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I've long advocated a means of draining the system. And a dagger board type valve at the transom.I originally had a ballvalve on the bottom of the muffler,then a pullcable to the helm Then I installed a solenoid operated valve (normal open) triggered by oil pressure switch.Dumps to bilge .Takes all the guess work out. For heavy seas the stern valve is a must. Any water surging forth and back can up and over and eventually fill any standpipe causing full fill of engine.Besides, up here in the cold and damp, air blowing thru the system while shut down talks directly to which ever exhaust valve is open (hint ,, RV type black water valves are 3 ")
 

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You do not determine seawater in oil by testing for sodium. There are additives in both coolants and oil that are sodium based. The lab should have known that, it is basic.

Test for inorganic chloride. This can be done by any of several simple methods, including test tapes. Inorganic chloride is corrosive, is NOT used in any additive package, and is generally limitied by specification to about 5 ppm. Seawater is >25,000 ppm chloride.

Simple.

Do not test for total chloride; some few diesel oils contain chlorinated parifins, though this is only ship and locamotive oils. No common diesel oil contains chlorinated parrafins.
 

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Discussion Starter · #63 ·
If I am reading this correctly, you have no riser connected to the exhaust manifold? I made this same mistake when I replaced my exhaust system. Last year I added the riser and have not had an issue since.
Good idea, but no room for it in the engine space. A large day tank sits directly above the exhaust elbow.
 

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Discussion Starter · #64 ·
Test for inorganic chloride. This can be done by any of several simple methods, including test tapes.
I'll see if I can find these in the souk in Casablanca. :rolleyes:

One of the challenges of cruising in far away places is that many of the resources we take for granted in the US are, if not unknown, quite often unavailable.
 

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It has been an interesting thread. I come away from it thinking the engine needs a riser, and that the head gasket narrowly missed failing from the overheating. Maybe because the engine is new, but anyways, torqueing again the head bolts, wouldn't hurt. If just one bolt needs 10 more pounds of torque, it would be worth the effort.
 

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Discussion Starter · #66 · (Edited)
It has been an interesting thread. I come away from it thinking the engine needs a riser, and that the head gasket narrowly missed failing from the overheating. Maybe because the engine is new, but anyways, torqueing again the head bolts, wouldn't hurt. If just one bolt needs 10 more pounds of torque, it would be worth the effort.
I've mentioned torqueing the head bolts to three Yanmar mechanics in three countries. They all said it's not necessary. I point out to them that the engine's op manual suggests it. They just smile and shake their heads.

It's been very strange, but all the mechanics I've dealt with have been reluctant to take my money. None have wanted to tear the engine apart looking for leaking gaskets or even loose head bolts. I think it's like doctors not wanting to over-treat the patient.

A leaky head gasket would lead to coolant loss. As I mentioned above, I've been watching the coolant level very closely for the last month. The amount of coolant consumed by 50 hours of operation is a fraction of an ounce and all the mechanics encountered so far tell me that amount of coolant loss is not significant. Evidence suggests it's not a coolant leak.

As for a riser....we'll have to try the easier solutions first. Creating space for a riser would require a big reconfiguration of the engine space (moving the day tank, raw water and fuel filters, fuel pumps, etc). I'd like to exhaust the simpler (and cheaper) alternatives first and use frequent oil changes to minimize the damage to the engine in the mean time.
 

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Bill, how old is your boat? Old enough to have a re-power done to it. My 1969 Bristol engine is at or below the water line. The old exhaust was not a wet exhaust and needed no riser. The pipe was a one piece, double walled brass pipe. Exhaust in the inside pipe and water in the outer jacket. See attached picture. The hard mounted engine and one piece exhaust pipe must had been installed as the boat was built around it. When I rebuilt the engine, the exhaust pipe was not serviceable. I had to remove it in three pieces. The reason I rebuilt the engine was because I got a hole in the exhaust pipe, water into the exhaust and back siphon into the engine. I replaced the system with a wet and did not do the riser, the riser was needed as well as a siphon break elbow just before the water goes into the exhaust. You can see that item in the last pictures.

So, one of two things for you to ponder...what was your old exhaust system and do you have the siphon break elbow?


 

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On most diesels overheating= blown head gasket. Heat exchangers are less of a victim. Turbo driven diesels probably have more durable gaskets that can take the higher pressures and temperatures. The down side is that the turbo needs a cooling down period, to be bathed in freshly pumped oil, or the bearings cook from oil starvation, after shut down.
Sea air is laced with salt. Volumes were compressed, far more than any normally aspirated engine, ignited, and then the same oil washed the salt mineral deposits for over 200 hours. That could be enough to get the readings you had.
 

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I'll see if I can find these in the souk in Casablanca. :rolleyes:

One of the challenges of cruising in far away places is that many of the resources we take for granted in the US are, if not unknown, quite often unavailable.
True enough. Just pointing out that the correct chemical test for seawater is not sodium, it's chloride, and the test is much easier than metals. Any oil lab should be able. I'm guessing corrosion (fine pitting) on the dip stick might also be evident; seawater is rough on plain carbon steel.
 

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UPDATE:

When we arrived in Lagos, Portugal I invited yet another Yanmar mechanic aboard for a consult and another oil analysis in a local lab, results of which aren't back yet.

Since the last oil change I've stopped using the Gori overdrive and have been tracking the coolant level religiously.....in 50 hrs we're down only 1-2mm in the overflow bottle. The mechanic says that's not unusual.

Conclusion: it's not a coolant leak.

If it isn't coolant, it's got to be seawater. There are three sources of seawater: the oil cooler, the air cooler and the exhaust system. We tested the oil cooler and it's good. That leaves two possibilities.

The mechanic in Lagos took a hard look at the exhaust system and he thinks the problem may lie there. I have since done an analysis of the volumes of the hose runs and the muffler and have reached the conclusion that he's probably spot on.

When the new engine was installed it required that we increase the size of the exhaust lines from 2.5 to 3 inch hoses. The larger hose was stiffer and required installation of hard fiberglass elbows in a couple of places where the turns were tight. With those exceptions, the general layout of the old exhaust system was followed in terms of the hose runs.

Exiting the exhaust elbow we now have a 90 deg elbow and then 20" of hose to the water lift muffler (side in, top out). We have a 28" vertical rise coming out of the muffler to a 90 deg elbow and then a 5+ ft horizontal run aft to the steering compartment where the hose loops up to the top of the space and then drops to the exhaust port on the transom. In all, there is probably 9-10 feet of hose between the top of the muffler and the highest point in the exhaust hose run plus the ~ 2 feet between the exhaust elbow and the muffler.

The new engine was actually smaller than the old one (despite the ~2x HP) and so the height differential between the exhaust manifold and the muffler has decreased by a few inches, and due to the new 3" very stiff hose we need for a 90 deg. elbow immediately below the exhaust elbow -- all of which means that the angle of the hose running to the muffler is much shallower than with the old engine. My estimate is that it's a 8-10" drop from the exhaust manifold to where the hose enters the muffler, and that the hose is 10-15 deg off horizontal.

Less height differential + shallower angle = higher potential that we end up with seawater in the hose between the muffler and the engine IF the muffler fills with water when the engine shuts down.

Enter the new 3" hose -- larger diameter = greater volume of water in the hose and greater chance that the muffler has more water in when the engine shuts down.

Based on the calculations I've done of the volume of the hoses and the volume of the muffler, and using assumptions for the gas to water ratio in the hoses provided by Centek and Vetus tech support (Estimates range between 25 and 50%)....I've come to the conclusion that the muffler is overfilling (it should be no more than 1/2 full after shut down according to the tech guys).

Over filling the muffler puts standing water in the hose between the engine and the muffler when the engine is shut down. Now put the boat in a big following sea like we had crossing he Atlantic last summer and you now have water sloshing about in the pipe between engine and muffler with the potential for a few sloshes pushing small quantities of water up to the top of the exhaust elbow and into the exhaust manifold and from there a few drops get into the cylinders with open exhaust valves. It doesn't take a much water to register ppm of salts the oil. It's certainly not enough water to interfere with the starting of the engine. And, of course, once the engine starts the few droplets of salt water are immediately evaporated within the cylinder and hence no sign of foreign liquid in the oil.

So, the current hypothesis is the salts are from seawater entering the engine through the exhaust due to overfilling of the muffler, caused to long hose runs and larger hose.

With the approach of the fall season I need to move the boat further south and so we will not have time to address a redesign of the exhaust system before moving on from Portugal. We're moving on to Morocco next week (only 200 miles) where tech support and suitable parts are probably in short supply. We have some down time in Morocco and , my interim solution will be to install a small ball valve in lower part of the muffler which will enable me to drain the muffler into the bilge after shutting down the engine when at sea. I'm also going to install a flapper on the exhaust as a preventive measure until we sort the entire system out.

We will run with these two changes to the system and continue to change the oil every 50 hours until we can be sure that we've found the problem. My guess is that draining the muffler following every engine shut down will solve the problem....but that remains to be seen.

Stay tuned.
Sounds like your analysis is good. If, as Delta suggested, you don't have a riser out of the exhaust manifold, It wouldn't hurt to install one, even something temporary. Anytime something is changed there is always the possibility for problems. I am surprised your engine installer would put the engine in without a riser?

Not sure if I followed your description of the plumbing properly? Maybe pictures or a drawing?

Paul T

Edit: Oops, didn't see your post #63 Maybe a riser "loop" higher than the manifold somewhere in the system?
 

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If it is coolant - test the oil for glycols
If it is seawater - test the oil for free chloride.
Seawater can be taken up by the engine through air intake, which seems likely in your case since there is no evidence for coolant or direct seawater intrusion. It only takes a small amount of spray in the air to turn into salts in oil. Have you checked your fuel tank for seawater intrusion?
In any case, the concentration of salts in oil has to be compared to a benchmark set for engines operating in marine environment.
 

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Have you checked your fuel tank for seawater intrusion?
This is a good idea, I don't think it would take a whole lot of salt water in the fuel tank to show up in the oil. How are deck fill seals? You may not have much in it now, but perhaps the last few tanks have diluted it.
 
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