Black Water Holding Tank Leaking

sdleo26

sdleo26

Member
Feb 5, 2011
526
Long Island, NY
Boat Info
290 Amberjack 2004
Engines
350 5.7 MAG MPI Horizons w/ V-drives
I have a 2004 290 Amberjack. It has a Sealand Vacuflush head system (40 HTS) which is common on SR's as you may know. I hardly ever use it, thank god!! Much to my surprise, it started leaking out of the aft starboard corner; at the underside no less (surface mounted to bilge floor). The Tank is mounted on the port side of the boat, as I have a gen-set on the starboard side. The manual clearly states there are no, I repeat; no tappings or drillings below the water line. Upon taking apart the hoses and mounting hardware; tilting tank up to look at the bottom, there were 4 mounting screws/bolts in each corner (flat head allen hardware). Sure enough, the corner that was leaking had a rusted (not even stainless WTF) screw. I used epoxy on not only the corner that was leaking, but the other three as well. The other three appeared to have rust, but not leaking. When I called Sealand Dometic, they claim that these are for mounting and are "molded" in the tank. I am not sure where there would be an application to mount these tanks from the bottom! Be that as it may, they leak over time, BEWARE!!! I was wondering is anyone else has run into this before? The patch job seems to be working, but what a poor design to say the least!! Good luck getting to mounting hardware if you this happens to you. It is not impossible, but take a whole lot of patience, chinese finger, mirror and the right length drivers.
 
Yes, had the exact same thing happen to mine. From what I understand, those "mounting hardware" pieces that you found on the bottom side are for the mold-process when the tank is being made - sort of a way to hold the tank while it is being molded. They are not supposed to intrude into the interior, but apparently some have done that and over time have cracked/split. I replaced my whole tank as I only wanted to mess with this once. FYI, I only needed to remove the two inboard screws/thimbles to remove my tank and it was actually a pretty easy process but I also have a very user-friendly bilge.
 
Thanks for replying. Removing the tank and replacing was not an option unfortunately; otherwise I would have replaced it as well. The only way is to pull motor (not happening) or cut tank up and tank out, then replace with smaller tank. I hope the JB weld epoxy holds.

Scott
 
sdleo26 said:
I hope the JB weld epoxy holds.

Scott
Click to expand...

I hope, for your sake, it does, too! Polyethylene is one of the hardest substances to glue - the only way to even have a chance of making it permanent is to first flame-treat it. Other than that, it's a crap shoot........
 
I had the exact same thing happened. I was able to pull the tank and apply a generous amount of silicone to all 4 holes. So far so good. 2 months of use and all is well.
 
I used a puddy epoxy, hardened like steel.. Been 3 weeks and holding. Keeping my fingers crossed!!
 
Just purchased my "new to me" 2002 340 sundancer with the same Sealand setup and was wondering why the tank monitor never registered even 1/4 full. My first thought was that the sensors had corrosion like I found in many other places on this boat, but just discovered this afternoon after putting the blue stuff in the tank that I now have a blue stream in the bilge. Apparently all the fluid has been leaking out of the tank as it goes in and that is why the tank monitoring doesn't register! I started getting suspicious last weekend (the first weekend my wife and I stayed on the boat) after a sewer smell became present. I had never heard of a plastic holding tank leaking! So, please clarify, as I have not yet started tearing into this. Are there mounting screws under the tank that rust? How do these intrude into the tank? Are they already through the tank? Why would Sealand put holes in the bottom of a holding tank??? The 340 with 8.1s is damn near impossible to work on to start, so trying to replace this tank looks to be an impossibility without pulling the port engine! (or as someone stated earlier to cut up the tank and replace with a smaller one.) What products has everyone used to seal the holes? Are there any products as there are for radiators that you put in the tank and it would "self seal"? ( I know that is wishful thinking!) Any further advise is welcome!Rob
 
Rob - There is indeed hardware that protrudes thru the bottom of the tank. I called Sealand and confirmed; they claim that there are "mounting" screws located in each corner, but do not go into tank; obviously they do, as we all have this leak. I used a J&B weld putty epoxy. I got it at lowes, you can apply to wet surfaces, under water etc... Another victim used silicone (posted on this thread). Mine has been holding for over a month, with no signs of leaking. I recommend tying the tank up and applying epoxy to each of the four corners. Good luck, it is in a rough spot for sure, but it can be done. It's definitely worth a try before you replace with smaller tank. Let us know how you make out

Scott
 
That Stinks! I agree on the marine putty or underwater epoxy repair cement, Mike.
 
Hey guys , can't believe I'm reading this post right now. Was. At the boat today trying to figure out why I sometimes have dirty water in my bilge. Said to my self it can't be this sealed plastic box it has to be coming from someplace else. Have twin 4.3s looks like I can get in there to change it , are there any special tips or tools that I would need. Thanks again tony.
 
If you have the room to change it, you are ahead if the game... now just hold your breath and get a pair of gloves!!!
 
Scott
Thanks, I will start pulling everything lose to gain access to the bottom. Hopefully I can remove the tank by removing the mounts inward of the engine compartment because I cannot even see the outside mounting. I will update as I get started on this.

Rob

sdleo26 said:
Rob - There is indeed hardware that protrudes thru the bottom of the tank. I called Sealand and confirmed; they claim that there are "mounting" screws located in each corner, but do not go into tank; obviously they do, as we all have this leak. I used a J&B weld putty epoxy. I got it at lowes, you can apply to wet surfaces, under water etc... Another victim used silicone (posted on this thread). Mine has been holding for over a month, with no signs of leaking. I recommend tying the tank up and applying epoxy to each of the four corners. Good luck, it is in a rough spot for sure, but it can be done. It's definitely worth a try before you replace with smaller tank. Let us know how you make out

Scott
Click to expand...
 
Well, the job is done....or at least I hope so! This past Saturday I was able to remove the mounting screws holding the tank and confirm that it was in fact leaking on the rear outside corner where the mounting hardware was imbedded in the bottom of the tank. I obviously needed to take a garden hose into the bilge and do some major cleaning prior to doing the repairs. I had to remove the mounting hardware on the hot water tank as well so I could move it forward to allow me to move the holding tank forward enough to clear the muffler so that it could be turned. Unfortunately, the high section of the tank still did not allow me to turn it completely over in place, but I was able to get to the fittings. Like Scott, I used the JB Weld Epoxy and did all four corners while I was under there even though it appeared only one was leaking. This project took the best part of the day to complete, but as of Sunday night after a day out on the water, no leaks detected. I believe if the patch fails, I will replace with a smaller tank and one from a manufacturer that doesn't sabotage the product from the beginnning!
Rob
 
Thanks to everyone posting regarding this topic.

For anyone with a 300 Sundancer from 2002 to 2007, I just worked with a friend of mine to remove the holding tank. I thought that I would have to remove the outer riser of the port engine, but my buddy figured out a way to remove the tank by removing the head pump and lowering the fresh water manifold (with all the blue and red hoses attached).

Also, there are 6 mounting screws/inserts, 4 of which have to be removed, and the 2 towards the stern of the bilge (when facing the tank they are the ones on the left side of the tank) are VERY hard to remove. The 2 that at the port bulkhead of the bilge can remain in place. There are brass inserts that allow the tank to slide out. I had seen many posts stating that there were only 2 in front that had to be removed. I just wanted to warn anyone doing this job that those 2 screws/inserts on the left side of the tank are the hardest part of the job.

I have yet to finish the job, but just wanted to share this just in case anyone was thinking about attempting this job this season. To me, the greatest victory was not having to remove the elbow and riser of the port engine. I'm sure that it's not hard to do, but I don't like disturbing things that are not having issues.

Btw, to remove the screws it helps to have a 10 in and 6 in extender for your ratchet.

Hope this helps future holding tank repairs.

Eddie
703-626-7625
 
I misspoke in the number of screws/inserts - there are 8, 6 of which need to be removed; all but the rear 2 screws/inserts towards the port bulkhead.
 
Update...two years later, I am replacing the entire tank that I attempted to patch. Although I haven't found a visible leak, the bilge does not smell right. I am guessing it is leaking under the tank and any visible stream is vaporizing in the heat. I have ordered the complete replacement from West Marine with all equipment already installed for about 1,100. Not cheap, but the tank alone was $780 without the pump, monitor, filter, or fittings, so it seemed to make sense to me to get the complete unit for a few hundred more. Will keep you posted how this replacement goes!
Rob
 
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