How to destroy a new $20K diesel

[DeepFrz]

Great post. Thanks.

Originally Posted by jkishel

1) Not necessarily occurring only while engine is running, could be happening just after engine is shut off, manifold is still hot, raw water is still in the vicinity of the mixing elbow, water boils, salt is left behind.

2) Not a coincidence, number 4 is closest to the mixing elbow, all the water boils off there, none reaches 3, 2 or 1.

3) As salt gradually accumulates, engine performance would gradually decline, but probably not noticeably for a while, maybe a long while.

The precise mechanism of salt deposition is interesting, but unimportant. What is important is that there is too much raw coolant water in the vicinity of the exhaust manifold because the exhaust system is not removing it as needed. The evidence is the salt that is left behind after the water is boiled in the manifold. As long as the anti-siphon on the raw water side is high enough and working, there is simply no other way for salt to get there. One or more of the exhaust system components is blocked, too small or configured to prevent water from being properly removed or to prevent back flow into the engine.

Specifically:

Outlet at stern should be above sea level.

Exhaust hose or gooseneck should rise at least 350mm above sea level.

Waterlock muffler should be directly in line fore and aft with the mixing elbow and be as close to possible and at least 250mm below the mixing elbow (bottom of elbow to water surface inside the muffler). Should provide a high rise mixing elbow if necessary to get the vertical separation.

Waterlock muffler should not be installed sideways across the boat.

Waterlock muffler must be working properly.

Hoses should be in good condition and proper diameter for the engine size.

The closer one can get to meeting these criteria the more likely the exhaust system capacity will be adequate.

[Zingaro69]

Originally Posted by jkishel

1) Not necessarily occurring only while engine is running, could be happening just after engine is shut off, manifold is still hot, raw water is still in the vicinity of the mixing elbow, water boils, salt is left behind.

2) Not a coincidence, number 4 is closest to the mixing elbow, all the water boils off there, none reaches 3, 2 or 1.

*** I agree. I am inclined to believe the problem is at the mixing elbow. ***

3) As salt gradually accumulates, engine performance would gradually decline, but probably not noticeably for a while, maybe a long while.

***one of my biggest puzzles. Engine gave no indication of a problem prior to storing on the hard. I am curious how much the salt could have expanded and crystals grown while the boat sat on the hard for 2.5 years. I don't believe the engine could have run prior to storage in its current state. ****

The precise mechanism of salt deposition is interesting, but unimportant. What is important is that there is too much raw coolant water in the vicinity of the exhaust manifold because the exhaust system is not removing it as needed. The evidence is the salt that is left behind after the water is boiled in the manifold. As long as the anti-siphon on the raw water side is high enough and working, there is simply no other way for salt to get there. One or more of the exhaust system components is blocked, too small or configured to prevent water from being properly removed or to prevent back flow into the engine.

Specifically:

Outlet at stern should be above sea level. ✔ well above.

Exhaust hose or gooseneck should rise at least 350mm above sea level. ✔in excess of 700mm

Waterlock muffler should be directly in line fore and aft with the mixing elbow and be as close to possible and at least 250mm below the mixing elbow (bottom of elbow to water surface inside the muffler). Should provide a high rise mixing elbow if necessary to get the vertical separation. ✔ muffler is on center with the engine block. Elbow slightly to port. 400mm to top of muffler. (Not sure where water level is but below top of muffler)

Waterlock muffler should not be installed sideways across the boat. ✔ inlet to muffler faces directly aft and exits vertically.

Waterlock muffler must be working properly. 🚫❔ presumably so. How would I know? Water and exhaust exit the transom as a mix of burps and mist same volumes as on instalation.

Hoses should be in good condition and proper diameter for the engine size. ✔ engine install certified by Yanmar for warranty purposes.

The closer one can get to meeting these criteria the more likely the exhaust system capacity will be adequate.

S/V Thin Wolf

[Zingaro69]

Question for the inadequate exhaust camp. Once my engine is running again can I adequately test this theory by running the engine, shutting it down and removing the input hose from the muffler to see how much water is there? I'd expect some water but in order to be backing up all the way to the exhaust elbow the hose would have to be full.

Also removing the hose from the top of the muffler to see if it is more than the muffler can hold? I'd expect no water in the hose due to the vertical placement? And water not to the top of the nipple?

Is this a valid test of the theory or is there more to it?
S/V Thin Wolf

[Scout 30]

You need professional advice from a marine diesel installation expert. Have you joined Boatdiesel.com? You might be able to get it from someone there. There's so much guessing going on that it's hard to know what you're getting here.

[hpeer]

Originally Posted by Zingaro69

Question for the inadequate exhaust camp. Once my engine is running again can I adequately test this theory by running the engine, shutting it down and removing the input hose from the muffler to see how much water is there? I'd expect some water but in order to be backing up all the way to the exhaust elbow the hose would have to be full.

Also removing the hose from the top of the muffler to see if it is more than the muffler can hold? I'd expect no water in the hose due to the vertical placement? And water not to the top of the nipple?

Is this a valid test of the theory or is there more to it?
S/V Thin Wolf

You might even be able to do it with a IR thermometer? Don't know, never tried. I would expect the water to retain its temp longer than the air above it.

They are cheap so it might be worth the try.

My gut says you have a pretty good idea of the situation and are unlikely to find someone a whole lot smarter. I think you have the theory sorted out well.

Not that you should not try Boat Diesel, I would.

[jkishel]

Originally Posted by Zingaro69

Question for the inadequate exhaust camp. Once my engine is running again can I adequately test this theory by running the engine, shutting it down and removing the input hose from the muffler to see how much water is there? I'd expect some water but in order to be backing up all the way to the exhaust elbow the hose would have to be full.

Also removing the hose from the top of the muffler to see if it is more than the muffler can hold? I'd expect no water in the hose due to the vertical placement? And water not to the top of the nipple?

Is this a valid test of the theory or is there more to it?
S/V Thin Wolf

There may be more to it than that if this is raw water ingestion while the engine is running (more common with gasoline engines) or the result of transient flow reversal upon engine shut down. Of course, lots of water in the hose between the mixing elbow and the water lock with the engine shut down would suggest that the water lock is small relative to the piping downstream. When you get the engine restarted, the exhaust back pressure should be measured to confirm proper exhaust operation. Check engine specs for max. back pressure, should be less than about 2 psig without excessively high fluctuations (exhaust pressure fluctuates as slugs of water are discharged from the system). A diesel mechanic should evaluate the back pressure readings. A water lock can be tested for internal leaks by filling the upper chamber, it should take about half the total volume of the cylinder before water begins to flow from the inlet.

[hpeer]

Here is a wild speculation....

Could you be getting water VAPOR back into the engine thought the #4 port? Then the salt is paripitating out. In short, do you have a little still working there?

Engine shuts down. Water in hose runs back to water lock.

Enough height to exhaust run that there is some small amount of residual pressure in the line, on the engine side of the water lock.

It pushes water up the run from the water lock towards the engine.

If the engine has stopped with the #4 port open, water vapor from water will seep back toward that piston.

Alternative...water left in hose between water lock and engine evaporates, 4 port is open, allowing water vapor through.

Then salt condenses out.

Don't know if that makes any sense?

[hellosailor]

Sure sounds like what I would think fits the criteria. Some plumbing changes for volume and heights might help. Including a way to ensure the hot seawater was cooling down further away from the engine, or faster. (Maybe replacing the first run of "steam hose" with metal pipe instead, to encourage faster cooling as well?)

[Terra Nova]

Zing--where is the waterline as compared to the photo of your engine/exhaust?

[hpeer]

My Mark I eyeabll says its below the water line. If this DWG is to be believed.

Also there is some weird thing shown hanging off the back of the engine.

It almost looks like a water lock mounted up high. Hard to belive that is what it is.

[Cheechako]

Originally Posted by hpeer

Here is a wild speculation....

Could you be getting water VAPOR back into the engine thought the #4 port? Then the salt is paripitating out. In short, do you have a little still working there?

Engine shuts down. Water in hose runs back to water lock.

Enough height to exhaust run that there is some small amount of residual pressure in the line, on the engine side of the water lock.

It pushes water up the run from the water lock towards the engine.

If the engine has stopped with the #4 port open, water vapor from water will seep back toward that piston.

Alternative...water left in hose between water lock and engine evaporates, 4 port is open, allowing water vapor through.

Then salt condenses out.

Don't know if that makes any sense?

Sounds good to me!

[Cheechako]

Originally Posted by Zingaro69

Question for the inadequate exhaust camp. Once my engine is running again can I adequately test this theory by running the engine, shutting it down and removing the input hose from the muffler to see how much water is there? I'd expect some water but in order to be backing up all the way to the exhaust elbow the hose would have to be full.

Also removing the hose from the top of the muffler to see if it is more than the muffler can hold? I'd expect no water in the hose due to the vertical placement? And water not to the top of the nipple?

Is this a valid test of the theory or is there more to it?
S/V Thin Wolf

YES.

[Moody guy]

Originally Posted by hpeer

My Mark I eyeabll says its below the water line. If this DWG is to be believed.

Also there is some weird thing shown hanging off the back of the engine.

It almost looks like a water lock mounted up high. Hard to belive that is what it is.

Hi hpeer
Weird thing could be a dry exhaust riser in metal pipe then water is injected at the top of this then rubber pipe exhaust from there.
My old Elizabethan had that setup.
Don't think the original poster has that.


Sent from my iPad using Cruisers Sailing Forum

[Wotname]

Originally Posted by hpeer

Here is a wild speculation....

Could you be getting water VAPOR back into the engine thought the #4 port? Then the salt is paripitating out. In short, do you have a little still working there?

Engine shuts down. Water in hose runs back to water lock.

Enough height to exhaust run that there is some small amount of residual pressure in the line, on the engine side of the water lock.

It pushes water up the run from the water lock towards the engine.

If the engine has stopped with the #4 port open, water vapor from water will seep back toward that piston.

Alternative...water left in hose between water lock and engine evaporates, 4 port is open, allowing water vapor through.

Then salt condenses out.

Don't know if that makes any sense?

No, sorry, it doesn't make sense.
The water vapour will not contain any salt.

Water will become 100% water vapour once it reaches 100 C (or higher). I'm not sure when NaCl will become salt vapour but it many many times higher than that.

However, there will be plenty of salt left behind wherevever the water becomes vapour

[FlyingCloud1937]

Did you read Tonys TIPS????

Originally Posted by FlyingCloud1937

Well clearly there is a problem, If you don't want the same problem after it goes back together, then you better change something.
Start by reading and understand Tonys exhaust tips.
Tony's Tips - Information about Marine Diesel Engines and Boats from Tony Athens

I'll guarantee you its your setup, I would never install as your is.

Lloyd

Originally Posted by 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