No water from exhaust

[capt jgw]

Originally Posted by Stu Jackson

Also check the rw pump faceplate. if it is not flat flat flat it could stop pumping.

If the back side of the pump body is scored that can stop it too. You have to replace the whole pump to fix that.

[Creewind]

First off Thank You very much to all who chimed in. I appreciate all suggestions.



UPDATE! I now have ample water flow. However I have no idea what it was. Here is what I did.
With the brand new impeller installed I too the hose off the input to the cooling head. Started the motor. NO WATER.. ran the motor about 30 sec. Turned it off went to the water pump took the hose off it. Ran the motor. We DO HAVE WATER coming out. OK.. easy check the hose blocked. But it wasn't .. No blockage .. it was clear. Put it back on and just for laughs started the motor.. WATER FLOWING out perfect. We found no blockage at all. Nothing came out of the hose. We intentionally watched for something. Let the motor run about 45 minutes at 2000 RPM.. We cleared nor fixed anything. I'm happy it's running now BUT.. now lacking the confidence to use it on a longer cruise. We did inspect the elbow coming out of the back of the heating header. Looks clear. No build up of anything.

SOOO if there are any ideas of what could cause the flow to stop than start.

[MikeHoncho]

I had a impeller break apart, changed it and had over heating issues. Everything looked ok when pulling the hoses. I let the hose running to the engin from the pump fall into the bilges while disconnected from the engine side and chunks of impeller flowed out with the water. I also found junks stuck in the discharge side of the pump. If your impeller failed like this I’d check the raw water circuit to include the heat exchanger if it is fresh water cooled.

[Cheechako]

Originally Posted by Creewind

First off Thank You very much to all who chimed in. I appreciate all suggestions.



UPDATE! I now have ample water flow. However I have no idea what it was. Here is what I did.
With the brand new impeller installed I too the hose off the input to the cooling head. Started the motor. NO WATER.. ran the motor about 30 sec. Turned it off went to the water pump took the hose off it. Ran the motor. We DO HAVE WATER coming out. OK.. easy check the hose blocked. But it wasn't .. No blockage .. it was clear. Put it back on and just for laughs started the motor.. WATER FLOWING out perfect. We found no blockage at all. Nothing came out of the hose. We intentionally watched for something. Let the motor run about 45 minutes at 2000 RPM.. We cleared nor fixed anything. I'm happy it's running now BUT.. now lacking the confidence to use it on a longer cruise. We did inspect the elbow coming out of the back of the heating header. Looks clear. No build up of anything.

SOOO if there are any ideas of what could cause the flow to stop than start.

How high in the boat does the engine sit? It sounds like you had an air lock of some sort. Is the b oat new to you? What is the boat?

I had a problem once with a larger engine. The thermostat was closed because the engine was cold. There was air in the system. The thermostat was surrounded by nothing but air. So the heat wouldn't get to it to open it! I had to open the housing and pour in hot water, then seal it up and start the engine. It was fine after that. (FYI, I had had a hose off the engine which caused this)

Of course this was the fresh water side. but just an example of what an air bubble can do. Is it possible your impellor is sitting in air and not pulling water? maybe not. Just a wild thought.

[Mickeyrouse]

My first guess is that by removing the hose(s) you dislodged the blockage. Stranger things have happened.
I would share your anxiety about long distance reliability. Run the engine in gear secured to the dock for extended periods, half an hour or so. Watch the temp and water flow. If the condition doesn’t re-appear after a few sessions of this, you’re probably okay. That doesn’t mean something else won’t crop up. It’s a man-made engine, after all.

[Creewind]

First .. It's a 28 ft. Pearson sailboat. the motor replaced the existing Atomic 4 many years ago. Before I bought the boat. I've had it now about 6 years and the motor is flawless and I do do regular maintenance.

Also today when I took the hoses off and put them back on I did run the boat about 45 min. at about 2000 RMP including in gear for a short while. No problem.

[Creewind]

Originally Posted by capt jgw

If the inside is scored, and there's no writing or anything stamped on the outside, you can usually just flip it over. Brand new surface should last as long as the original one.

I did check this and I found I was missing the gasket. I replaced it. However the motor has been running like this a long time. You may have something here though Just took time for the air to leak in. I never leaked water out.

[capt jgw]

Originally Posted by Creewind

I did check this and I found I was missing the gasket. I replaced it. However the motor has been running like this a long time. You may have something here though Just took time for the air to leak in. I never leaked water out.

Soon after buying one of my prior boats I found the cover plate sealed on with silicone, no gasket at all. And it was not leaking. I was pretty surprised. And good to know you can do that in a pinch. Those paper thin gaskets are a pita, when they get wet they fall apart and darn near impossible to reuse. If you cut a new one from thicker material the pump won't move water. The newer pumps with a rubber O ring are a definite improvement.

[s/v Jedi]

I guess a plastic bag was sucked against / in the thru-hull and it went away when you took the hose off.

I would check impeller and injection elbow still.

[Mickeyrouse]

As to the self-curing mystery: ofttimes when the impeller vanes break off, they can get lodged somewhere in the system. They are just big enough to block the discharge. Over time, with a newer, more efficient pump-impeller, it’s very possible that the pieces of the impeller that were lodged somewhere in the system finally got flushed out.

[sailorladd]

You might check the thermostat, sometimes they get stuck closed...my vetus MD# had that issue and it also would overheat... removed the thermostat and end of problems...

[MHTinkler]

I have a 27 HP Westerbeke diesel, but like all marine engines regardless of make, have a similar raw water pump. My experience - whenever I lose water from the system I must always prime the system before the raw water pump will move any water. A pump of this design ( vane) really pushes water well but sucks at sucking. Moving water out of the system creates low pressure behind it and atmospheric pressure pushes water in to fill the void. My solution has been to fill the system using my water maker primary pump until water flows freely from the exhaust port at back of boat. (Keeps pump vanes from burning up).
Also if ever the engine is not run for long
periods , it will dry out and must be reprimed.

[Shaneesprit]

Originally Posted by Creewind

I have a Yanmar 2gm20F. I checked and verified ample water was coming through the through hull. Strainer is clear, a new impeller is installed. I am going to check how far the water goes from the pump .. ie to the header tank and out the other side. What else should I consider?

OK.. NOW.. what else should I do??

Did you fit the correct Impeller ? Didn’t put a 6 blade impeller if it should of been a 10 blade one?
I don’t know which you should have but the wrong one won’t work.

[Sea Crawler]

Creewind,

I also have a Yanmar 2GM20F diesel engine and I can confirm that it is indeed a fresh-water cooled system that doesn't have any anodes in its heat exchanger.

The thermostat controls the coolant side of the heat exchanger. You can safely eliminate looking for a zinc or at the thermostat as being possible sources of your "intermittent" (No water from exhaust) problem.

Any broken sea water pump vanes or bits (vanes, grass, sea life, etc) could lodge themselves behind the endcap at the front of the heat exchanger or at the rear end cap, and under the right conditions, could clog the opening at the exhaust mixing elbow.

If you haven't found the cause of your blockage, I suggest you look at those areas as some others have suggested.


Tip: If you don't want to dismantle the end caps, a clean shopvac can be handy to extract the broken vanes and bits lodged at the front of the heat exchanger. To do so, you would need the pull the hoses off the front and rear end caps.

[VIKINGBEAR]

I have a Universal M25 and recently had the same problem. One day, no water at the exhaust. Started troubleshooting along the same lines as previously mentioned by others here.
Finally concluded that the problem was in the 3” heat exchanger – installed new 2 years ago - and took it off to inspect/clean.
Found that there was a buildup of a hard “shell” totally blocking any raw water from exiting the HX. This shell was about 1 ½”x 1”and must be some kind of very tiny planktons or similar that found their way in through the tiny tubes and decided to take up residence in this spot. Over time others came in and settled there as well. By the time I found it, the mass was rock hard, had to lightly hammer it out. The rest of the HX was relatively clean, no obstruction in other areas. Hope my pictures will download properly…...
After putting the HX back I now have more water flowing at the exhaust than before.
I believe this can happen if the engine is not run often, giving the critters time to attach themselves instead of being washed overboard. By the way, I also installed new impeller and inspected and replaced all hoses in the raw water system including the 5/8” vented loop between the HX and the exhaust elbow. Also dismantled and inspected the riser/elbow (Yanmar type) which was found to be ok.