Replacing Sea Water Pump when Boat is in the Water

4sure

4sure

Member
Feb 16, 2008
86
Norwalk, CT
Boat Info
360 Sundancer 2002
Engines
Twin 8.1L Mercruisers
Are there any issues with changing a sea water pump when the boat is in the water? Will water gush from the hose between the pump and the Bravo III ? I checked the Merc 454 manual and it does not have any warnings about it. I changed one before however I could not remember if the boat was in the water.
 
Does the Bravo have a separate raw water pump like an inboard? If so you must have a seacock on a thru hull fitting for suction and it must be closed (I just did mine yesterday). It is my understanding that the Bravo water pump is in the drive and that there is no way to change it while it's in the water.:huh:
 
The water pump is on the engine. The intake is on the Bravo III. I am concerned water will gush in when I remove the hoses from the back of the pump. One hose is from the bravo III the other goes to the engine. There is no shutoff.
 
OK...you are changing the circulating pump on the engine...not the raw water pump in the drive.

I have never done one in the water with I/O's. I think it would be ok but to be safe talk to an I/O mechanic familiar with how this rig is plumed. Is there no info in the manual?
 
I am changing the raw water pump, not the circulating pump. On my Bravo III the raw water pump is mounted on the engine. My concern is the pump is below the water line and water will enter the boat through the hose from the Bravo III cooling ports.
 
I just found a blurb about plugging up the sea water side of the pump when flushing with fresh water. Why the warning is not with pump replacement, I will never understand! Thanks for the assistance Sprink56 !
 
Since I have the same boat I think I can answer you correctly - The raw water hose from the transom IS BELOW the water line on our boats!. I made a plastic plug to put in the hose (1 1/4") originally but now I have installed a flushing system with a shut off valve. If you just hold the hose up it will stop pouring water into the bilge. It will leak water into the bilge when you connect it onto the new pump and pull it off the old pump, but not fast enough to worry about. The hose is so stiff it may be a pain to route up high enough, so the plug makes it easier IMO.

Hope this helps. BTW - great boat!
 
You are right, the hose is very stiff. I did the job out of the water once. I never did it in the slip. Thanks for the dimension of the hose, it makes it easier to get a plug. I appreciate the assistance!
 
I believe the hose end will be higher than the water level when you remove it from the pump. So, no water should come it. I replaced my pump last summer and when I went to a dealer to get a rebuild kit they said the pump has been upgraded and the rebuild kit is a full new pump. Both ends on my old pump came off when all the bolts were removed. The new pump has one end molded to the side casing making it a better design.

Hope this helps. JD
 
Bravo drives do not have a pump in the drive. As stated it will be close to the water line and you should be prepared for lots of water from the intake hose. I just changed mine out of the water and it was difficult but doable. I lubed hoses with dish soap and heated with a hair drier to make it easier to put them back on. Also lubed impeller with the soap to avoid a dry first start.
 
I just changed mine (out of water), For mine, they don't mention anything - no warnings or other bold-face notes about the safety issue.

I would think the boat would need to be out of the water.
 
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I have done this in the water twice. This is the reason I made a plug on the lathe at work. It is not that I could'nt stop the water flow, (lifting the hose up) but if you put a plug in, you could let trhe hose fall to the bilge and not worry while you pull the pump.
 
Should be no problem. just plug the hose, they is very little pressure. When I work in the bilge I try to have someone on deck that can assist me
 
I have to do this in the water also. My plan is to put muffs on the drive with a garden hose above the water line pull the raw water hose off and plug it with a tapered wood dowel. This should minimize or stop the incoming water. Better then pulling her out of the water!
 
its far below the waterline and you will sink if you disconnect the quick connectors on that red hose going to the pump and cannot block the end which is connected to the water pickup in the transom.

other way : hold the end of the red hose up above the waterline

best
 
Update I used muffs to block the inlet holes on drives with garden hose above waterline. Drained motors pulled pumps with min. Water leaking.
Used wood plugs to plug the inlet just in case!
Worked great and stress free!
 
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