensor that went and access was not that great so I went the OEM Merc route rather than risk getting a piece of junk from China that could fail putting me in guardian mode.
-Kevin
I'll replace the sensor later this week and report back.