# Yanmar 3GM30 salt water in intake manifold



## Peregrina (Mar 24, 2008)

My 1983 3GM30 which I start weekly got difficult to start two weeks ago...I finally got it to start as if it were cold (I am in Puerto Rico) by opening the throttle all the way. Last week, when I tried to start it, it wouldn't even turn over, and, thinking it might be a bad starter connection, I went to visually inspect it...and saw seawater dripping from the air filter above the starter. I apparently had what we used to call a "liquid lock" on radial engines...using the levers to decompress the cylinders, I was able to turn the engine over and that way get rid of the water, then returning to compression, got it to start. I closed the seacock before I shut it off, to avoid leaving it full of water, and I called a mechanic who said he thought it was the syphon arrangement that connects the exhaust manifold with the mixing elbow (which was replaced about 6 months ago) He replaced that, and we started the engine (again full throttle). He said that was probably because it was wet.... That was on Thursday. Yesterday, Sunday, I tried to start it and it wouldn't turn over. The intake manifold was so full of water that it had overflowed and there was water in the air filter. I got it started the same way as before (full throttle after purging it), but I know that if I haven't damaged the engine yet I soon will. Can anyone suggest what the hell is going on?

Thanks,
Chuck (Peregrina, a Freedom 32)


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## toewsrus (Mar 15, 2007)

Sea Water in the engine. Water Lock, Liquid Lock, whatever you call it, it's not good and will ruin your engine. I have the 3GM30F as well. does yours have an F at the end of the model number, meaning it's freshwater (antifreeze) cooled, or is it strait seawater cooled and no F?

I went to a 3 day Yanmar course last week, I think it was one of the first things he told us: don't crank your engine longer than 20 seconds total (5 seconds now, 5 later, 5 later on and then 5 more) (or 20 seconds all at once). If you do, the muffler must be drained. The seawater will accumulate and not get pushed out by the cranking engine. It's a running engine's exhuast pressure that pushes the seawater overboard.

Liquid Lock will bend or break your connecting rods. I'm not sure of the extent of your damage. But if it's running, I would start with an oil change, then another, and probably a good once over by your mechanic.

If it's not a freshwater cooled (No F after the 3GM30) and the water is coming in by itself and not because of over cranking, I would suspect a blown gasket or crack in the head or block. Either way it involves major engine work.

Please let us know how it goes!


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## MedSailor (Mar 30, 2008)

What makes you think you have a liquid lock? If you have sea water dripping on the starter and it got PROGRESSIVELY harder to start you might just have corrosion on the starter/solenoid connections. This is very easy to diagnose. First, look at the connections. Do they look corroded?

Take a multimeter and test your voltage at the battery posts. Hopefully it is 12.8V. Then test it on the two posts of the solenoid. Is it 12.2? That would make the engine start sluggishly. 

To fix take off and clean the connections. Oh and fix the saltwater leak. I would recommend removing the battery cables at the battery first though as I once touched both poles of the solenoid with a metal wrench. It instantly arc-welded the wrench to the posts and began starting the engine. Scared the %%$$!!! out of me!  

You also may have corrosion in the starter. I once submerged my yanmar starter in sea water (don't ask) and it was pretty straight forward to "carefully" pull it apart, clean it and put it back together using the exploded diagram from the yanmar manual.

Hope this helps.

MedSailor


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## jrd22 (Nov 14, 2000)

We have the same engine and I once got seawater in the cylinders while trying to bleed the injection system before I knew it could happen(actually flooded the engine 2-3 times before figuring it out-kind of a high stress situation). The engine was OK (this happened several years ago) but got progressively harder to start over the next year or so. We eventually had the injectors reconditioned and it helped the hard starting quite a bit. The salt water is really hard on the injector nozzles, they don't atomize the fuel properly making it harder to ignite. I don't understand how you are continuing to get water in the engine if you have your seacock closed after you shut the engine down. Is there any way water can be siphoning back through the exhaust system?

Good luck,
John


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## Peregrina (Mar 24, 2008)

John:
Thanks for replying...I suspect the ever-more-difficult starting may be what you describe with respect to the injectors...but before I can fix those I have to figure out where the water is coming from. I have actually been closing the seacock before shutting down the engine to try and avoid having water retained in the manifold...but where's it coming from? The hose that connects between the exhaust manifold and the mixing elbow is routed in a high curve to theoretically preclude syphoning...so far I'm not getting water in the engine oil, but that'll be the next thing if my rings seize up.... Is a puzzlement.
Chuck


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## Peregrina (Mar 24, 2008)

Mike:
Which came first, the slow starting or the chicken? Or the egg? After reading what you point out about the 20-second cranking, I think you've answered where the salt water's coming from. But this engine was rebuilt about a year ago, and we used it last summer upwind to St. Thomas on the way to Virgin Gorda, and later at Thanksgiving on the way to St. John...but now instead of asking where the water's coming from I should be asking why's it starting so hard...what fouled the injectors?


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## Rockter (Sep 11, 2006)

Well, you are either syphoning, or you have breached the exhaust manifold barrier between coolant and combustion exhaust.
I trust you have a siphon break? If so, make sure it's working. Check the wee non-return valve on it.
If that does not work, then take the exhaust manifold off there and you should see the leak path across the gasket(s). The gasket will not leak inward when running, but it will when shut down. If the drip was fairly fast out of the air filters, I would not suspect the exhaust gasket.


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## bubb2 (Nov 9, 2002)

Check your vented loop


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## Peregrina (Mar 24, 2008)

Rocter:
Thanks! I was away from the boat (I live in the mountains) and had a mechanic check the siphon...he took out a pvc that was mounted between the exhaust manifold and the mixing elbow...no valve whatsoever in that...and installed another "antisyphon" loop...which looks pretty much the same to me; a short hose going up, a fitting, and another coming down to the elbow, with a small tube clipped to the firewall with one end open. I confess I don't understand how that works, and my Yanmar documentation doesn't show anything like that. It was actually more than a drip; there was water standing in the manifold and what was dripping was leaking out of the filter cover....
Chuck


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## jrd22 (Nov 14, 2000)

If the water you saw dripping from the air cleaner and in the intake manifold was saltwater then I don't think you have a leak into the coolant jacket. When trying to start it leave the seacock closed until it fires off then open immediately, running the engine is the best thing you can do for it right now to get oil on the cyl. liners and rings. Have you been able to run the engine since installing the siphon break, has it stopped the water from filling the engine?

John


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## Rockter (Sep 11, 2006)

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.


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## Peregrina (Mar 24, 2008)

*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


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## Rockter (Sep 11, 2006)

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.


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## sailingdog (Mar 19, 2006)

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.


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## xcbxer (Mar 19, 2008)

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


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## Peregrina (Mar 24, 2008)

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)


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## Peregrina (Mar 24, 2008)

*Yanmar 3GM30 (salt water) cylinder head*

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


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## Rockter (Sep 11, 2006)

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


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## sailingdog (Mar 19, 2006)

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


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