Beneteau ST 44 potential sea water intrusion

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DavidM

DavidM

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Tom (sunchaser), I and others are helping Richard (don't know if he is a TF member) over on Boatdiesel figure out why both turbos on his twin Volvo D4 powered Beneteau ST 44 recently failed. The pics he just posted on boatdiesel definitely show corrosion in the turbos due to sea water intrusion, probably from the exhaust system.

I would encourage all TF members with this boat and engines to review this problem on boatdiesel at http://boatdiesel.com/Forums/index.cfm?CFAPP=6&Forum_ID=619&Thread_ID=63733 to see if their boat may have the same problem.

I suspect that it ruined Richard's first pair of engines (Volvo replaced them) and it has now ruined the turbos on his new engines and will eventually probably ruin the new engines if not corrected.

He posted pictures of the exhaust system on boatdiesel. It has a flat run from the mixer back to the lift muffler which may let water slosh back up from the muffler.

We don't as yet know about the geometry dimensions but Richard will post them to boatdiesel once he gets his new turbos installed. Look at the attached pic to see the best geometry for this type of installation. Not all boats can achieve this and there are some things you can do if you don't have the room to do it this way.

We can continue the conversation with TF members who have concerns about this problem on this thread. We might want to start a parallel thread on boatdiesel, but for now let's stick to this one.

David
 

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I keep hearing about this sort of thing, and it astonishes me that boat builders continue to design exhaust systems this way, and that engine manufacturers accept the installations. I guess it's a calculated risk, betting that most boats are moored in calm conditions where they won't get bitten by this, and/or it will last long enough to be out of warranty....

I think I saw just this in a picture on TF recently (can't remember if it was a Swift Trawler or other boat). The exhaust from the engine sloped down to the mufflers, where a better design would have been for it to run up as high as possible in the ER, then loop down.
 
Is this a danger scenario particular to Beneteaus? If not, there are a lot of unsafe boats out there, if I’m reading the diagram correctly.

On our Defever, the exhaust mixer spillover is at or just below the waterline and the “hump” in the exhaust hose is at least a foot higher than the mixer. Yet I haven’t heard about an epidemic of engine back-flooding. What am I missing?
 
djmarchand said:
Tom (sunchaser), I and others are helping Richard (don't know if he is a TF member) over on Boatdiesel figure out why both turbos on his twin Volvo D4 powered Beneteau ST 44 recently failed.
Click to expand...

Believe that would be Rclarke246.
 
angus99 said:
Is this a danger scenario particular to Beneteaus? If not, there are a lot of unsafe boats out there, if I’m reading the diagram correctly.

On our Defever, the exhaust mixer spillover is at or just below the waterline and the “hump” in the exhaust hose is at least a foot higher than the mixer. Yet I haven’t heard about an epidemic of engine back-flooding. What am I missing?
Click to expand...

What you describe in your Defever is very typical of sailboat exhaust systems. They are not inherently safe according to the diagram. The engine sits low and the lift muffler is also low. But there is a very high exhaust loop after the lift muffler. That loop is high enough to prevent waves from pushing sea water up and over the loop.

But if the loop is not high enough and I suspect that is the case on Richard's ST44, sea water will go over the loop, ultimately fill the lift muffler and back flood the turbo.

There are ways to mitigate this, but lets let others chime in first before discussing them.

And if you follow boatdiesel for long, you will hear of many situations of sea water intrusion corroding turbos. I'll bet that at any one time there are 1 or 2 active threads on this topic at boatdiesel and at least a dozen new ones each year. So boat and engine manufacturers aren't doing much to avoid bad exhaust installations.

There are also many, many boat owners who replace their turbo thinking it is a consumable item. In almost all of these cases it is due to sea water intrusion and they have no clue what is happening. Turbos rarely die a natural death.

David
 
I put some thoughts on the BD thread.
 
I'd suggest any owners also contact Beneteau and get what they have to say on this issue. I'd want some official statement from them regarding my own boat.
 
Yes, someone please share contact name/email/phone. would be best they address this before failure. I specifically avoided buying a particular boat a few years ago because it had a major exhaust/cooling design flaw that everyone was struggling with. IIRC both the engine manufacturer and boat builder partnered together to try to fix.
 
I would prefer that this thread focus on fixes rather than point fingers at Beneteau or Volvo.

David
 
djmarchand said:
I would prefer that this thread focus on fixes rather than point fingers at Beneteau or Volvo.

David
Click to expand...

as a part of that would be good to understand each of their stances and what their recommendations (if any) are to prevent from happening on all the ST44 they have produced to-date. they likely (hopefully) have someone with advanced skills on their teams that can help address.

also, i dont think that rclarke's prior engine replacement had to do with sea water intrusion. the engines were eating oil. further, it should be noted that he probably has one of the first ST44 (if my memory serves me, he has a 2012 and that was the first year of the ST44) and therefore may be experiencing failures and such ahead of everyone else.

would be interested to know if anyone else has opened their turbos and also if Beneteau has introduced any design changes in the exhaust configuration since 2012.
 
Hope this isn’t too much drift, but on the subject of flooded engines, I found a side view of an older Defever 44 . . . maybe an ‘82, when they still had masts and FL 120s powering them. But the basics are pretty similar to later models. The engine exhaust is about 6” above the design WL and, moving forward, the exhaust hose slopes upward about 2 feet before plunging down to the muffler. The exhaust mixer is, as I suspected, at the water line.

Granted, few if any Defevers of this vintage had turbos. But if this is an inherently unsafe design, I’d be interested in knowing why flooded engines aren’t a topic I’ve ever seen discussed on the Defever forum.
 

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angus99 said:
The engine exhaust is about 6” above the design WL and, moving forward, the exhaust hose slopes upward about 2 feet before plunging down to the muffler. The exhaust mixer is, as I suspected, at the water line. .
Click to expand...

That design as you describe sounds similar to my vessel. I'd guess that DeFevers made in the past 25 years are all with turbos. The drawing does seem clear enough to see similarities between old and new.. Three things on my vessel:

  1. The downward slope from the ER area to the sea is "extreme" thus preventing waves or water coming into vessel when engines off. This good angle is allowed by the high salon floor above the engines. As well, retained water in hose flows to stern except for smaller amount that may flow back downhill to muffler.
  2. On mine the water lift muffler is sized to accept about 3X the volume of drain water in the hoses when engines are shutdown. My water lift is well less than half full at shutdown, I know because I've pulled hose off to peer into muffler.
  3. I have working vent loops on the raw water line going to the elbow thus stopping any tendency for siphoning/backfilling through engine or stern tube following shutdown.
I'd guess there are good reasons you don't read about engine back flooding on the DF forum. they are rare or non existent. DeFever picked up his wet exhaust designs from the crew and officer boats he designed for use in the Pacific during WWII. Big waves and issues when you're dropping a Captain's wet exhaust gig from the deck of a battleship into the rolly seas below.

Then he began designing offshore tuna charter boats for SoCal and Mexican waters, never calm there and engines are frequently off. Surprisingly the incidence of the engine back flooding for the thousands of Taiwanese and Chinese built trawlers don't seem too common if at all. DeFever design pirates at work?

Certainly Ed Monk knew how to do it as well. His exhaust designs litter the landscape in past, present and future wet exhaust vessels across many brands.
 
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Let me restate this again. The diagram I attached is the ideal. All water even if it completely floods the lift muffler will run back out over the exhaust loop to the transom before it backs up into the turbo because the spill over point just before the mixer is higher than the exhaust loop.

The Defever with its 2' high loop is enough to pretty well insure that no wave will back up into the lift muffler. But if it possibly did it could back up to the turbo if the muffler filled over time.

So the Defever design is good, and it works, but due to its geometry it isn't inherently safe like the picture.

BTW, that picture comes from Tony Athens, the Cummins/Yanmar guru formerly of boatdiesel who has his own website now at sbmar.com/community.

David
 
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Is there any relationship between the sea water affected turbos and the observed water leak where the exhaust line meets the transom?
 
Sent an email to my list of Beneteau contacts to see if they have an "official" position on the exhaust/turbo issue.

Stay tuned.......
 
Thanks for the background, Tom and Dave. Just one more reason I’m glad I don’t have turbos.
 
djmarchand said:
I would prefer that this thread focus on fixes rather than point fingers at Beneteau or Volvo.

David
Click to expand...

I would prefer the problem didn't exist. However, I think in working on a fix, Beneteau should be involved. They should have the most knowledge of the issue. I don't see speaking to Beneteau as pointing fingers at all. You're asking for their observations, advice, assistance. Everything I've seen so far about Beneteau and Volvo's responsiveness to problems has been positive. They've shown willingness in many cases to go above and beyond. They need to be involved.
 
Can't comment specifically on the Beneteau exhaust issue (although I did own two of their sailboats in a past life:socool:). Thought I'd throw out some observations over the years of doing my own boat maintenance and helping dock neighbors with their power systems....

I've worked on a couple engines that had rust/carbon buildup in the turbo body that had blocked the exhaust blades from turning....resulting in black smoke under load and reduced top end power. Fortunately, they were resurrected by removing the exhaust elbow, scraping/vacuuming the loose buildup from the turbo body, spraying a LITTLE bit of PB Blaster in the blade area, and rotating the turbo shaft with a socket and ratchet until no contact with the turbo body. I attributed the rust to what I call "backspatter and misting" (Texas term:lol:) from the water lift muffler, as these owners were known to idle their engines too much in my humble opinion. My thought is that low speed operation doesn't do a good job of blowing the water out of the muffler, and you get a warm salty mist/splatter back up the exhaust tube to the turbo. This is why, after cooldown, I always rev up my engines to clear the excess water from the mufflers before shutting down my engines.

Just my observations...YMMV, and you can stick it in your hat to chew on later, or chunk it on the fire with the rest of the cow chips! :popcorn:
 
greysailor said:
My thought is that low speed operation doesn't do a good job of blowing the water out of the muffler, and you get a warm salty mist/splatter back up the exhaust tube to the turbo.
Click to expand...

Good point. One can always pull a hose of the muffler and see how full of water it is after a "normal" shutdown. Whether Beneteau or other vessels.
 
Sorry that I’m late to reply to this thread.

FYI, Yes, Volvo did replace both of my engines, at 400 hours, for excessive oil consumption. The new engines came complete with new turbos. Both of These new turbos seized up, at exactly the same time, with only 60 hours on them, an impossible coincidence. I’m pretty sure that my conclusion below is accurate.

Here is what I just posted over on boatdiesel:

“My original engines and turbos had no such problems in the 400 hours of use before they were replaced. This was previous case which you can review on this blog and TF. Also, No other ST 44’s have reported anything like this and I do keep in touch with many of them.

The Volvo mechanics and I believe that the following factors caused the problem:

1) Starting The engines monthly without going to full operating temperature, for 5 months. SW Florida has hot and humid summers, a contributing factor.

2) Not putting turbos under any load during these same 5 months.

3) Stern into Hurricane Irma’s 125 MPH easterly wind and rain as she made landfall on Marco Island, FL., September 10, 2017.”

Lessons learned!

The full turbo replacement and labor cost about $8,500, but there is about $1,200 coming back to me for the salvage value of the old turbos. Volvo looked deeply into this case and offered me $3,000 as a gesture of goodwill, which I accepted.

BTW, again, I found Volvo very forthright and easy to deal with on both cases. I have been told, and believe, that they will work with their users with good cooperation so long as the user is honest and reasonable. In my 2 cases, and in most dealings all of my life, I have managed to avoid lawyers & lawsuits.

Working out well, so far!
 

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rclarke246 said:
Sorry that I’m late to reply to this thread.

FYI, Yes, Volvo did replace both of my engines, at 400 hours, for excessive oil consumption. The new engines came complete with new turbos. Both of These new turbos seized up, at exactly the same time, with only 60 hours on them, an impossible coincidence. I’m pretty sure that my conclusion below is accurate.

Here is what I just posted over on boatdiesel:

“My original engines and turbos had no such problems in the 400 hours of use before they were replaced. This was previous case which you can review on this blog and TF. Also, No other ST 44’s have reported anything like this and I do keep in touch with many of them.

The Volvo mechanics and I believe that the following factors caused the problem:

1) Starting The engines monthly without going to full operating temperature, for 5 months. SW Florida has hot and humid summers, a contributing factor.

2) Not putting turbos under any load during these same 5 months.

3) Stern into Hurricane Irma’s 125 MPH easterly wind and rain as she made landfall on Marco Island, FL., September 10, 2017.”

Lessons learned!

The full turbo replacement and labor cost about $8,500, but there is about $1,200 coming back to me for the salvage value of the old turbos. Volvo looked deeply into this case and offered me $3,000 as a gesture of goodwill, which I accepted.

BTW, again, I found Volvo very forthright and easy to deal with on both cases. I have been told, and believe, that they will work with their users with good cooperation so long as the user is honest and reasonable. In my 2 cases, and in most dealings all of my life, I have managed to avoid lawyers & lawsuits.

Working out well, so far!
Click to expand...

For some reason I thought Volvo was replacing the turbos at their cost since they were still under warranty? Stinks that you are out about $5,500 not too mention the down time and head ache. Playing devils advocate, is there anything in the operators manual about your points 1 & 2? Regarding point 3, were there any facts showing this definitely contributed?

Finally, regarding staying in touch with other ST44 owners, I am going to guess that many haven't had their turbos opened up yet for maintenance. I'd be curious to hear from those that have, what they looked like..
 
I'm still due the $1,200 salvage value from the cores.

Volvo policy is that even parts replaced under warranty, in my case the new "bobtail" engines, do not come with a new warranty. They only carry the original warranty period, if any remains. I know, sounds crappy but that's their policy.

The Operators Manual is vague and thus somewhat in my favor as it doesn't state that engines should be brought up to temp and put under load. I used this in my appeal. I accepted their offer and wrote off the $4,200 to lessons learned. Be sure to blow out your turbos on every run, if you can.

No, there are no facts that the hurricane was a contributing factor but it certainly didn't help.

BTW, my turbo pressure readings are both around 65 at WOT.
 
rclarke246 said:
I'm still due the $1,200 salvage value from the cores.

Volvo policy is that even parts replaced under warranty, in my case the new "bobtail" engines, do not come with a new warranty. They only carry the original warranty period, if any remains. I know, sounds crappy but that's their policy.

The Operators Manual is vague and thus somewhat in my favor as it doesn't state that engines should be brought up to temp and put under load. I used this in my appeal. I accepted their offer and wrote off the $4,200 to lessons learned. Be sure to blow out your turbos on every run, if you can.

No, there are no facts that the hurricane was a contributing factor but it certainly didn't help.

BTW, my turbo pressure readings are both around 65 at WOT.
Click to expand...

65 each or total?
 
“Volvo policy is that even parts replaced under warranty, in my case the new "bobtail" engines, do not come with a new warranty. They only carry the original warranty period, if any remains.”

FYI.....This is normal with most if not all mfg’s
 
Your pictures clearly show salt water corrosion on the turbo throats. I think that issues 1 and 2 had nothing to do with your turbo problems. Issue 3, Irma was the cause. Had you started the engines immediately after Irma it would probably have blown the water out and you would be fine today.

I still believe that your exhaust system is marginal and another Irma situation will trash your turbos and if left long enough will trash your engines. You now have two cases of water intrusion and I would fix the exhaust system before you have three.

David
 
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