I have a 02 31 sonic with twin 496 ho engines. Ikeep finding water in the bilge after using boat for the day and letting it sit over nite. I have ruled out any leaks from out side of boat because it has new bellows etc. . if I suck out any water in bilge with shop vacuum and not run engines the bilge is bone dry the next day. but if I run the engines for half hr or so and look in bilge there is no sign of a obvious leak? if I come down the next day and check the bilge will have 1-2 gallons of water? I can run this experiment over and over with same results any ideas where this leak could be coming from in the closed water system or is it something else?

air actuators drains and especially if the boat was in salt water and or gritty and or brackish waters.

bup where are these air actuators drains located and how many are there ? boat is fresh water only.

509 sc I'm thinking you exactly right and this is my leak!!! I just have to trace them out and check hopefully I can get to them to check alittle tight in the bilge with twins!!!

they are junk over time. Higher water pressures while running can make them leak as well. Man back in 2001 we filmed in the engine compartment a boat that NO ONE could ever find its water leaks on a brand new boat with a 496 HO. It only leaked at the upper end of the rpms 496 HO --- the water pressure over came the drain valves - the water leak would start at 4800 thru 5000 rpms ONLY --- were water pressure was the highest psi

food for thought for you guys whom can not find your water leaks in the water actuator drain systems.

To find your water drain - use the blue air pump - pump away and you will see on each side of the engine where the water is draining from the engine. .

Have to ask now, are you the one I met at the Buffalo Poker Run about 3 or 4 years ago with a single whippled 486 in a 26 Sonic ??? If so I told you back then where your water leak was coming from. Or maybe you bought the boat off that guy who owned it 3 or 4 years ago ? JUST ASKING

no bup never was at the buffalo poker run. I have had this 31 sonic since 2006 it's a 2002. and do my boating in the Hudson river 60 miles north of new York city.

Thanks got the info it was not you then. SO now you can go fix your leak haha

I've had to replace those air actuators in the past. The springs wear out over time.
The spring holds them CLOSED. Applying air to the system pushes the actuators against the spring to allow water to drain out.
There is one on the port front of each motor. And one on the aft starboard of each motor. All are down next to the oil pan. I hope that if you have an issue, it's with one of the front ones!
Of note, they are not required. You can remove the actuator and replace it with a small section of pipe if needed.