Yanmar 3GM30 salt water in intake manifold

[Rockter]

Yes, but the moment you shut it off, the water will run in there again.

The idea of a siphon break is a wee valve at the top of a raised loop. The valve stays shut if the coolant water pressure inside the pipe is higher than outside (engine running), but opens promptly if the opposite is true (engine shut and coolant racing away (both directions) from the top of the loop. When it opens, the circuit can only draw air, and not water. If it can draw water, there is a risk that the engine can get filled up when shut off.

You have to service them once in a while, as it is claimed they get fouled with salt, and stick shut. If they stick open, it is obvious.... they just squirt water up and everywhere.

[Peregrina]

John:
Yes, I started it again (the same difficulty, had to open the throttle all the way and crank it longer than I like to); once it's started it runs fine but I think it's still syphoning, I close the seacock prior to shutting it off. Any water I get has to be seawater; this is a plain Jane 3GM30, no intercooler, seawater cooled.
Chuck

[Rockter]

Pere...
Pull this trick:
Get two good men and true.
Loosen the fittings on the pipe just DOWNSTREAM of the siphon break, but do not disconnect them yet.
Start the motor, and run it up to operating temperature, and leave the motor running.
Send the other man up to the cockpit and have him standby to stop the motor.
Now, quickly, pull the hose off the DOWNSTREAM side of the syphon break. Water will fly everywhere and when it does, shut down the motor immediately.
Now watch those air filters again. Does the water drip out this time? If it does NOT, then the problem is very likely to be the syphon break.
If it still does, then suspect that the exhaust manifold is breached.
I speak from a little experience, in 1997, in the semi dark of the motor bay, I fitted one of the three exhaust gaskets on the Volvo MD17c (raw water cooled) the wrong way round such that the seal between exhaust and entry coolant was lost. The symptoms were exactly as you describe. It would run fine, but dripped out of the filters when shut down.

A corrosion breach would give the same symptoms. I doubt if you have a corrosion breach. They really corrode very slowly indeed. If you have a breach, you can re-skim the exhaust manifold for a few bucks, assuming the material loss is in the manifold.

Whatever you do, do not let that motor lock up on you.

Rockter.

[sailingdog]

Most water-lift mufflers will fill up with water and then flood the engine through an exhaust valve if you crank the engine for an extended period of time. If you have to crank the engine for an extended period of time, you really should close the raw water intake seacock for the water lift muffler. JUST DON'T FORGET TO OPEN IT once the engine is running.

[xcbxer]

First post here - and just my luck, Sailingdog is watching....

I don't know the Freedom 32 layout but in my view it's critical that the incoming raw water has no possibilty to siphon into the exhaust valves after shutdown. Various websites recommend water to engine connections at least 12" above waterline or an anti siphon valve that needs to be regularly checked for sticking. As an alternative I suppose you could immediately run down and close the thruhull every time the engine is shut down.

Without the anti siphon valve a riser by itself is not enough. The water could still siphon uphill using the very convenient water filled small diameter submersed intake line, then back up against against the exhaust riser, and flood the engine.

On the exhaust side the thruhull is thankfully above the waterline, the diameter is larger, and the riser is usually substantial, so unless the boat is overloaded, heeled or attacked by wierd wave action, siphoning is not as likely to happen.

Hard to believe this day and age that 20 seconds of cranking can sink a properly installed $20K engine. Also hard to believe idling will glaze it up; don't truckers do this all the time? oops, sorry - that's probably a new thread.

Mike

[Peregrina]

I've been connected to Sailnet for less than a week and already I'm grateful to a whole bunch of people...I think you've given me a handle on what's happening, my major problem now is I have classes until Thursday, so I won't have a chance to check it out until Friday. As soon as I verify anything, I'll let you all know. Thanks! Chuck (Peregrina)

[Peregrina]

Checked out all the exhaust manifold, antisiphon etc. suggestions...finally found no compression on #2 cylinder. Removed head, and found a repair made in St. Thomas several years ago had finally failed again (blown gasket, channel burnt in head, welded, rectified, reinstalled w/ new gasket). Anyone know where I might get a used head? How much does a new head cost? I found this out yesterday after everything on the island had closed.
Chuck

[Rockter]

Well, now you know. The coolant had breached the jacket.

[sailingdog]

Ouch... that pretty much sucks...but if you get a new head, it'll hopefully, be far more reliable.