How to destroy a new $20K diesel

[SkiprJohn]

You have my sympathy. That truly is a shame.

[Zingaro69]

So I'll try and address all these issues. It is water cooled and if the raw water was cracked in the exchanger it would leak into the fresh water.

We did flush it by filling the bucket as it was drawing it up. The engine was then shut down.

This is a center cockpit boat with the engine below the cockpit so there really is no other option to run the exhaust to the back of the boat. That house is much longer than you see. After it runs up in thepicture it then has to run along the hull through the aft stateroom before exiting. The exhaust hose doesn't move that much water so what ever comes back down when the engine shuts off should be held by the water lock. *** I don't have in my mind a clear understanding of how the water lock works. Can someone explain it to me? I thought that hydrostatic pressure would keep it from back flowing even if there's more water from the exhaust hose than the lock could hold. Isn't that the principle it "locks" the water out?

The exhaust exits the elbow and then runs directly under the engine forward to the water lock which is also below the engine. It would have to fill all that hose as well before backing up to the elbow.

S/V Thin Wolf

[Zingaro69]

It doesn't make sense. This engine shouldn't have been running when I hauled out. The salt completely obstructed #4 exhaust port all the way back to the elbow so the entire manifold was obstructed. The engine couldn't breathe.

Look at the elbow on the ground. It points down when installed at approximately 45°. The exhaust exits through the center and raw water is injected around that collar and mixes as it goes down and out. Gravity should prevent it from going into the engine. What I'm curious about is when the engine shuts down some raw water still comes down and hits that hot inner exhaust collar. If it turned to steam it would rise into the manifold rather than down the exhaust hose. Now steam is pure water distilled but it would leave salt behind. Can/is that salt creeping up into the manifold? If that were the case and this was a poor design wouldn't all these Yanmar's have a similar problem?

S/V Thin Wolf

[Zingaro69]

My problem is I don't know why this is happening so I don't know how to prevent it happening again. 😦😲

S/V Thin Wolf

[Old Swampy]

There is a lot of talk about "water lock" in the muffler. Water will back up into the engine, if the engine doesn't start and you run the starter long enough (water will have to accumulate in the exhaust hose as high as the exhaust manifold). That is not because of "water lock." Likewise, if you pump water into the exhaust pipe at the stern of the boat, it will fill the muffler, exhaust manifold, and any cylinders with open exhaust valves. Now, the pistons can't compress the water. Perhaps this should be called "water locked."

[DeepFrz]

Is there any chance someone swapped parts with you or even the whole engine? How secure is the yard you are in? You are absolutely correct that the engine would never run like that. You flushed with fresh water so the salt didn't build up while your boat was on the hard. New engine, why is the compression low? Good luck.

[jongleur]

Recommend if you are unfamiliar with water lock/
water lift/accumulator, you talk to someone at
Vetus.com.

It looks like your setup allows plenty of opportunity
for water to regularly back up into your engine.

[Exile]

I'm not sure this amounts to an analogous incident, but my Westerbeke 82B suffered what sounds like a similar fate a few years back. I purchased the boat in 2007 with only about 600 hrs. on the engine. Put another 600 hrs. on it over the next few years without incident. Had a 1000 hr. service professionally done before sailing it from Miami to Annapolis where I had planned to leave it on the hard over the winter. When I went to have the boat winterized, the engine wouldn't turn over. Turned out that salt water had infiltrated cylinders 3 & 4, and completely seized #4.

So again -- no inkling of any sort of problem all the way to the dock in Annapolis. Boat sits on the hard for several months. Engine then found to be seized. WTF??

When there was no alternative but to replace the engine, it turned into a large insurance claim due to the expense of getting the engine out of the boat, etc., and the most likely cause was ultimately determined to be a design defect in the exhaust system. The ins. co. surveyor ruled out any snafu with the winterization process, and also ruled out seawater backing up from lengthy engine cranking with the r/w intake seacock left open. Instead, he concluded that a "fine mist" of salt water had been back siphoning into the engine over a long period of time, and the last trip which involved a lot of motoring -- immediately followed by a lengthy lay-up -- had finally been enough to ruin the engine.

It turns out that when the prior owner had upgraded the original 70hp Westerbeke with the 80hp one, the dealer who did the install had neglected to also upgrade the exhaust hose with the larger-spec'd ID hose. The muffler itself was also not replaced, and may have been undersized as well. The entire episode was quite a shocker given the engine's low hrs., and considering it had given no warning that anything was wrong until it had completely failed.

[Scout 30]

Water lock can mean 2 things in this instance. Water lock or hydro lock occurs when water gets into a cylinder. Diesels create combustion by compressing air & fuel. However, they cannot compress water so the motor locks up.


Some mufflers are called water locks because they block the water from back flowing into the engine.

[Mirar]

When I see all that winding hose c/w huge course changes I firstly think of all that induced backpressure in the system. That is before the exhaust even gets to start its journey aft. I can't imagine how that design ever worked to begin with.
On our new build there was no place to route the 3" hose out the transom even though the engine is right in the stern. I followed Dave Gerr's design suggestions for the "northsea" exhaust which involves running the exhaust out port and starboard. It has many advantages in that it reduces that tendency of the stinking fumes wafting up the sugar scoop into the cockpit, totally eliminates backpressure in that if one outlet is slightly submerged the other side is well clear and it greatly reduces the length of hose run.
His book "Boat Mechanical Systems Handbook" is full of excellent ideas for a proper installation.
Greg

[Cheechako]

That system doesn't look non typical for a CC boat. There is usually a lot of hose running aft... except when an owner has bit the bullet and shortened it to a side exit. When the engine runs there isn't a lot of water in the hose. What is there should be held by the muffler when turned off. The hard part is predicting how much there is.... so your muffler can be sized appropriately.
I cant see the pictures presented well enough to tell what is going on... but cant see any "totally blocked with salt" from what I can see. I guess due to the pics.
It's a strange deal for sure.
If I am seeing it right, the exhaust enters the side of the muffler and exits the top. It is my understanding that the exhaust should enter the tube on the muffler that does not extend into the water sitting in the muffler. If I were you I would check if that is how yours is set up. I'm not sure it matters, but it may.
In other words, if it was a muffler with two tubes on the top, you want the engine exhaust going into the short tube which doesn't extend to the bottom of the muffler.

[Terra Nova]

Correct, the outlet is the deep tube.

The problem, as I said, is in the ridiculously long and horizontal routing. It must rise vertically from the muffler to the highest point in the system.

[Cheechako]

Yeah... but a lot of CC's have that routing... although going under the engine and having the muffler in front adds a bit more... maybe 3 ft.... Something just doesn't add up in this whole thing...

[FlyingCloud1937]

To figger the amount of potential water in the exhaust hose, measure the total length X's the ID / 3.14 = cubic inch / 231 = gallons. Now consult the muffler size.

The horizontal portion after the the lift is a deal killer as mentioned, it will hold and collect water, which will cause back pressure. Use a manometer to measure the back pressure.

The water lock muffler is the reverse of a water pipe, if this is also hooked up wrong, it could flood the engine when sitting.

For salt to crystallize in the manifold, it would have to be present when the manifold exceeds 135 F.

Lloyd

[FlyingCloud1937]

Also, what is that Tee with the small hose to/from on the Anti Siphon? And to which side of the is it in or out?

It mos definitely should not be there.

Lloyd