Motor died. Two mysteries. Is it the snap ring on the impeller?

[ernst]

Haven't been here for years which shows how well my A-4 works! But on Saturday this streak ended. Fortunately nothing too dramatic but I need to know what is going on.

Here is some history: Many years ago, I installed the Indigo freshwater cooling system (the original one, the one that re-purposes the original water pump for the coolant and adds a new mechanical one for raw water). A week ago, I checked both impellers. Both looked fine but I lost all the coolant and I replaced it.

So, the main story: I sailed Saturday (great sailing on the Chessie!) and was approaching my selected anchoring spot. I was just getting out the leather gloves for the anchor chain when the motor stopped! No hesitation, just stopped. I dropped anchor immediately (it was a reasonable spot to stay for the night) and I investigated. So here are the symptoms:

First, a non-symptom: the impeller looked perfectly fine.

Second, I noticed that the coolant hoses leading to and from the coolant pump were reasonably cool, probably cooler than normally (I don't have a good basis for comparison because it always worked so well that I never really paid attention). OTOH the one that comes out of the block to the exhaust manifold was much hotter.

The other symptom is that the coolant level was way low! I ended up adding 3 quarts of water, even though I had refilled it a week ago (using the procedure in the Indigo instructions: loosening the hose at the coolant pump, run it until the coolant gets warm, then loosening the hose at the TCV and getting to 180degrees). All as prescribed. When I was done with it, it should have been filled to the brim.

Of course, I could have a leak somewhere. But if that is the case, where did the coolant go? It is not in the bilge! The thought that the head gasket might have blown and the coolant ended up in the oil crossed my mind but when I pulled the dipstick, the oil looked fine. No emulsion or anything.

So, there are two mysteries: One is the disappearance of the coolant. The second is why the motor stopped. Does it do that if it overheats? It was not glowing hot, just a bit warmer than I would have expected after running it for ~1/2 hour. Any ideas?

To come to the last part of my subject line: When I checked on the impellers last week, I remembered that I had read somewhere on the internet that the snap ring (circlip) on the impeller is there only for shipping purpose. Since it is a bit of a pain to take it off and on again (if you don't have the appropriate tool handy). I took it off and THREW IT AWAY.

Was that a big mistake? Is the snap ring functional after all? Did the coolant pump just not pump and therefore there was no circulation in the block?

Anyway, I waited overnight and in the morning the motor started immediately! I did not dare to run it for a long time, only to get off the anchor, and then I sailed the boat right to the marina where I ran the motor again for 5 minutes to get into the slip. Again flawlessly.

Any ideas?

[ndutton]

I think you're headed down the right path for the most part. Coolant loss is the most likely cause of your elevated temperature and there are very few places the coolant can go:

1. Leak out and end up in the bilge - not in your case
2. An internal block breach into the crankcase - also not in your case
3. Manifold breach sending the errant coolant out the wet exhaust (who would even notice?)

Therefore I suggest a manifold pressure test is in order.

For the shut down I would approach it as separate from the elevated temperature. Testing is best performed at the time of shutdown and the first determination is spark or fuel. Once that is known the real troubleshooting can begin.

[ernst]

I think you're headed down the right path for the most part. Coolant loss is the most likely cause of your elevated temperature and there are very few places the coolant can go:

1. Leak out and end up in the bilge - not in your case
2. An internal block breach into the crankcase - also not in your case
3. Manifold breach sending the errant coolant out the wet exhaust (who would even notice?)

Therefore I suggest a manifold pressure test is in order. As for the impeller retaining clip, it's not part of your current troubles and in my opinion completely unnecessary in use.

For the shut down I would approach it as separate from the elevated temperature. Testing is best performed at the time of shutdown and the first determination is spark or fuel. Once that is known the real troubleshooting can begin.

Huh! This is something I had not considered!

On the one hand, I can't help thinking that there is a connection between me opening the cooling system, refilling it etc and the motor overheating a week later (with no use in-between). OTOH, maybe there is such a thing as a pure coincidence and your option #3 surely would explain the loss of coolant. So I agree, a pressure test of the manifold may be in order. I found your helpful thread http://www.moyermarineforum.com/foru...ad.php?t=10146 and will procure the doohickey you are recommending.

I will also see if I can reproduce any of the symptoms while safely moored in the slip. Will dig out my IR thermometer and find out if the temperatures of the coolant going into the block and coming out of the block are too far apart. I don't really know what to expect there, clearly it must heat up but I never really paid attention to it. If anyone has an idea what is a reasonable temperature difference, I am all ears.

And thank you for alleviating my concerns about the snap ring. On the one hand, it would have been an easy solution. On the other hand, I would have felt incredibly stupid having thrown it away

As for why it stopped, again it could have been a pure coincidence that that happened when the motor ran our of coolant. But at some point there is too much of a coincidence....

Anyway, thanks for the information. I will report on the outcome of my tests but I can only get to the boat on weekends so it will not be a superfast process.

[roadnsky]

I was just getting out the leather gloves for the anchor chain when the motor stopped! No hesitation, just stopped.

So, there are two mysteries: One is the disappearance of the coolant. The second is why the motor stopped.

Anyway, I waited overnight and in the morning the motor started immediately!

Ernst-
Did you try to restart the engine once you were anchored?
If so, did it start or what?
Or, did you wait until the next morning?

[ernst]

Ernst-
Did you try to restart the engine once you were anchored?
If so, did it start or what?
Or, did you wait until the next morning?

I tried to start it immediately. I did not want to empty the battery so I did not turn if over a lot but I gave it an honest try. It did not start.

Next morning, it started immediately, without the slightest hesitation (as it has done for years).

[Peter]

When I was done with it, it should have been filled to the brim.

Is it possible that you did not get it filled to the brim? I have read many posts abut the challenges of getting all the air out of these FWC systems.

Did you measure how much coolant you added? Others with experience with these systems may have some idea of the system volume.

Peter

[roadnsky]

I tried to start it immediately. I did not want to empty the battery so I did not turn if over a lot but I gave it an honest try. It did not start.

Next morning, it started immediately, without the slightest hesitation (as it has done for years).

...the motor stopped! No hesitation, just stopped.

Are you points or EI?
(Maybe you see where I'm going?)

[ernst]

Is it possible that you did not get it filled to the brim? I have read many posts abut the challenges of getting all the air out of these FWC systems.

Did you measure how much coolant you added? Others with experience with these systems may have some idea of the system volume.

Peter

Yes, that thought did cross my mind. I tried to follow the instructions from Indigo but it is possible that I missed something.

I know how much I added, about 3 quarts. But I don't really know how much I lost in the bilge when checking the impeller. You make an excellent point.

[ernst]

Are you points or EI?
(Maybe you see where I'm going?)

Points.

(actually I am not sure where you are going. What does my answer tell you?)

[Dave Neptune]

I suspect both a breech in the manifold AND an intermittent coil, they fail when they get hot and "cook" if the key is left on.

Dave Neptune

[roadnsky]

actually I am not sure where you are going....

an intermittent coil, they fail when they get hot and "cook" if the key is left on.

What Dave said

[ernst]

What Dave said

I don't understand what is cause and effect. The motor was running and it then stopped. Why would the coil get cooked then? I turned it off immediately, within maybe 10 seconds. I have a pretty annoying low oil pressure alarm so the ignition is never on for more than a few seconds without the motor turning.

[ndutton]

I think the guys are correlating the symptoms as presented to a common conclusion often repeated in the past. A coil overheated to the point of damage will fail but somewhat miraculously appear to temporarily heal itself when it cools down. Their suggestion is not conclusive but rather something to explore. With the new information that you have an oil pressure alarm that provides a reliable reminder to switch off the ignition when the engine is not running, the overheated coil possibility, although not entirely off the table, is less likely.

We don't even know for sure yet if the shut down was fuel or spark related.

[ernst]

Ah, that makes sense!

And I agree that there is not enough information. I am planning for the weekend to

(a) purchase the equipment for an exhaust manifold pressure check and do the test

(b) make sure the coolant system is full, at least the main reservoir and overflow container

(c) run the motor for a while (an hour?) under load in the slip and take a series of temperature measurements at different locations: at the coolant pump, hose from motor block (head) to exhaust manifold, hose exiting exhaust manifold

(d) after running the motor, check coolant level again.

That should provide some data, right? Anything else I should do?

[Dave Neptune]

Ernst, when you shut it down check the spark again to be sure it is still the "snappy blue" spark you started with. Check it cold and keep the stuff around so you can again immediately after running.
RE the running duplicate it as much as possible by keeping the engine hatch closed except for "momentary" monitoring.

Dave Neptune