Diagnose Low Water pressure 5.7L 350

Todd320

Well-Known Member
Jul 21, 2016
1,508
St. Petersburg, FL
Boat Info
2007 Sea Ray 320DA
Engines
Twin V-drive 5.7L 350 Horizon
I have Horizon 5.7L mpi fresh water cooled engines 2007-ish). Received an alarm at 3900 rpm, low water pressure.
Had to keep that engine at idle the rest of the way home (ran just fine the entire day, last mile in after stopping to enjoy the calm water). I have a mechanic, but I know it could just be a blockage in the strainer if I sucked something up. So, first I’m Climbing under the boat to remove any grass/crap in the intake. Then I’m going to clean the strainer. Then I’m going to replace the water pressure sensor, I have a spare. Anything else relatively simple before I get the mechanic involved? It very well might be a bad water pump, already replaced the port, so starboard is going to go soon.
 
If it only alarmed at 3900, but not idle, probably something sucked up, partially blocking something, likely the strainer.

I think you're on it. Id look in the strainer first before going overboard, unless looking for a reason for a swim. I'd hold replacing expensive stuff until the known choke points are clear.
 
You are on the right track. I would check the strainer first before going over the side to check the intake. If you don’t want to get in the water, close the seacock, remove the hose from the seacock, and re-open and close it quickly. If water shoots through the seacock like a high pressure hose then your intake is clear. If not, it might be time for a swim...
 
Boat will be on the rack when I get there, that’s why I was going check there first. And last time I was there I was searching for where the transducers are located, and I noticed a small amount of grass in the intake, but did not have any tool to get it out (I’m assuming the grill just comes off with a screw driver?)
Appreciate the help! Thanks!!
 
Well, sort of like I expected. Little bit of grass in the intake, nothing major, nothing in the strainer. Replaced water pressure sensor just in case. Cranked engine, belts, pump, did not look right, I ran back and turned off the engine. Not sure exactly what I saw, but pretty sure the belt was not spinning. So, just like my port engine, the alternator or something is locked up and so the tech is called. Hopefully less than 2 boat dollars!
 
As much as I hate it. I generally do things in tandem because I figure its going to happen on the other engine too.
 
If you want try something yourself, take the belt off and spin every accessory pulley by hand and locate the culprit. If everything spins, start it up again and take a better look at things. If you're not comfortable with replacing any of the accessories yourself, then there's probably no reason to do that as it won't save any time for your mechanic - he'll check all that out, anyways.
 
If you want try something yourself, take the belt off and spin every accessory pulley by hand and locate the culprit. If everything spins, start it up again and take a better look at things. If you're not comfortable with replacing any of the accessories yourself, then there's probably no reason to do that as it won't save any time for your mechanic - he'll check all that out, anyways.
I’d like to think I could do it, but I’m just so freaking slow when I do work like this.
 
I’d like to think I could do it, but I’m just so freaking slow when I do work like this.
No worries - it's good to keep food on your mechanic's table! :)

Besides, with v-drives, it's done a little bit more by "feel" since the engines are backwards. Which makes it a little more challenging the first few times you do it.
 
Where is the water pressure sensor and what does it look like?
shopping.png
B352CF9F-43EA-4927-9A78-970E5CB8DC2D.jpg
 

Forum statistics

Threads
112,945
Messages
1,422,731
Members
60,927
Latest member
Jaguar65
Back
Top