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Old 06-10-2019, 08:27 PM
ernst ernst is offline
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Question Motor died. Two mysteries. Is it the snap ring on the impeller?

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?
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