ball valve on waterlock muffler. Good idea?

[Reefmagnet]

Hi All. as part of the process of the replacement of my engine, I'm rebuilding the waterlock muffler, which is made of stainless steel. It had a little bit of crevice corrosion in it and I also decided to change the exhaust diameter from 38 to 50mm to meet the specs of the engine.

The current exhaust has a ball valve fitted at the thruhull, which I've always found a little concerning because someone retrofitted it at some stage for a reason (the exhaust exist midships at the waterline rather than the transom). I suspect an earlier engine was destroyed by water ingress via the exhaust, especially when considering the top of the waterlock is only a handful of inches or so below the exhaust mixer.

Anyway, I digress. The idea came to me that I could fit a 1/2" ball valve to the waterlock as a means to allow the waterlock to drain excess water. Easy enough to do manually, but I'd really like to maybe have something operated with a morse cable so it could be turned on and off remotely.

Is the idea of a ball valve drain on the waterlock a good idea when used for the purpose of draining excess water whilst not motoring? Has anyone ever rigged up a remote morse control for a small ball valve with any success?


Thanks!

[Lepke]

I have drain valves on my mufflers that close when exhaust pressure builds. When the engines are shut down, the valve opens and the muffler drains. So the engines always get to start on an empty muffler with less back pressure and if necessary I can crank for awhile without worrying about water backing up into the engine.
Another way to do it is with a 12v solenoid valve wired to the ignition circuit.

[Q Xopa]

Originally Posted by Lepke

I have drain valves on my mufflers that close when exhaust pressure builds. When the engines are shut down, the valve opens and the muffler drains. So the engines always get to start on an empty muffler with less back pressure and if necessary I can crank for awhile without worrying about water backing up into the engine.
Another way to do it is with a 12v solenoid valve wired to the ignition circuit.

Sounds good, any more clues on what they are, where they can be got etc.

Thanks.

[Lepke]

Air compressor tanks have a valve at the bottom of the tank to drain the water that builds up in compressing moist air. Most places that sell air compressors or air tools usually has valves. Also auto parts stores. They can vary from manual, ac/dc controlled, diaphragm controlled, etc. Mine have a weak spring that holds open the valve until exhaust pressure overcomes the spring and closes the valve. When the engine stops the spring opens the valve and the mufflers drain.
12v dc air valves can be found at the same places or Amazon & ebay. From $10 -50. You use a normally open valve and usually operate it with a relay that energizes the valve when the key is on. Key on - valve opens and seals the drain, key off - valve closes and water drains. Usually in 1/4 or 1/8". 1/2" is more expensive.

12v valve shown is $17 on ebay:https://www.ebay.com/itm/Brass-Elect...kAAOSwpONZVlbK

[KadeyKrogen38]

Assure you have a working anti siphon valve fitted. If not you may be bringing in the ocean thru your drain valve when engine is off.

[briblack]

I'd think you want to get one that's minimally subject to corrosion. It's a tough environment.

[Brewgyver]

Yes, you want a valve with a Stainless Steel body for it to have any decent lifespan, but more importantly you must choose the right valve design for it to work at all.

Direct acting solenoid valves use a simple plunger to open a port for flow. This is the kind typically used on marine LPG installations. They don't have any minimum pressure differential to operate, but they also typically have low cV ratings, which is the limit of flow for a given valve size.

Pilot-actuated solenoid valves use a diaphragm to control flow, and have higher cV values, but typically require at least 5 psi differential to operate.

[Reefmagnet]

Thanks for the tips guys. I won't be using anything made of brass because I don't think it will last too long in that environment. I do have a brass electric solenoid valve on the head intake which works great, but it never comes into direct contact with sea water.



Yesterday, I re-fitted the revamped waterlock. I then figured out where I could fit a small ball valve and then I ordered the required bits off the interwebs. The plan is to install a 1/4" BSP ball valve. Because my main concern is sailing in poor weather allowing excess water to possible work it's way back to the waterlock, I don't see a need to use the valve every time the running state of the engine changes. I'm expecting to rig it with some sort of contraption that will most likely be cable operated or possibly electric. This contraption will simple act on the handle of the valve via a rod, so the valve itself doesn't need to be anything other than a standard manual type.

[kmacdonald]

Get a Vetus waterlock. Get rid of the valve. If it is closed and the engine is started that's the end of the engine. Google marine exhaust design so you get it right. Done wrong, the engine will be ruined. There's no second chance.

[Reefmagnet]

Originally Posted by kmacdonald

Get a Vetus waterlock. Get rid of the valve. If it is closed and the engine is started that's the end of the engine. Google marine exhaust design so you get it right. Done wrong, the engine will be ruined. There's no second chance.

I would if I could, but there is no waterlock on the market that would fit, hence why I rebuilt the original.


Totally agree with the ball valve on the exhaust. Totally stupid idea. Truth be known, I've never used it - which is a problem in itself as it tends to bind up - but the mechanic that tested the old motor for us pre-purchase many years ago started the engine with it closed and it caused the pressure to blow the hose off the back of the engine (which, ironically, was the same design of oversized exhaust elbow with attached tortured hose as in my other thread).