Air actuated drain systems

[ct77]

Hi Guys,

I have a 2002 Mercury 350 MAG MPI Tow Sports engine in my V-drive wakeboard boat. It has the air actuated drain system

I pulled the boat out of the garage to run on the hose and get ready for the season. When I turned on the water, if ran right out the bottom of the brass sea pump. What seems to be happening is the water is pressurizing the sea pump, which opens the valve and allows water to pour out of the bottom.

I've taken the sea pump off the motor to inspect and replace the impeller since I'm there.

I put my hose fitting to the pump on the work bench and it seems I can replicate the problem, water is coming out of the air hose fitting, which runs to the schrader valve on top of the motor, building pressure and opening the valve.

Has anyone else out there experienced the same problem?

The parts manual does not have replacement seals/o-rings for that part of the pump, seems kind of strange??

Thanks for any help!

 

[Don S]

Re: Air actuated drain systems

Below is a breakdown of the pump, is the hole where the blue plastic plug (item 10) where the water is coming from?

 

[ct77]

Re: Air actuated drain systems

Hi Don, The blue plugs are good. Looking at the diagram, it is coming from the under side of the sea pump, from the bottom of that vertical portion of the pump body behind #11. I removed the snap ring from the top of #8 and there is a piston with 3 o-rings and one seal. I think that water is getting passed those seals on the piston and traveling up through #14 (the air lines). Water in air lines is building up the pressure and releasing the valve.

 

[ct77]

Re: Air actuated drain systems

Update: I've confirmed the problem with my local dealer. They say its not super common but it does happen and usually sandy water (which we have here in southern utah) is the root cause. I have a parts catalog for the motor and it shows two separate part numbers for the front and back half of the sea pump, like the diagram above. Unfortunately, Mercury has updated part numbers and you can only get the entire pump, $550 or so. I had the dealer run the part number for item #8 above and they actually had 6 left! The cost for the back half of sea pump is about $250. I will post another update once the part comes in and I finish the job.

I really like the air actuated drain system, my only concern is what to do if this problem happened on the water rather than in my driveway? Maybe this would be a good time to put a ball valve on the sea water pick up line?

 

[Bondo]

Re: Air actuated drain systems

I really like the air actuated drain system,

Ayuh,.... I don't...

When the lower block passages load up with that Sand, along with some rust flake, 'n other general cooling system Crud...
You'll use that system Thinking you've drained yer block for the winter...
Come spring,...
Yer buying a New Motor, because the Crud blocked the drains, 'n it froze, 'n Cracked....

I'll take a plain ole 1/4" brass pipe plug, 'n a 3" deckscrew layin' on the intake anyday over yer Air operated fancy drainin' system...
My 9/16" socket, 'n that deckscrew, Guarantee that the water is Gone, 'n the block is Dry for winter...

Glad to hear ya found exactly what yer Problem is though...

my only concern is what to do if this problem happened on the water rather than in my driveway?

Yer boat should have Bilge Pump Capacity to cover such a thing....