How to destroy a new $20K diesel

[Zingaro69]

So the boat has been on the hard since May 2012. When we hauled out I had the engine flushed with fresh water because I didn't want to leave it with salt water in it. It wasn't supposed to sit on the hard this long we hoped to be back in 8 months. I string of surgeries between both of us old farts pushed us back this long. A normal amount of water was pumped out with the exhaust both prior to haul out and during flushing out on the hard. *I didn't notice the engine running hard, always started easily, ran at least every other day and it never overheated.*


I'm still not sure how/why exactly the water is backing into the exhaust. *With the manifold completely obstructed I don't understand how the engine ran to get me here. I still don't understand how that much salt builds up in the exhaust manifold with out flooding the cylinders. I don't know how this engine ran at all.*
When we put her back in the water she wouldn't start, had poor compression, and this is what we found.*


Thanks for any advice.




S/V Thin Wolf

[Zingaro69]

*I'll start with the setup of the design.

The water block is mounted beneath the engine on the bilge exits vertically to the exhaust.

Because it's a center cockpit boat the exhaust has to run up and out to the back and out the back of*the transom.

Water exits heat exchanger up through the anti siphon and comes back down to the exhaust elbow.



S/V Thin Wolf

[Zingaro69]

When we removed the heat exchanger/exhaust manifold this is what we found. *The salt is packed solid in #4 exhaust port all the way back to the exhaust elbow.*

This is all the salt we chipped out of the manifold.*

There was some salt on top of the pistons and a lot of sludge. We have poured some oil on top to soak down the rings.*

S/V Thin Wolf

[Zingaro69]

Tried to have the valves and seats machined but too damaged and replacing the valve set.*


The injectors were fouled obviously and have been serviced and adjusted.*



S/V Thin Wolf

[Zingaro69]

A normal amount of water was pumped out with the exhaust both prior to haul out and during flushing out on the hard. *I didn't notice the engine running hard, always started easily, ran at least every other day and it never overheated.*


I'm still not sure how/why exactly the water is backing into the exhaust. *With the manifold completely obstructed I don't understand how the engine ran to get me here. I still don't understand how that much salt builds up in the exhaust manifold with out flooding the cylinders. I don't know how this engine ran at all.*
When we put her back in the water she wouldn't start, had poor compression, and this is what we found.*


Thanks for any advice.



S/V Thin Wolf

[Zingaro69]

This is the engine.

S/V Thin Wolf

[44'cruisingcat]

Wow sorry to see that damage to your new engine.

Friends of ours had their boat's exhaust blocked up by mudwasps, which resulted in similar damage. That was an old engine though, and an infrequently used boat.

[ErikFinn]

How old is that engine exactly?

Isn't that just carbon in your exhaust manifold ports? Looks black but maybe I'm missing something..
The engine looked like a Yanmar; you know they should be run hard periodically to burn off the carbon? I supposed quite the same with any diesel, but especially so with the high revving Yanmars.

The exhaust elbow (which I believe is depicted in one of your fotos) can be considered regular maintenance parts. yes they do collect salt and do not last forever.

If you really think you are getting seawater into the exhaust manifold I would suspect the exhaust hose and the raw water intake installations, maybe worth getting a professional to take a look at those, cooling seawater should not be able to flow and enter the exhaust manifold...

[bletso]

I had a lift can problem a few years back and fortunately caught it early. i. e . water in exhaust tube at the manifold. Caught it because I use a cheap flexible coupling from manifold to muffler/lift can assembly.

[Zingaro69]

There is some carbon blackening the surface of the salt but that is all salt. The elbow itself looks fine, a fair amount of carbon but with what the engine appears to have been through I'd expect some carbon built up. Prior to hauling out the engine ran 10 hours a day for ten days straight at about 6-6.5 knots. I had no wind the last ten days and was forced to motor through the Philippines. It's a miracle it didn't leave me stranded. But like I said it didn't give me any indication it was struggling. I.e missing or backfire etc.

The engine was installed in 2010 but has been on the hard since May 2012.

I don't understand how that much salt could obstruct the manifold without flooding the engine entirely. It doesn't look like it could have run.

S/V Thin Wolf

[Zingaro69]

Erik the raw water and exhaust mix at the exhaust elbow but I agree it shouldn't be able to get in there.

S/V Thin Wolf

[Scout 30]

When you say you had the engine flushed with fresh water how was that done? Was the system hooked up to a hose?

[a64pilot]

Originally Posted by Scout 30

When you say you had the engine flushed with fresh water how was that done? Was the system hooked up to a hose?

Makes you wonder if it was flushed like an outboard, you know, without the engine running?

[SkiprJohn]

Sorry about the mess. A64pilot has a good question. If freshwater had been flushed through the system then there is no way that salt water could get up there while you were on the hard.

[a64pilot]

Actually what I was suggesting was the possibility that nothing was wrong, until the engine was filled with water during the "flush".
I believe if you hook a hose to the raw water side and just flush water through the engine like you do with a modern 4 stroke outboard, you will fill the engine with water.

Pure specualtion, but as it was running fine and had several hours recent running, it seems at least possible.

I believe it's possible that the salt could be aluminum oxide, corroded aluminum looks a lot like salt?