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destroyed impeller

4K views 22 replies 15 participants last post by  CapnRon47 
#1 ·
I took my kids (I still call them kids even though they are in their 30's) on as crew in a sailboat race. They had never sailed let alone raced, but it was a social race and low key (well at least for me). I am trying to explain a hundred things as we leave the dock and I forget to open the seacock to the engine. About 5 minutes later the overheat buzzer comes on and I immediately know what the issue is (funny how you remember things you did not do then). Opening the seacock did not help, so I shut down and began working thru where the problem was. Water was coming in, but not getting to the engine was what I found, so I replaced the intake pump. Fortunately, I long ago realized tryiing to change an impeller on a Yanmar was an upside down and back-wards affair, so I carry a spare entire pump, with impeller and bracket. I just need to swap out the new for the old. To make a short story long it is not quite that easy as I have an extra belt on my 30 GM Yanmar for my fridge compressor. I have to take apart the main pulley to remove that belt, but I was ready for that and had packed a bunch of tools on board. I dropped the hook, which allowed me to later use my newly installed wash down pump, but that is an even longer story. And in about 30 minutes we were back on our way with water nicely flowing out the exhaust and the engine running no worse for wear, at least I have not noticed any degradation of performance. I motored home, about 2 hours, after the race weekend and had no issues.

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.

thanks,
Ron
 
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#2 ·
someone needs to design a raw water sea valve that has a circuit interrupt to the starter switch. Glad you didn't have more damage then that Ron!
 
#3 ·
Not real familiar with that engine, but if there's an end plate you might get lucky by simply opening up the intake end and finding the remaining bits stuck there rather than having found their way into the tube bundle... If you can account for all the bits you're good to go.

Oh.. and you've heard of the trick of storing the engine key on the through hull valve handle???? ;)
 
#20 ·
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.

Jim
 
#6 ·
Denise,
I like the idea of a sensor on the input valve to start the engine. But, I usually prefer the simplest solution, the fact is I have NEVER done this before. I always open that valve and then check for the flow out of the exhaust before leaving my dock. But I was not at my dock and there were lots of distractions; the kids, other boats and backing out of a runway. Enough excuses, I messed up, but recovered. The boat next to me in the dock could not believe I changed the impeller while out in the channel, when I told him later. We missed the first race, but made it into the second. It actually worked out better as it gave me some time to work my new crew thru some tacks and jibes.

I can only assume my overtemp sensor went off before there was any real issue with the engine (what is the issue with on overheated diesel - running on?). I never saw any smoke or other indication of a problem with the engine. The engine always started right up as I was looking for the source of the problem.

Faster,
I store my engine key close to your suggestion, it is on the steps I have to remove to open the water intake valve. But not close enough this time.

thanks,
Ron
 
#7 ·
Dick,
That sounds like a good idea, but not sure how to go about cleaning the heat exchanger itself (the coils). I am usually an advocate of not fixing it if it is not broken, but you make a good point. I will have to dig out the engine manual to see how to remove the coils of the heat exchanger and whether it is worth that effort. After a little searching it seems I do not need to remove the coils to de-scale them. I can soak them in place with a chemical and then flush. Sounds like a good idea.

thanks,
Ron
 
#10 ·
Brian,
I was thinking more along the lines of the auto systems they had back in the 90's. When you would start the car it would say; "Your door is a jar!"

I could just image all the helpful comments we could a have on a sailboat designed by Detroit, well maybe I can't.


Ron
 
#12 ·
End plate. More work, perhaps, but finesse triumphs over brute force, engines can be clever about hiding stuff they've eeaten.

Denise, it would be simpe to take a magnetic reed switch (i.e. alarm window contact) and line it up on the intake seacock, but as the other guys said, there are times when yo might want that seacock closed. So, you'd be better off using it as a "seacock closed alarm" than a starter interrupt itself. One set of alarm contacts, one piezo buzzer, one relay, and of course one fuse. No biggie. $5 project, plus another $10 for the buzzer.
 
#13 ·
The odds are very high the bits are in the exchanger, and as stated above remove the end cap and dig them out.
Highly recommend speed seal. These simple kit allows for a quick and easy impeller change, even upside down and backwards. The latest version has a spinning plate on the faceplate which prevents impeller breakdown even when dry. Here is their website.
Welcome to Speedseal Safety Covers
 
#14 · (Edited)
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.
 
#15 ·
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.
 
#16 ·
All,
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.)


Denise,
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.

BJV,
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,
Ron
 
#17 ·
All,
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.
Ron
 
#18 ·
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.
 
#19 ·
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?
 
#22 ·
...

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.

thanks,
Ron
Ron--

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.

FWIW...
 
#23 ·
Scott,
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.

thanks,
Ron
 
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