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  Topic Review (Newest First)
08-01-2012 10:06 PM
Re: destroyed impeller

Thanks, I did the back flush thing and even better than checking the input hoses, I replaced them with new. I really did not find any pieces, so they must have been ground up (there was a lot of 'black dust' in the intake water pump). She seems to be good as the Yanmar starts right up and runs just fine. The oil and the coolant look good too. The scale buildup did not look too bad so I put that off until another day. We have a Moonlight cruise coming up this week and I wanted to get everything back together and tested as soon as possible. So far so good.

08-01-2012 09:55 AM
Re: destroyed impeller

Originally Posted by CapnRon47 View Post

When I got home I took apart the 'old' pump and found 4 of the six impeller blades still in the pump but un-attached. I am assuming the other two are working their way up into the heat exchanger and will eventually plug the mixing elbow. So I plan to back flush the heat exchanger to see if I can clean it out. Any thoughts, comments or suggestions on this procedure. I had not planned to open the end face plate of the heat exchanger, just flush it using the output and input hose connections. But I could be convinced otherwise.


Unless you've already made this effort and my comments are redundant, simply back washing with a garden hose to the output side of the heat exchanger and a hose to a bucket on the input side should wash out the "bits 'n pieces". If they do not appear, check the hose between your raw water pump and the heat exchanger as they may be lodged there.

Once you've recovered the debris, to clean out the tube bundle itself, you can use a cleaning agent like RydLyme or Barnacle Buster in a bucket with a small inexpensive submersible bilge pump ($29.00 at WM). A hose from the pump is connected to the discharge side of the heat exchanger and the hose from the input side is led back to the bucket. You can power the pump with some jumpers led back to your house bank. By recirculating a solution of RydLyme in this manner, you will remove most of the scale that may/will have built up in your tube bundle. If you are worried about debris being recirculated, a couple of wraps of cheese-cloth around the base of the submersible pump makes a pretty efficient filter without obstructing flow. You can test the efficacy of the solution by dipping a shell in the bucket. As long as it "fizzes" the stuffs still good. Four to six hours should be more than long enough with RydLyme although there is a table of recirculation times on the company's web-site.

In future, hang your ignition key on the handle of your raw water through hull.

07-30-2012 11:03 PM
Re: destroyed impeller

Sorry, I cannot help as I am not familiar with the Atomic 4, you might start another thread and ask the question as people with Atomics may not be monitoring this thread as they know it is about a Yanmar.

07-30-2012 02:48 PM
Re: destroyed impeller

Originally Posted by Faster View Post
Oh.. and you've heard of the trick of storing the engine key on the through hull valve handle????
^^^ This.

Tho until grabbing that key and opening the valve becomes habit, if you've a spare key, say, in a drawer in the galley, best put it away somewhere else.

It was the end of our first season keeping the key stored on the thru-hull valve handle and I was taking her over to the pump-out just prior to haulout. Tied up at the pump-out dock, grabbed the "key" for the deck pump-out fitting and... it didn't fit?!?! What the blue blazes? Check the drawer. Nope, that had to be it, because there was nothing else in the.... waitaminute... there should be two "keys" in there: One for the water tank and one for the pump-out. Looked up at the engine key switch and there it was. Oh no... Sure enough: The normal key was still hooked around the handle of the closed through-hull valve.

Luckily it was fairly cool water and air that time of year and I hadn't gone far. The impeller was fine.

07-30-2012 01:13 PM
Re: destroyed impeller

This is a little off the topic. Hope you don't mind. I have an atomic four engine and the water pump isn't being turned by the engine so it is overheating. I looked where the water pump shaft enters the engine and there is nothing there to interact with the water pump. Did something disintegrate? Any thoughts?
07-03-2012 09:52 PM
Re: destroyed impeller

Nice job, Capn, It's always good to hear the results of these issues. Glad it all worked out.

I've had to do exactly what you just went through. Like you, I got to know my engine; it is satisfying. This is my 1st diesel...after having an atomic 4 for a long time.
07-03-2012 09:41 PM
Re: destroyed impeller

Just to bring this to closure. I disassembled the heat exchanger, I never did find the last 2 blades of the impeller, so I am assuming they ended up as grit and dust in the original raw water pump. I cleaned the heat exchanger (the best I could, I will try the vinegar at some point), and reassembled with new o-rings, seals and hoses (just because it was time). Opened up the end of the heat exchanger looks like this;

Initially I had a frozen bolt, I used Blaster 16-PB, left it overnight and that did the trick. The engine coolant outflow nozzle was pretty rusted, but still thick enough, so I cleaned it and used Permatex Ultra-Copper as a coating before I put the new hose on it.

After reassembly I ran the engine thru its passes and found no leaks and water flowing fine out the exhaust. This is my first boat so I am learning as I go, it is satisfying to get things back together and have them work the first time. A bit of time (and money) is all it took!

thanks for all the input.
06-22-2012 06:25 PM
Re: destroyed impeller

Thanks, sounds like a fairly straight forward project for this weekend, I will go with eventually removing the end plate (I may try the vinegar flush first), it is only 4 bolts (it would be a good time to put anti-seize on them as well, as I do everything I take apart and put back together.)

I still like the idea of a valve with a sensor built in, even if it just went to a light on the panel, you could tell by a quick look what was open and what was closed. Instead of the guessing game, did I close that one, well lets check.

Speed seal look like an interesting product, but the damn faceplate screws are on the engine side of the pump. I guess they have to be because the pulley is on the front side. Anyway if the impeller did not break down by running dry that would be a plus.

thanks all,
06-22-2012 01:50 PM
Re: destroyed impeller

If your Yanmar is like my 2GM20F, the exchanger doesn't have coils, but simple straight-through pipes arranged in a cylinder--looks like a Gatling gun barrel. You should be able to clear the front of them by removing the forward cap on the exchanger. Four bolts I think.
06-22-2012 10:37 AM
Re: destroyed impeller

CaptRon, been there done that! Like every one else has said, you'll want to find those blades. I also recommend hanging the key on the seacock. Key has lived there since I learned my lesson.

Also IIRC Yanmar recommends having the valves adjusted after overheating the engine. Took about an hour on my 3GM for the mechanic to do it & truth be told he said the clearance on the valves was okay but, better safe than sorry.

PS I commend you for having a spare pump. They are a b%^ch to replace while at sea.
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