Replace turbos?

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When I say rebuild, i mean i am getting new ones built.
 
Most times where the water enters the exhaust riser is NOT where its squirted into the exhaust stream.

Internal passages allow the water to cool the riser before discharge.
 
Gordon, it sounds like you are way ahead of us, just post some pictures when you are done (just for me, actually!).

I have a 6CTA but dry stacked but I am very interested in your work.
 
Downside?

djmarchand said:
Gordon:


You restated your problem, ok, so now listen to my restatement of diagnosis you need to make to find the cause:


As Ski noted earlier, most boat systems direct crankcase blowby back to the air intake. Usually it is not very oily, but three things can make it oily: bad rings, an overfilled crankcase and an AirSep system.


You can easily check for bad rings by putting your hand in front of the blowby tube while there is some load on the engine. You will feel heavy exhaust pulses. Or remove the filler cap and feel for pulses.


An overfilled crankcase can let the crankshaft whip the oil up and out the blowby vent. This is probably the most likely cause. Lower the oil level by a quart and see what happens.


Finally an AirSep system can overpressure the crankcase and force oil out with the blowby and then into the intake. They work fine on DD 2 strokes but especially on the Cummins B, they do not. That is why Seaboard Marine (Tony Athens' company) developed their Envirovent system for the Cummins B and C.


AirSeps were factory installed on some Bs and yours may have them. Read the following. It is detailed and tedious but it describes exactly what may be happening to your engines: EnviroVent CCV Kit 4BT & 6BT Series - Seaboard Marine


Check for these three problems before rebuilding your turbos. I'll bet it is one of them.


David
Click to expand...

David,

I have relooked my engine and do not have a CCV system installed. At best, I think the only way for oil to get into the turbo, other than through the oil supply line.

So lets tackle this issue from another angle: if I were to just continue using the turbos, what would happen during failure, other than needing to shut the engine down. On big trucks, a turbo failure can result in down stream damage to the charged air cooler (something analogous to an after cooler on boats).

If I just let it ride so to speak, what is the potential downside, other than having to limp back into port?

Gordon
 
Gordon:


You may not have a CCV system installed, but you do have a crankcase vent which goes somewhere. If it just dumps into the engine room, then any entrained oil mist will be sucked up into the intake. Even more directly if the blowby vent hose terminates at the air inlet like my Yanmar 6LY.


So, you have eliminated one of my proposed causes- a malfunctioning AirSep. So how about eliminating the other two rather than continuing to focus on the oil supply to the turbo bearings. If a turbo seal is bad, I don't see how it is going to get oil on the air filter as you described, except maybe at shutdown and it will only be on the bottom.


So, check for excessive blowby from wherever the crankcase is vented and lower the oil level and see if your problem goes away.


I am no expert on turbo failures, but if it is a lubrication related failure, the bearings will get loose and the turbo blades will start to rub on the housing and the turbo will stop turning. I think that you will get plenty of warning due to not being able to hit the rated rpms of the e


David
 
David,

I don't know if what you wrote was a typo, but I am not getting oil on the air filter, but inside and particularly the housing in front of the intake fan. And naturally, any oil accumulated there would drain to the bottom of the housing.

I will drain a quart of oil from both engines, wipe turbos clean and see what happens. I have seen blowby in the engine room only upon startup, but not after the engines have run for a couple of minutes. I am probably out to lunch, but I don't see how that much oil could accumulate from blowby going into the engine spaces.

I will continue checking and reduce oil.

Thanks
Gordon
 
Gordon:


From your first post " I do have Some oil in the air cleaner."


Also, if you are seeing blowby on startup, that is a problem. Even if it is a fraction after it warms up which I doubt, it won't take much to show up in the air cleaner or the intake turbine. Every bit of that blowby either settles out in the engine compartment or gets sucked up by the engine.


Please check blowby first, before doing anything else. And if it is noticeable, install Seaboard Marine's Envirovent system. The entrained oil will be coalesced and contained in a "puke bottle" and not sucked up into your intake.


David
 
"The entrained oil will be coalesced and contained in a "puke bottle" and not sucked up into your intake."

Why would one care?

Oil all around the ER is a big mess , but a tablespoon in the intake?

Oil burns , all gone!
 
I have no oil all around engine room so am at a loss to explain.
 
djmarchand said:
Gordon:

I am no expert on turbo failures, but if it is a lubrication related failure, the bearings will get loose and the turbo blades will start to rub on the housing and the turbo will stop turning. I think that you will get plenty of warning due to not being able to hit the rated rpms of the e
David
Click to expand...

I'm no expert either, but I did have a turbo on my Dodge/Cummins pickup "fail" from the bearing wearing out and the impeller blades hitting the housing. No way this would have stopped the turbocharger from spinning. It simply ground off the impeller blades and sucked the metal dust into the engine. That did not hurt anything as far as I could tell.
I found the problem because one day after shut down I could hear the blades hitting as the turbo spooled to a stop.
But underway I did not experience any power drop nor could I hear any noise.

In Gordon's case I would simply put a piece of oil diaper to catch the drool and cruise on.
 
So I found the blow by today. On this boat, the blow by Vince to the outside via a 10 foot long 1 inch hose. So, the oil is deafly not coming from the blow by. A mechanic friend of mine looked at it and said clearly the oil is coming from a leaking oil seal on the turbos.

His take was that as long as there is oil the bearings are in no danger and will probably get some more use out of the turbos. I am still thinking about changing them,however, or I should say getting them rebuilt while I have the exhaust system apart.

Gordon
 
If blowby vents outside the boat, and if by chance there is a low spot in the hose, oil will a accumulate there and form a liquid trap. That will pressurize the crankcase and force oil out the turbo shaft seals.
 
Ski in NC said:
If blowby vents outside the boat, and if by chance there is a low spot in the hose, oil will a accumulate there and form a liquid trap. That will pressurize the crankcase and force oil out the turbo shaft seals.
Click to expand...

Well dammit....I learn something new everyday!!!
 
vent tube

Ski in NC said:
Yep, if blowby is vented into turbo as most are, some oil can ooze around compressor scroll and is a non-issue.

On a B-motor, the envirovent system is a big improvement over the factory blowby vent.
Click to expand...

Ski,

So to follow your thinking on the Boat Diesel forum, you think the engine is not venting from the vent tube and gases, laden with oil, are making their way back to the turbos? How are the gasses getting there, to the turbo, that is? Your thinking is that using the envirovent system will solve the problem? Tony seemed to pooh-pooh my answer that gases might be entering from the oil return tube.

I would love to get Tony's take, but am thinking my pictures are not quite up to his standard.

Gordon
 
Gordon J said:
So I found the blow by today. On this boat, the blow by Vince to the outside via a 10 foot long 1 inch hose. So, the oil is deafly not coming from the blow by. A mechanic friend of mine looked at it and said clearly the oil is coming from a leaking oil seal on the turbos.

His take was that as long as there is oil the bearings are in no danger and will probably get some more use out of the turbos. I am still thinking about changing them,however, or I should say getting them rebuilt while I have the exhaust system apart.
Click to expand...


So does that mean simply replacing the seals is a fix?

-Chris
 
Have you checked crank case psi. It's a possibility that your current setup is causing a restriction when you are running hard. Increased crank case psi can cause seals to leak that normally wouldn't.
 
ranger42c,

I am waiting for Tony Athens from Boat Diesel to weigh in. My analysis may be flawed, although it seems to be logical.

Boy, I have got to stop using the ipad and iphone for email and messaging.

I'll let you know what I do.

Gordon
 
If a liquid trap is formed in the long blowby vent line, blowby gasses will have to build some pressure to work past the liquid trap. This will pressurize crankcase slightly and force oil out the compressor shaft seal.

The other possibility is the mist being drawn back into engine room where it is ingested by the turbo compressors, but if that is a 20 foot hose it does not sound likely.
 
crank case vent

With the idea that a lot of methods are interesting, may even be
inspirational, though not directly applicable, here is a picture.

The engine is a Cat 3406. The vent tube is 1 1/2 or 2 inch, it
follows the exhaust pipe (dry) to exit through the stack on the cabin top.

Ted
 

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Ted said:
With the idea that a lot of methods are interesting, may even be
inspirational, though not directly applicable, here is a picture.

The engine is a Cat 3406. The vent tube is 1 1/2 or 2 inch, it
follows the exhaust pipe (dry) to exit through the stack on the cabin top.

Ted
Click to expand...

That is certainly one way to do it!!!! I have engine envy. The Cat 3406 is about as good as it gets when it comes to higher powered marine diesels(I am a big QSM fan as well)!!!
 
Baker,
That engine isn't mine, it's in a boat I looked at, seriously, before
I got Okisollo.
Okisollo has a turbo charged D353 Cat, same hp at a lower rpm.

Ted
 

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Cat 353... Drool. That's a real engine.
 
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Reactions: Ted
Damn turbos! Glad I don't have any.
 
My only experience with turbos is two turbo cars, but I'm tempted to just say, if he has boost pressure, he is not burning excessive oil, and none is spraying round the ER, then he's good to go - it is cosmetic only, and worth trying to prevent via the various suggestions made, but by and large he can and should, be getting out there asap.

Checking to excess crankcase pressure makes sense, and if absent, possibly the oil feed lines to the turbo's bearings are leaking, and a little oil can go a long way when stirred up by heat and movement, making where it comes from not always obvious. (Bitter experience) But it sounds like overkill to just rebuild what might be fine turbos with a simple issue only.
 
I have to say I am so far disappointed in the response to my query from Boat Diesel. Ski seems to have the best idea what is going on. Tony Athens can't seem to follow the thread from one day to the next, or, I am being impatient.

Gordon
 
Gordon J said:
I have to say I am so far disappointed in the response to my query from Boat Diesel. Ski seems to have the best idea what is going on. Tony Athens can't seem to follow the thread from one day to the next, or, I am being impatient.
Click to expand...
Don't bite the hand...
 
Gordon J said:
I am being impatient.

Gordon
Click to expand...

Yes you are. I have been a boatdiesel member for more than 10 years. Tony wants all the fact before he makes a recommendation. He won't do it with only partial sketchy information.
Plus he has a business to run. He openly volunteers expert advice.
You need to respect that.
 
I take back all said. I thought this was part of his business, and did not understand that he was an unpaid volunteer. I do respect that.

Gordon
 
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