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Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10977
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I have a 2005 SeaRay 320. Bought it 2 years ago. Did a

Customer Question

Hi! I have a 2005 SeaRay 320. Bought it 2 years ago. Did a lot of improvements in the engine compartment, but the GenSet run well so did not do anything other than service. Always ran well until one day after a long trip it would not start. Clicked but did not turn over. Called the mechanic who looked in detail and said that salt water got into it. Ended up getting a new (remanufactured) GenSet. All is good, but I wonder what caused the problem to begin with so it does not happen again. I do have a syphon break installed, and it was there in the old unit. I could close the seacock while underway, but I think that's not where the water could come in from. I've read about the muffler flap being stuck, but don't know how to check. Any pointers for what I could double check to make sure the problem does not happen again?
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.
Hello. My name is ***** ***** comes in through the exhaust if the siphon break is clogged or stuck. Be sure it is clear and functions correctly. What happens is when you are running the boat if no siphon break the genset will start to siphon water through the cooling system and when the water gets to the exhaust where the water exits the heat exchanger it is sucked backwards in through the exhaust causing the engine to flood. With the siphon break it will not start the siphoning action. For installations where the exhaust manifold/water injected exhaust elbow is close toor will be below the vessel’s waterline, provisions must be made to install a siphonbreakin the raw water supply hose to the exhaust elbow. This hose must be looped aminimum of 20” above the vessel’s waterline. Failure to use a siphon-break whenthe exhaust manifold injection port is at or below the load waterline will result inraw water damage to the engine and possible flooding of the boat.If you have any doubt about the position of the water-injected exhaust elbow relativeto the vessel’s waterline under the vessel’s various operating conditions, install asiphon-break.NOTE: A siphon-break requires periodic inspection and cleaning to ensure properoperation. Failure to properly maintain a siphon-break can result in catastrophicengine damage. Consult the siphon-break manufacturer for proper maintenance.
Customer: replied 1 year ago.
Thanks for the detailed reply. I did have a siphon break, but I did not check to make sure it was working properly when we checked in the engine. I installed a new siphon break when we replaced the GenSet. I'll be sure to check on it when I check seacocks. A follow-up question . . . Would closing the GenSet seacock while underway help? I guess it would, right? Also, I read about making sure that the the thruhull opening does not have a scoop like is needed for engine or A/C seacocks, is that right? Thanks!
Expert:  Tan replied 1 year ago.
Correct on both. Closing seacock and no scoop.The issue with closing the seacock is if you forget to turn it on before starting the gen set you will toast the pump. You can make a note at the start up switch to turn seacock on. You will usually only forget once.

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