Water leak in 2018 520L

[Dr.Spook]

Over the last month I've noticed my bilge pump turning on and emptying water for a short while(2-3 Minutes) in my 2018 520L boat about every 20 minutes. It starts up right after my boat is backed into the water while still on the trailer. I decided to see where the water was coming from by removing the rear splash well cover at the transom and removing the plate inside the battery compartment to view the bilge area. No water appeared to be coming from any of the inlets coming from equipment mounted through the transom including the drain plug, however water was coming up through the open outlet plug at the rear of the transom splash well spilling into the hull, especially when the boat was moving. This water would fill up the splash well like an artesian well and drain into the bilge and trigger the auto bilge pump. I ended up plugging the top outlet with a 1 inch drain plug and this stopped the water coming up through it. The bilge is still taking in a small amount of water, the bilge is coming on, but stopping within 2 minutes when my boat is first launched, especially on steeper ramps. It still pumps occasionally while on the water, but it is way better now with the drain plug in.

My question is, the plug opening in the top of the splash well is connected through a hose that runs to the plug opening on the bottom of the setback of the hull. I would think that would constantly siphon water up to the splash well when the boat is moving or with wave action like it was doing before I put the plug on the top plug hole. Is there supposed to be a valve in the hose to prevent a back flow and is it supposed to be plugged? Has anyone else experienced this? Anything else I'm missing here?
Thanks!

[jc2bg]

It’s not normal for these boats to take on water [of any significant or constant amount], but when they do, there can be several causes. As much as you probably do not want to hear this, I doubt you have found your main or initial water-intake problem by plugging the splashwell vent hole. Unless the boat is in constant and significant wave action, the splashwell does not take on enough water to run into the bilge. And when the splashwell is fully flooded, the only place that water should be getting into the bilge is through the rigging hole. At a really steep ramp, this also can happen, but once you pull away from the ramp the auto bilge should take care of the water and not continue to run, as yours does.

My $.02: you have another small leak somewhere, very likely somewhere difficult to see [like 99% of stuff down in the bottom of the bilge]. Could be a leaky livewell controller [the little plastic box that your livewell linkage connects to] or any of the livewell fittings. Unless you constantly have the livewell set on “recirc,” water is flooding all those fittings even when the livewell pumps are not running. Could be somewhere else, too, but detective work of various kinds would have to be employed.

[Dr.Spook]

Thanks for your input. I have observed these areas you mentioned and have not seen any water coming in around them. What would cause the water to come up through the drain in the splash well, from the drain in the transom extension on the bottom with drainage into the bilge like a fountain when the boat is moving?
I do keep the livewell setting on recirc when not using it and in checking the leak, I filled the livewells and ran the pumps and did not observe any water leakage. All fittings were completely dry. Like I said, plugging that splash well drain opening took care of 95% of the leakage issue.

[jc2bg]

I am confused about the fountain of water you mention, and also about how the same water gets into the bilge. Do you have the splashwell access cover removed when observing this phenomenon? That’s the only way, other than extreme amounts of water pouring through the rigging hole, I can imagine splashwell water getting into the bilge, because the splashwell vent tube is a 1-way system. It’s open at the top and open below the stern—just one long tube that doesn’t go into the bilge, unless that tube itself has a leak? Anything is possible, and most of it has happened to me. But your situation is a new one in my experience, if the splashwell vent tube is in fact leaking. I will also confess that I have never looked back into the splashwell while the boat is under way, but definitely can assure you that if a fountain of water comes up through that tube, it typically disperses without causing the bilge pump/s to run. Good luck! This one is a mystery.

[Dr.Spook]

I assume the water is coming up that tube into the splash well and through or around the splash well cover. No water is apparent leaking out the tubing either. If it continues, I will check with a dealer. I assume it is covered by the warranty?

[jc2bg]

Definitely covered by warranty. Random thought: is it possible that a jack plate or power pole/talon mount is scooping excessive water into your splashwell? No matter how it mysteriously gets into your bilge, you should not be getting a fountain when under way. And of course when on plane, the bottom of that tube is out of the water.

[gsb0824]

I had the exact same problem with the exact same boat. It was very frustrating. Look in your splash well and look to see where the transom motor bolt plastic covers are. If they are mounted so low the bottom part of these covers cover the crease between the transom and the splash well, that is your problem. That was my problem. And it is not easy to fix. If this is your problem, let me know and I can explain how to repair or what to tell your dealer if you want them to repair under warranty.

[jstbass]

How about thus as a cause. If you have removed the splash well cover I believe that there is a seal of RTV around the cover from the factory. Once you remove the well cover plate you might have broken that seal allowing water intrusion into bilge area. Might be something to consider.IMO???????? I also have the same model boat and notice the cranking battery tray was filled with water the other day. Please let us know what you find out.

[Dr.Spook]

I will check on the transom bolts and let you know. There is no seal that I noticed under the splash well cover and I’ve had to remove it to access the Power Pole pumps when they had a problem.

[jc2bg]

Water will definitely drip into the bilge through the splash well access cover if the seal is broken/disturbed. I did not mention this as a cause of leakage because the OP said he had a leak before he opened that cover. Plus he also said that the leak diminished when he plugged the vent tube. However, the access cover might have been removed more than once. It should be siliconed to eliminate future leakage.

[Dr.Spook]

The plastic cover on the starboard transom bolt is in that crease and the port side is just touching it. Also, when I removed the splash we’ll cover for the first time there was no evidence of any seal put on under it. The bottom screws do not fit tight as it would take a lot of silicone to seal that area. What is the fix you mentioned for this?

[gsb0824]

The plastic cover on the starboard transom bolt is in that crease and the port side is just touching it. Also, when I removed the splash we’ll cover for the first time there was no evidence of any seal put on under it. The bottom screws do not fit tight as it would take a lot of silicone to seal that area. What is the fix you mentioned for this?

If the bolt hole covers are in the crease, they are not watertight and will leak. The bolt hole covers are only in the crease on some of the boats, not all of them. Why Ranger doesn't do a quality check on this I have no idea. My dealer epoxied two small wooden boards to the backside of these holes from the inside. He used some type of marine sealant on them as well. It was sort of a homemade remedy, but it worked. My dealer also resealed the splash well cover. This fixed my problem.

[Dr.Spook]

Thanks for that information! Hopefully keeping a plug in the splash well will keep the leak in check other than when waves splash into that area. I will contact a dealer if it gets worse.

[Ranger519VS]

There shouldn't be a fountain spraying up thru the splashwell drain while under way as the hole on the underside is out of the water while on plane. I will say that I had a leak in the splashwell drain on a Z21 (or was it my Z521?), doesn't matter. The drain consists of two thru wall fittings and a hose in the middle. One of the hose clamps was loose, or missing in my case and the drain would leak.

[jimsch]

What about the rub rail?

[jc2bg]

There shouldn't be a fountain spraying up thru the splashwell drain while under way as the hole on the underside is out of the water while on plane. I will say that I had a leak in the splashwell drain on a Z21 (or was it my Z521?), doesn't matter. The drain consists of two thru wall fittings and a hose in the middle. One of the hose clamps was loose, or missing in my case and the drain would leak.

Never thought about that one, Butch, but it does fit with the symptoms. Another possibility for taking on water is the remote bilge plug, as they occasionally don’t get fully seated or have an O-ring dry out/crack. That possibility doesn’t fit his symptoms quite as well, however.

[Dr.Spook]

When I removed the splash well cover again I saw where the rubber seal was separating from the plastic along the stern edge and sides. I glued it back down and put silicone seal all the way around the stern and side edges. I’m sure that’s where the water is getting through from the splash well itself.

[jc2bg]

When I removed the splash well cover again I saw where the rubber seal was separating from the plastic along the stern edge and sides. I glued it back down and put silicone seal all the way around the stern and side edges. I’m sure that’s where the water is getting through from the splash well itself.

Good to know.

[CaymasRodney]

Nine times out of ten the splash well cover is the leak, the other 1% is usually a cracked live well pump, just a hair line crack get lots of water in your bilge.

[Dr.Spook]

After running the boat yesterday, it was much better with the splash well drain plugged and seal repaired. My lower cover screws are almost all stripped so I'll have to replace those with something bigger to get the plate to seal better.
Thanks for the input everyone!