Port engine overheats after running into sand bar.

skunkman

Active Member
May 27, 2014
452
Longboat Key
Boat Info
2014 330 DA sold
Current boat 2021 Formula 350CBR
Engines
Triple 350 Mercury Verado
I did a real bone head thing yesterday and got my boat stuck in sand and sea grass. I tried to reverse out and couldn't. Seatow couldn't pull me out so I anchored and waited for the tide to come in today. Now the port engine is overheating. I shut the engine down. I imagine I sucked up sand and or grass. Any advice? Should I flush the engine? Check the impeller? Thermostat?
 
I did a real bone head thing yesterday and got my boat stuck in sand and sea grass. I tried to reverse out and couldn't. Seatow couldn't pull me out so I anchored and waited for the tide to come in today. Now the port engine is overheating. I shut the engine down. I imagine I sucked up sand and or grass. Any advice? Should I flush the engine? Check the impeller? Thermostat?

Yep. Clean the basket, check the impeller and flush everything out.
 
Back flush everything! Also if the intake is under the boat check it as well
 
Heat Exchanger might be packed with sand too. Take the end caps off and check it out.
 
I have fittings on my swim platform I use to flush the engines. But, how do I backlash the engines?
 
I’m thinking the only way to avoid getting water in your cylinders is to pull the hoses off the bottom of the manifold and flush from there backwards I’m pretty sure from that point south there’s no risk of water intrusion but on a different note are you seeing reduced water flow out of your exhaust or do you have outdrives where you can’t see her discharge ? Happened to me once a few years ago I think the biggest risk is the sand score the backing plate and the impeller in the water pump so that’s pretty much where you going to see a reduction in water flow if you change your impeller it should be pretty obvious if there’s damage Good luck and don’t sweat it
 
Sorry, that sucks! I'd highly recommend pulling all coolers and flush both motors/hoses.
Oil cooler
Steering cooler
Trany cooler
Fuel cooler
Heat exchanger
 
Sorry, that sucks! I'd highly recommend pulling all coolers and flush both motors/hoses.
Oil cooler
Steering cooler
Trany cooler
Fuel cooler
Heat exchanger

I'm pretty handy with cars but I don't know where those parts are. Anyone have a schematic or pictures that could guide me. I do know where the water pump is and am capable of inspecting and changing the impeller and plate.
 
a m350.jpg

Here is the engine. Raw water pump left lower correct?
 
Last edited:
I'm pretty handy with cars but I don't know where those parts are. Anyone have a schematic or pictures that could guide me. I do know where the water pump is and am capable of inspecting and changing the impeller and plate.

Here's some friendly advise: If you aren't sure of what you are doing or why, get a mechanic to come onboard and assist you. Overheating an engine can have dire consequences and now is not the time to take the cheap way out as it will cost dearly if you miss something.
 
Here's some friendly advise: If you aren't sure of what you are doing or why, get a mechanic to come onboard and assist you. Overheating an engine can have dire consequences and now is not the time to take the cheap way out as it will cost dearly if you miss something.

Thank you for the advice. At this time I am trying to get educated. The cooling system is obviously quite different than a car. Not too long ago my shift actuator went out and through the help of this forum I was able to get a new one, install it and get the boat boat running again. Not trying to be cheap - I just want to learn as much as I can. I also replaced an alternator and now know how to easily change the serpentine belt. If one breaks when I am out I have a spare and now can easily get the engine going in no time.
 
Get in close to your engines. I mean get in there and just study them. Start with the water intake from the strainer. Follow the hose and see what it links too. Most coolers are about 1foot long and have water in and out with oil in and out on separate lines. The water hoses have hose clamps. The oil lines are compression fittings. Easy on off plug and play. Just hard to get too.

Oil coolers are generally on the same side as your filter but much lower. Tranny coolers are usually on top horizontal to the transmission. Steering coolers if it drives are usually near the steering pump. The heat exchanger is on the top back of the engine. Fuel coolers are near fuel pumps.

Just look for hose clamps and a hotdog shape cooler with two compression fittings with oil lines.

Trust me you can't break anything here. Buy you can make a huge mess if you don't go slow.
 
PS. In the picture of your engine I am a bit concerned that I don't see a heat exchanger. If you don't have a heat exchanger that's not going to be good! Hence sand in your block. Not sure if you can get that out without a tear down.... start by pulling your thermostat and check if its plugged up if raw water cooling...

I hope there's a heat exchanger on your engines.
 
PS. In the picture of your engine I am a bit concerned that I don't see a heat exchanger. If you don't have a heat exchanger that's not going to be good! Hence sand in your block. Not sure if you can get that out without a tear down.... start by pulling your thermostat and check if its plugged up if raw water cooling...

I hope there's a heat exchanger on your engines.

You're not going to see heat exchangers on raw water cooled engines. So yeah...sand in the block would be a concern. I would think you could flush this, however.

I think this problem could be solved before full-on freak out. Clean the strainers, see if it still over heats. Check the impellors, see if it still over heats. Borrow t-stat from other motor, see if it still overheats.

If it still doesn't work after all of this I'd call a pro.
 
I believe you have Bravo III outdrives. So, in your case the water pickup is in the outdrive, no seacocks, no heat exchanger.

  • Start at the thermostat, pull the hoses and thermostat to see what things look like - make sure no sand is in/around thermostat.
  • Flush back towards the water pump - if you can pull the intake hose from the back of the water pump do that and verify flow - but it's hard to get to and be aware water is going to flood in once you remove the hose.
  • Pull the blue wingnut plugs on the manifolds see if sand comes out - leave them out while you are flushing things.
  • Flush water through the hoses that lead from thermostat house to manifolds - water will run out where you removed the blue plugs.
  • Pull hoses from the PS Cooler on back of engine - backflush PS cooler.
  • May end up replacing water pump impeller, but I would check everything else first since that is a bit of a PIA.

Sounds like a lot but it is not - really you are checking everything to see where / if sand and debris got sucked into the system and flush clean it out if it did. And possibly replacing the water pump impeller (sand could have damaged it) Not a whole lot different than replacing the thermostat and flushing the radiator in a car - if we are comparing.

That engine should NOT exceed 175deg the risers should never be too hot to touch, if they are then something is wrong - don't let it overheat!

Like others have said, if the above does not fix it or you are not comfortable doing the work, call a pro. I've worked on my boats for years, but one of the best tools I have is my wallet and knowing when to use it.
 
Thank you for all of the advice. I feel comfortable taking apart the cooling system and cleaning it. Is there anything that I should avoid doing so I don't get water into the cylinders? The system confuses me - are there two water pumps - one below the thermostat and one on the lower starboard side?
 
So the system has two water pumps, the raw water pump pulls seawater out of the lake/ocean. The circulating water pump is just like on a car, it circulates the coolant (seawater in this case) through the engine - the flow through the engine is controlled by the thermostat just like a car. The differences are this engine has no radiator, it uses the lake/ocean as the radiator and it has water cooled exhaust. The raw water pump pulls in sea water, the circulating pump and thermostat control how much of that seawater is circulated through the engine to cool it and then it goes through the exhaust manifolds and back into the lake/ocean.

When you ran up on the sandbar, you sucked in sand / mud /debris and either damaged the raw water pump or clogged something up - most likely the PS cooler or at the thermostat housing - you now are not getting enough flow from the raw water pump (think radiator) to properly cool the engine. So what you are doing now is the boat equivalent of flushing the radiator.
 
Pull your raw water pump out and take it apart on your bench. While it's off back flush from the furthest point back toward where the pump was. Take your garden hose and backflush the raw water pump hose that goes toward your drive.
 

Forum statistics

Threads
112,950
Messages
1,422,890
Members
60,933
Latest member
juliediane
Back
Top