View Full Version : Outback LS - plumbing in factory tank

04-14-2008, 01:43 PM
Hi all,

New to the forum, just picked up my first Moomba, a super clean 03 Outback LS with 130 hours on it. It has the factory ballast tank under the rear seat, but it is not hooked up yet from factory.

Looking for information on what i need to buy and how to make this work. I'm pretty handy to do it myself just need to know exactly how this should be setup. I'm assuming the pump has to be tapped inline with the factory water intake or do I actually have to cut a new hole in the bottom?? :o BTW there is three inlets on the tank, two on top (fill?) and one on the bottom (drain?)

Any help would be appreciated!

04-14-2008, 07:18 PM
Hi Stuey,

Welcome to the forum. On my 2006 LSV, there is a separate intake for the ballast. And the bag fills from the top and drains from the bottom, just like you wrote. The other top hole is for venting air out of the bag.

My suggestion would be to look at another boat with a factory plumbed ballast system for reference. If you are close to a Moomba dealer, that would be the best place to go.

Hope that helps.


04-15-2008, 06:30 PM
Well, I can tell you how my 2001 factory tanks were plumbed and that may help some. Now, mine had two tanks, and they were in the back ski locker, so it is a little bit different. First, there is a 2000gph Rule areator pump mounted through the transom between the exhaust outlets. Make sure you have enough room for the rudder mechanism. This pump was plumbed with, I think 1", clear reinforced flexible hose (you can buy it at Lowe's or Home Depot, it is the clear stuff with the whitish fibers crosshatching it). Next there was a "tee" fitting that fed into the top of both the tanks. This allowed both tanks to fill at one time from one switch. There was also a smaller line, a 3/4" I think, from the top of each of the tanks that connect together and feed out the side of the boat for vents to let air escape from the tanks as they fill, and air to enter as they empty. For the drains, there were two more Rule areator pumps (750 gph each) mounted into the bottom of the two tanks with a 3/4" line running from them to two more through hull fittings. These were switched separately so the ballast could be balanced (in theory). It worked fine and I never had any trouble with it, it was only 350 pounds though and I wanted more. Also, the boat has to be sitting still to fill the tanks because the way the pump inlet is pointed backwards, the pump will not prime while moving. I ripped all of that stuff out and redid the system. I reused the 2000gph pump in the factory location, but it is now feeding into the top of a 750# fat sac. I also plumbed a vent line into the new sac that connects to one of the previous vent through hull fitting. Next I took one of the 750 gph pumps and plumbed it into the bottom fitting on the fat sac for a drain pump. I routed it using another "tee" fitting to both of the factory drain fittings. This way, none of my through hull fittings just dump into the boat, and when I drain the sac, the water still comes out both sides. It is no faster, but it looks cooler. Now I can still use the factory switch to fill and empty the sac. Now I ran into a few issues with this new system. First, the sac is too large for the compartment and we have to keep an eye on it while filling to make sure it doesn't get twisted up or too full. If it is overfilled, it starts to lift up the ski locker lid. I figure I get about 650# in it and since that is almost twice the factory, I am happy, although loosing the storage is kind of a pain. Next, I had to put a manual valve on the vent line because the vent line is lower than the top of the bag, and there is no good way to raise it up. So the valve stays open for venting until water starts coming out of it, then we close the valve and fill the bag up the rest of the way. The other problem I noticed was that when the bag was full, water was coming out of the drain fittings. I assumed that because of the increased water capacity, that the "head pressure" of the water was too high for the drain pump and the water was coming through even when the pump was off. So to remedy this, I just put another manual valve on the drainline. So now, when I drain the sac, I just have to reach down and turn the lever, and then flip the switch. It is slightly more effort than the factory system, but well worth the effort. The only things I would like to change would be to get a custom sac made to fit the locker better, and a larger drain pump. With the 2000 gph pump, it fills rather quickly, but the 750 gph pump, it is much slower to drain. I hope this helps some.

04-18-2008, 11:17 PM
I'm finishing this exact project this week on my '03 outback LS. I made a fitting that goes into my drain with a valve for the inlet (no new holes and didn't have to cut intake) on top of the valve is a quick release fitting so it acts as my regular plug then when i want water i can hook on my pump and turn the valve (figured a turn off was a good idea!) ran that to a pump to the top left of the tank, used the middle of the tank as a vent and hooked a second pump to the bottom for the drain. I just put in two thru hull fittings on the back driver side of the boat for the vent and drain. i bought the pumps at a local west marine and all the hose, clamps and fittings from tru value. hope this helps.

04-19-2008, 12:20 AM
Wow North Carolina State U. Do they not have paragraphs there!? :lol:

04-21-2008, 10:32 AM
I'm beginning to see how this all works.. what type of pumps do you guys recommend and where's the best place to get them (online preferred)