General Info: Seawater in the bilge

[faa50]

This morning after draining the bilge box, I ran the starboard engine for 30 minutes. Revisiting the bilge box roughly 3 inches of water accumulated in the bilge box. I also saw a small amount of what I suppose to be
seawater on the bottom of the engine compartment directly beneath the limber hole. These observations seem to confirm the leak is originating from the engine room and most likely the engine itself.

Once the engine cools down, thinking the first place to examine is the sea water pump, its mechanical seal and the impeller.

Being first time boat owners we are learning a lot which we expected. The positive comments and suggestions made by CF members are assisting us in the learning curve. Thanks to those of you willing to help a newbie boat owner and fellow sailor in growing his experience curve.

[faa50]

Going ashore this morning I met with two Yanmar professionals, distributors, who are confident the issue resides with the seawater pump. The pump has a lip seal which I'm told has a tendency to score the shaft. In additional there are 4 or 5 mechanical seals including seals on both sides of the impeller. I could service the old unit but I'm told it will probably last two - three weeks before leaking again due to the scored shaft.

The Yanmar mechanics advise to replace the entire seawater pump and rebuild the old unit so as to have as a spare (the boat has two engines which means two seawater pumps.) The other unit was replaced prior to my purchase of the boat.

Sea water pump is ordered from Florida and we plan for a Yanmar mechanic to install on Wednesday of next week.

[DavefromNZ]

Faa50. Sorry I don't wish to seem harsh but seriously you need to take some time to understand your yacht. The first thing you should have done is close the valves that drain water from the for and aft compartments. You would have immediately seen it was coming from the eng compartment. Did you taste the water in the eng compartment that was just below the hose outlet?

Then spend time figuring out where the leak is around the engine. Simply follow the 'raw' water (sea water) pipe flow. It is not a difficult job however I would suggest now that you should get a professional to do this.

I just re-read your last post. It appears you have not actually seen that the leak is from the impeller pump area and are just going on a mechanics opinion? I service my Yanmar engines. The impeller simply runs on a shaft and there is one seal for the cover. Is the leak here? It will be obvious. Have you dried carefully all the connectors in the sea water system to see it they are leaking?



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[DavefromNZ]

It is also possible that sea water is coming in through the sail drive to hull diaphragm. These are not inspected or replaced as often as Yanmar suggests we should all do. As your leak occurs when the yacht is moving and not necessarily when the engine is running then this should be checked.

Water in the eng compartment could only come from

• Sea water from raw coolant system or sail drive diaphragm.
• 'fresh' water coolant - will be red or green coloured.
• eberspacher heater coolant - will be coloured.
• fresh water - if you have pipes in compartment, say for outside shower on stern.

I would suggest ordering a pump without ascertaining that it was the problem first may be a slow and expensive way to solve the problem. Observation would be the better way :-)

[PaulinOz]

"I would suggest ordering a pump without ascertaining that it was the problem first may be a slow and expensive way to solve the problem. Observation would be the better way :-)"

Dave speaks the truth here. Observation would be the better way

Most Yanmar raw water pumps have one shaft seal and one o-ring as a front plate seal.

Moor common than your multiple faulty mechanical seals and scored shaft is a lose or split hose attached to said pump or inlet valve, have these been inspected first.

This could be as simple a lose hose clamp that just requires tightening. Eyeball 101 the best diagnostic tool we have. Having some one replace the pump may well fix the problem, but was it a faulty pump or will they just tightened up the hose clamp after re fitting a new pump.

[faa50]

For those curious as to the final outcome.....

After narrowing down the persistent leak's location to the starboard engine and its seawater pump as noted by the water exiting the pump, rust stains, large engine catch basin beneath engine full of seawater, ect, a new seawater pump is installed. No more leak!!!! Bilge is bone dry. To validate - A Memorial weekend round trip sail to St. Barts - Anse de Colmbier and 10 hrs run time on the engine after repair and status remains the same.

Disassembling the seawater pump, the outer o ring is in tack and not damaged. The impellar is also serviceable. The shaft is scored and allows water to leak around the inner seals. Root cause is typically a seawater's V belt being "over tensioned.

FYI for those of you with a 3YM30 engine....
While installing a new seawater pump, we discovered the starter side front engine mount is broken.

Yanmar dealer acknowledged that they are seeing a number of Lagoons with this engine and mount failing. Seems that the 100s hard rubber vibration mount are not sufficient for the torque produced on this side of the engine. We replaced with a 150 and do not expect further issues from this location. That still leaves three starter mount feet that might need replacing. Will monitor the situation.

Fair winds to all those who assisted in the discover process...

[Cadence]

Originally Posted by faa50

For those curious as to the final outcome.....

After narrowing down the persistent leak's location to the starboard engine and its seawater pump as noted by the water exiting the pump, rust stains, large engine catch basin beneath engine full of seawater, ect, a new seawater pump is installed. No more leak!!!! Bilge is bone dry. To validate - A Memorial weekend round trip sail to St. Barts - Anse de Colmbier and 10 hrs run time on the engine after repair and status remains the same.

Disassembling the seawater pump, the outer o ring is in tack and not damaged. The impellar is also serviceable. The shaft is scored and allows water to leak around the inner seals. Root cause is typically a seawater's V belt being "over tensioned.

FYI for those of you with a 3YM30 engine....
While installing a new seawater pump, we discovered the starter side front engine mount is broken.

Yanmar dealer acknowledged that they are seeing a number of Lagoons with this engine and mount failing. Seems that the 100s hard rubber vibration mount are not sufficient for the torque produced on this side of the engine. We replaced with a 150 and do not expect further issues from this location. That still leaves three starter mount feet that might need replacing. Will monitor the situation.

Fair winds to all those who assisted in the discover process...

Grats! Thanks for the feedback.

[Mardi Gras]

Congrats on discovering your leak. I own the same year and model and will be inspecting my engine mounts. Thanks for the tip.

Tony
S/V Mardi Gras

[LoudMusic]

Originally Posted by faa50

For those curious as to the final outcome.....

After narrowing down the persistent leak's location to the starboard engine and its seawater pump as noted by the water exiting the pump, rust stains, large engine catch basin beneath engine full of seawater, ect, a new seawater pump is installed. No more leak!!!! Bilge is bone dry. To validate - A Memorial weekend round trip sail to St. Barts - Anse de Colmbier and 10 hrs run time on the engine after repair and status remains the same.

Disassembling the seawater pump, the outer o ring is in tack and not damaged. The impellar is also serviceable. The shaft is scored and allows water to leak around the inner seals. Root cause is typically a seawater's V belt being "over tensioned.

FYI for those of you with a 3YM30 engine....
While installing a new seawater pump, we discovered the starter side front engine mount is broken.

Yanmar dealer acknowledged that they are seeing a number of Lagoons with this engine and mount failing. Seems that the 100s hard rubber vibration mount are not sufficient for the torque produced on this side of the engine. We replaced with a 150 and do not expect further issues from this location. That still leaves three starter mount feet that might need replacing. Will monitor the situation.

Fair winds to all those who assisted in the discover process...

It's always great when someone comes back and reports their final results. Cheers!