No water exiting my engine.

Hi all, hoping for some help with this. There isn't any water exiting my boat. I have a Yanmar 3GM30F engine. The seacock for raw water will open and close. The raw water strainer is clean. The impeller looks good (see pictures) yet still no water coming out the back of the boat. Does anyone have any ideas? I should also mention the the engine only has about 1,100 hours on it.

You mentioned that, "The seacock for raw water will open and close." Does that mean that water is coming into the boat? I had an air condition seacock completely clogged by a sea nettle (stinging Chesapeake jelly fish) that caused the AC unit to shut down. I checked the pump, strainer and finally the sea cock by taking the hose off and opening the valve and still no water came in but there were strands of sea nettle up into the hose. I thought a haul out was in my future because even pushing it with a coat hanger didn't clear the obstruction. So I re-connected the hose, disconnected at the strainer and with the mightiest breath I could muster blew into the hose sever times (with the valve open of course) and finally the "head" of the sea nettle popped off and water flowed again. I went topside to see the beheaded creature floating away from the boat.

Of course, I guess that you already have seen water entering your strainer after you take the lid off. But checking if water is coming is the first and easiest step in trouble shooting this problem.

I also have the 3GM30F. Couple things to check, first and foremast being the exhaust elbow. Has it ever been replaced or cleaned out? It's a known choke point for carbon buildup, which can prevent the flow of water. Also, if you can, get a 5 gallon bucket, fill it with water, disconnect the raw water hose (close the seacock first!), put it in the bucket and fire up the engine. If water comes out, then you might have an issue with the intake thru-hull. And of course, there is also the possibility that the exhaust hose itself is plugged with something. Critters have been known to nest in those things during the offseason. Good luck.

Christian Williams said:

No Water From Engine Exhaust (Master Thread)

Thread formerly titled "Seawater not pumping through engine" I've got an M25 which starts and runs great but seawater suddenly stopped flowing through the engine. Here is what I tried so far: - disconnected input hose (that goes to thru-hull) from water pump on front of engine; and blew water...

ericsonyachts.org

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Thanks for the information!

bsangs said:

I also have the 3GM30F. Couple things to check, first and foremast being the exhaust elbow. Has it ever been replaced or cleaned out? It's a known choke point for carbon buildup, which can prevent the flow of water. Also, if you can, get a 5 gallon bucket, fill it with water, disconnect the raw water hose (close the seacock first!), put it in the bucket and fire up the engine. If water comes out, then you might have an issue with the intake thru-hull. And of course, there is also the possibility that the exhaust hose itself is plugged with something. Critters have been known to nest in those things during the offseason. Good luck.

Click to expand...

There is water coming in from the seacock. I opened the valve with the sea strainer off for a second. I'll check the exhaust elbow. The engine only has 1,100 hours on it, so I was hoping that there wouldn't be to much buildup yet. Stay tuned!

Bolo said:

You mentioned that, "The seacock for raw water will open and close." Does that mean that water is coming into the boat? I had an air condition seacock completely clogged by a sea nettle (stinging Chesapeake jelly fish) that caused the AC unit to shut down. I checked the pump, strainer and finally the sea cock by taking the hose off and opening the valve and still no water came in but there were strands of sea nettle up into the hose. I thought a haul out was in my future because even pushing it with a coat hanger didn't clear the obstruction. So I re-connected the hose, disconnected at the strainer and with the mightiest breath I could muster blew into the hose sever times (with the valve open of course) and finally the "head" of the sea nettle popped off and water flowed again. I went topside to see the beheaded creature floating away from the boat.

Of course, I guess that you already have seen water entering your strainer after you take the lid off. But checking if water is coming is the first and easiest step in trouble shooting this problem.

Click to expand...

There is water coming into the boat. Thanks for your comment!

Chuck Ray said:

There is water coming in from the seacock. I opened the valve with the sea strainer off for a second. I'll check the exhaust elbow. The engine only has 1,100 hours on it, so I was hoping that there wouldn't be to much buildup yet. Stay tuned!

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I don’t think engine hours count as much as how it’s run, when it comes to carbon. These engines require an occasional “blowout,” for lack of a better word, - run at near max for a bit - and if they’re consistently run at low RPMs, whether at idle or while motoring, the carbon deposits will be worse.

Recalling these parts in our boat, it is good to map out the whole path and check each part.
ThruHull fitting --> Hose to Strainer --> Hose to Raw Water Pump --> Raw water pump (impeller still attached to shaft, and water emerges from output side?) --> Hose to heat exchanger --> hose from H.E to exhaust elbow --> large exhaust hose to transom.
Apologies if I left out a part of the path!

The reason for this detailed list is that decades ago a mechanic explained how to troubleshoot my engine when it died and refused to start - i.e. find out where the dreaded "vacuum leak" was located. I used my dinghy air pump and duct taped a connection to blow thru sections of the whole fuel path starting from tank back to lift pump, and thru the two filters.
Found the problem, for sure, at the innocent-looking OEM factory Racor filter with an invisible air/vacuum leak somewhere in its housing. bypassed it and relied on the spin-on filter, and the engine could be quickly bled and started right up. No further problem, and I changed out the Racor in the fall.
He pointed out that often you just have to be very methodical in chasing leaks or blockages. Otherwise you find yourself jumping from one suspected place to another and getting (more n more) frustrated.

I'd look closely at the impeller to make sure the rubber part wasn't separated from its shaft and thus not spinning. It looks a little iffy to me.

Is the water coming out somewhere else? On our boat there is a vented loop thruhull that is above the exhaust exit that will always dribble a bit of water but if there is a flow restriction in the exhaust elbow it will stream out, for a full clog it is pretty impressive how far it will shoot out.

The fitting where water is injected into the exhaust elbow is a known location that can plug up. Our boat has a 90-degree fitting there. Often it is the "bio goo" from millions of little tiny cooked sea creatures that have slowly deposited themselves on the walls of that fitting and they will eventually block it up completely. Not super hard to clean, and you should remove it and clean it on some sort of schedule, but two things to keep in mind. 1. That goo smells really bad so try to do it on the boat or outside vs at home. 2. Wear gloves because if any of that goo juice gets on your skin, the smell will stick around for a few days and you will likely need to sleep in the basement until it fades away. Honestly, it might be worse than head hoses.

I second the infamous impeller separation issue. This is a very common problem, pull the cover and see if you can rotate the rubber manually. If it moves it's fubar.