2000 340 SD tracking water in bilge

Jessica Gardner

New Member
Aug 4, 2022
23
Louisville, KY
Boat Info
2000 Sea Ray 340 Sundancer
Engines
7.4 454 Mercruiser with V drives
I looked around before making this post. I found a few suggestions of where to start when tracking down a leak.. it seems to be a slow leak as when we wetvac the water out and watch for any moving water we cannot seem to see anything. But came back the next day and as soon as we stepped on the swim platform the bilge kicked on. While anchored in the cove it went off about 4-5 times in a 6
-7hour period.
I wasn’t sure if someone on here knows what a common issue might be to check first.
Just some back story. We bought the boat a couple of weeks ago. Never noticed this happening while at the slip looking at the boat for over an hour. Previous owner has paperwork of having the shaft seals replaced spring of 2021. We did have a 7 hour cruise down river to bring the boat home that something could have vibrated loose potentially and the water tank was empty on our way back, we filled it up the day after we got it back. It is still appearing full on the gauge after minimal use and a week and a half after filling.
My husband is a larger man and it is hard for him to maneuver in the engine bay so top suggestions on what to check first is helpful.
TIA!
 
I looked around before making this post. I found a few suggestions of where to start when tracking down a leak.. it seems to be a slow leak as when we wetvac the water out and watch for any moving water we cannot seem to see anything. But came back the next day and as soon as we stepped on the swim platform the bilge kicked on. While anchored in the cove it went off about 4-5 times in a 6
-7hour period.
I wasn’t sure if someone on here knows what a common issue might be to check first.
Just some back story. We bought the boat a couple of weeks ago. Never noticed this happening while at the slip looking at the boat for over an hour. Previous owner has paperwork of having the shaft seals replaced spring of 2021. We did have a 7 hour cruise down river to bring the boat home that something could have vibrated loose potentially and the water tank was empty on our way back, we filled it up the day after we got it back. It is still appearing full on the gauge after minimal use and a week and a half after filling.
My husband is a larger man and it is hard for him to maneuver in the engine bay so top suggestions on what to check first is helpful.
TIA!

first is to ID rain/seawater or water from the freshwater tank.

you could do it a couple ways - for the folks in salt (doesn’t look like you are) they taste it. For us freshwater boaters that usually means draining the water tank completely dry, or dying it.

since you said the level hasn’t dropped, and if the bilge pump is kicking on that many times in a a hour period I think you’d be down on water, it’s likely an external leak.

my favorite tool to trace the leaks are the blue “shop towel” paper towels from autozone. They show dark blue when they get wet so I laid them all over the engine room, wrapped around hoses, etc. Whichever ones get dark you can start to narrow the source

another common leak is your water heater relief valve. Again, you’d probably notice that much water coming out of the freshwater tank with the level dropping, but they sometimes stick open and will drain down into the bilge.

water leaks are a pain and it’s possible you have more than one. It’s an exercise in patience for sure.
 
What @Strecker25 said. It does sound like a leak in your engine compartment. Another way to rule out fresh water is to leave the freshwater pump turned off for 4 to 5 hours and see if the leak continues. It will be a process of elimination for you. The engine compartment has multiple sources for raw water, start learning where they are and tracing them.
 
One thing I didn't see suggested was rudder packing.
This was suggested to us as well by a few others, is this something that can be reached in the 340 with twin 7.4 very easily? I know the shaft seals are not simple to reach
 
I could reach them in my 1995 330da, very similar engine layout.. They're at the stern, in front of the motors, you'll see four bolts holding each in.
 
This was suggested to us as well by a few others, is this something that can be reached in the 340 with twin 7.4 very easily? I know the shaft seals are not simple to reach
You could try just tightening the nuts to see if that helps. Other wise, it's a job when you're on the hard.
 
You could try just tightening the nuts to see if that helps. Other wise, it's a job when you're on the hard.
We plan to do the blue rag trick starting tomorrow to see what we fine and also go through and tighten all fittings we can reach since we did take that 7 hour cruise and there was some drift in the river that we bumped a few times. Hoping to leak isn’t anything we will have to have the boat pulled out of the water for but, our fingers are crossed we can atleast locate it and go from there
 
We plan to do the blue rag trick starting tomorrow to see what we fine and also go through and tighten all fittings we can reach since we did take that 7 hour cruise and there was some drift in the river that we bumped a few times. Hoping to leak isn’t anything we will have to have the boat pulled out of the water for but, our fingers are crossed we can atleast locate it and go from there

Would be helpful to know where the water is and where it isn't. For example, do you have water in the bilge areas, forward of the exhaust downpipes, between the outboard engine stringers and the side bulkheads. I'll see if I can find a picture
 
Would be helpful to know where the water is and where it isn't. For example, do you have water in the bilge areas, forward of the exhaust downpipes, between the outboard engine stringers and the side bulkheads. I'll see if I can find a picture

This is looking down and astern. You've got bilge areas running fore and aft on the outside and inside of each engine along the stringers. If you follow the green arrows toward the stern the rudder posts are back there (out of frame in this picture). You've got upper bilge areas around the posts that drain down into the main sump. If it's wet up there, it's probably a rudder post, unless you've got water leaking down from the transom shower connection for example.

The main bilge sump is in the area of the red box, where your main and emergency bilge pumps are.

While the water ultimately will collect in the sump, it's helpful to know whether the areas depicted by the red arrows are dry or wet. If dry, the water is coming from someplace further aft. Perhaps rudder posts.

The water heater is on the port side (which would be to the right in this picture because we're looking aft) toward the forward bulkhead. If you've got a bunch of water over there, that would suggest the water heater. Your water pump will be on the stbd side on the forward bulkhead. The feed from the water tank comes through the bulkhead at the bottom and up to the water pump. You've got water lines that then go across the bottom of the bulkhead to the port side. From there they go to the water heater, up to the cockpit icemaker and sink, aft along the red arrow on the right of the picture to the transom shower and water inlet.

If you dry out the side bilges and vac out the sump, sit in there with a flashlight and just watch. Inevitably, you'll see a trickle of water coming from somewhere.

It can be a frustrating and time consuming process.


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Great news! I found it (myself!!, yes female ) it is a cracked raw water pump housing on the starboard engine. Which we already planned on replacing on both engines and have one on the boat and will be replacing it this weekend! Once we replace that I’ll suck up all the water and make sure there is nothing else
 
Great news! I found it (myself!!, yes female ) it is a cracked raw water pump housing on the starboard engine. Which we already planned on replacing on both engines and have one on the boat and will be replacing it this weekend! Once we replace that I’ll suck up all the water and make sure there is nothing else
 

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