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Yanmar Diesel Smokes

Old 08-02-2020, 02:16 PM
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Default Yanmar Diesel Smokes

I have two questions.

1. I am looking to purchase a boat and would like a recommendation for a Yanmar diesel surveryor/mechanic near Venice.

2. Why would engines smoke?

It has two Yanmar 6LY-UTE they begin smoking when you hit about 1800 rpms? Air cleaner is dirty, engines a little dirty and soot in engine room. Motors run good and sound fine, although I saw them they had already been started earlier that day so I do not know how they start when cold.

Boat is part of estate as of January and was last used around thanksgiving 2019. Prior to that is was used every two to three months for a week at a time. Appears to have been well maintained.

Thanks for the input.
Old 08-02-2020, 04:15 PM
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From what you just said, the engine can't breathe. I don't have a yanmar but my diesel will smoke with a dirty air filter. Engine could be overloaded, a number of reasons. I would definitely have someone look at it.
Old 08-02-2020, 04:15 PM
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There are endless reasons for a diesel to smoke.

1800 RPM's at the dock or under load?

Is the bottom clean?

Is the smoke from both motors?

What color is the smoke?

Does performance change?

"Air cleaner is dirty, engines a little dirty and soot in engine room". Assuming this is a statement then you have potential answers in two of those, air cleaner and soot in ER (exhaust leak)

What do the fuel filters look like? How old is the fuel?
Old 08-02-2020, 04:53 PM
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As he said, soot in the engine room is an indication of an exhaust leak. Have mechanic check exhaust manifold gaskets. This will also cause the air filter to be dirty. Clogged air filter means not enough air getting into engine.
Old 08-02-2020, 06:30 PM
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Weak turbo
Old 08-02-2020, 06:54 PM
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Originally Posted by Hjudge49 View Post
As he said, soot in the engine room is an indication of an exhaust leak. Have mechanic check exhaust manifold gaskets. This will also cause the air filter to be dirty. Clogged air filter means not enough air getting into engine.
Exhaust leak before the turbo will cause all of this.
Old 08-03-2020, 05:56 AM
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Originally Posted by lovemydog View Post
There are endless reasons for a diesel to smoke.

1800 RPM's at the dock or under load?

Is the bottom clean?

Is the smoke from both motors?

What color is the smoke?

Does performance change?

"Air cleaner is dirty, engines a little dirty and soot in engine room". Assuming this is a statement then you have potential answers in two of those, air cleaner and soot in ER (exhaust leak)

What do the fuel filters look like? How old is the fuel?
I am looking into purchasing this vessel, I have asked most of these questions.
I did not drive the boat, it was picked up by a gentleman who brought it to this location to sell. He told me it began to smoke when under load at about 1800. So at that point he traveled at about 6-8 kn.
He had someone come to clean the bottom who reported it was not clean and he is coming back for a second cleaning.
Smoke is from both motors.
Smoke was black.
I cannot say about a performance change as I didn't ask, only that when he saw smoke starting he throttled down.
Exhaust leak seems like the most likely root of the problem. Not sure why I was not seeing this.
I do not know what fuel filters look like. Fuel is likely from October/November 2019. I was told by seller's agent (the gentleman that drove it to current location) previous owners used it frequently when they were in FL. He also said they were not down during Thanksgiving/Christmas and they passed in January. He has gathered information from previous neighbors and family.

Thank you for the input.
Old 08-03-2020, 05:58 AM
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Originally Posted by Hjudge49 View Post
As he said, soot in the engine room is an indication of an exhaust leak. Have mechanic check exhaust manifold gaskets. This will also cause the air filter to be dirty. Clogged air filter means not enough air getting into engine.
I think you are spot on.

Any recommendations for a good diesel mechanic in Venice area?
Old 08-03-2020, 06:47 AM
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Well since both engines not a real failure in one which is a good thing. Look at turbo output and riser area, they do fatigue crack (vibration etc). I had that and it really chokes up the foam turbo input filter.
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Old 08-03-2020, 06:53 AM
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Colemar Services in Covington, LA. Russell Cole is one of the best,
JoeSignorelli
Old 08-03-2020, 07:18 AM
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Ask for maintenance records, if they're available. Try to figure out if a company maintained it or the owner. the company could provide some insight.

Old 08-03-2020, 07:24 AM
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On my 6LYA 1800 RPMs puts you right on the edge of the turbo. Go faster, go slower but don’t stay there.

You might have a leak but remember all mechanical diesels mist a little bit and I bet the ER has never been cleaned.
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Old 08-03-2020, 08:11 AM
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Originally Posted by marlinmike View Post
Well since both engines not a real failure in one which is a good thing. Look at turbo output and riser area, they do fatigue crack (vibration etc). I had that and it really chokes up the foam turbo input filter.
Thanks for the tip, this seems like an easily overlooked area for a leak. Easy to go to manifold and gaskets.
Old 08-03-2020, 08:18 AM
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Originally Posted by BOSBoatMan View Post
On my 6LYA 1800 RPMs puts you right on the edge of the turbo. Go faster, go slower but don’t stay there.

You might have a leak but remember all mechanical diesels mist a little bit and I bet the ER has never been cleaned.
Thank you for the RPM tip.

The rest of the boat appears to have been well maintained, I could see people overlooking ER cleaning.

I have asked about maintenance records and they have not found them. They may have done it themselves as I found handwritten notes in some of the manuals.

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