Vented loop for FWC?

[Johnman135]

I'm in the process of putting my new Moyer rebuilt with FWC into my Tartan 30.
The previous installation was raw water cooled and had a vented loop installed above the water line in-between the raw water output ( exhaust manifold ) and the exhaust water injection. Is this loop still required with FWC?

[hanleyclifford]

Still a Good Idea

That loop is to prevent a syphon of water into the engine. It is still necessary with FWC unless you religiously shut off the raw water intake whenever the engine is not running - and I mean ultra orthodox.

[BadaBing]

Tartan 30s "normally" use a Standpipe to mix the exhaust gasses and cooling discharge water togeather before the flex rubber hose that connects to the through hull exhaust port.
The Standpipe removes the need for an anti siphon valve or loop. It actually serves that purpose itself IF installed properly.

[hanleyclifford]

Tartan 30s "normally" use a Standpipe to mix the exhaust gasses and cooling discharge water togeather before the flex rubber hose that connects to the through hull exhaust port.
The Standpipe removes the need for an anti siphon valve or loop. It actually serves that purpose itself IF installed properly.

if indeed he still has the standpipe system.

[BunnyPlanet169]

That loop is to prevent a syphon of water into the engine. It is still necessary with FWC unless you religiously shut off the raw water intake whenever the engine is not running - and I mean ultra orthodox.

+1 Any raw water hose that does not terminate above the waterline needs a anti-siphon vent loop well above the waterline. Don't forget angle of heel....

[Skywalker]

Hi guys.

Went to the boat this morning to confirm that my carb rebuild successfully stoped fuel from filling the carb when the engine was off. Had to adjust the floats a little, but all seems fine now.

When I went out for a cruise around the harbor to check everything, I was startled by my high water alarm going off! Never went off before. I turned tail back to my mooring, all the while pumping away with my hand pump. Made it back, tore things apart looking for a leak. Nothing. Intake, cockpit drains, transducer, sink...nothing.

Fired up the A4. Nothing. Wait. I hear something.

A couple of seasons ago I replaced the anti siphon loop. It was a bronze fitting with a nylon valve. The valve would occasionally spit so i added a piece of hose and ran it away from spitting on my A4. Well, with the engine running, this little hose was pissing a steady stream. Took it apart. The nylon valve was no longer working, so off to a couple of stores before I could find an total replacement.

No one had a bronze fitting. I went with a Marlon fitting thinking the water temperature from the heat exchanging is warm at best.

I ran the engine for a hour. The temperature of the hoses remained cool. There does not appear to be an issue.

Any thoughts on whether this is acceptable?

Thanks.

Chris

[ndutton]

Your Marelon loop should work fine. When working properly the antisiphon valve does spit and you're right, it is a nuisance. When the valve fails, as you experienced it can be dangerous. Thank goodness for your high water alarm.

An alternate antisiphon method is to do away with the valve and run a hose from the top of the loop to an overboard drain. Mine runs to the galley sink drain, others to a cockpit drain. With this system there is no valve to fail, no irritating spitting and no filling the bilge.

One more comment, trusting the carburetor's float valve to hold back fuel when you're not at the boat is risky. One speck of debris on the valve can allow fuel to pass, overflowing the carb and into the bilge. Depending on how long the boat is unattended, there could be a significant and dangerous amount of fuel spilled. Please consider a manual fuel shut off valve immediately ahead of the carburetor for ultimate safety. Working for the sailboat manufacturers we were always warned that one cup of vaporized gasoline had the explosive force of three sticks of dynamite.

[Skywalker]

Thanks for making me feel safe about the Marlon, but now I'll be up all night worrying about an explosion!

All kidding aside, I was looking for a way to add a shut off valve. The interior of the T27 makes this a little tricky. I have a shut off south of the tank, north of the fuel/water separator that I use for long periods away, but it is a PITA to get to.

My best solution is to add a couple of feet of fuel line and put a cut off in the port locker or on the aft bulkhead.

But as always, thanks for the help.

Chris

[ndutton]

Again, you are correct. Easy access to the valve is an important element.

[edwardc]

My 1977 Pearson has an OEM electric fuel cutoff valve mounted right at the tank. I believe the brand is fuel-trol, or something like that.
Wired to the ignition.

[BunnyPlanet169]

This is worth a close read. Even if you can't meet the requirements exactly, you can see the intent. If you were a professional doing a refit, you'd want to meet or exceed the requirements.

http://www.moyermarine.com/forums/showthread.php?t=9280

[joe_db]

When I am done for the day I shut my fuel pump off and let the engine run the gas out of the carb. The engine cannot siphon gas and keep running, so it also does not have gas to leak

[Skywalker]

I spent the last couple of days trying to find a shut off valve that I can mount on the rear bulkhead. No luck so far.

I know I will not tear the thing apart to get to a shut off valve. There is an open spot, right above the carb, that would be ideal, but all I have found so far are in line valves.

Any suggestions would be appreciated.

[BunnyPlanet169]

In-line, meaning hose barb?

McMaster has some threaded valves both F-F and M-F. Found this in a previous thread - some of them are UL listed.

https://www.mcmaster.com/#catalog/123/468/=17cmg2y

[Skywalker]

Thanks for the link.

I am hoping to find a fitting I can mount through my rear bulkhead so the hoses stay in the engine compartment and the valve can be operated from the interior of the saloon.

So far, I am finding surface mounts, not through mounts.