2 cracked exhaust elbows - MTU

[markc]

Update...

I soaked the bolts numerous times yesterday in WD40 penetrating release and attemped to remove them this morning. All the bolts required some effort to remove, but mainly due to being awkward.

As you can see from the photo, both elbows suffered the same failure. It appears that they were only leaking via the flange as the gasket split. The elbow is double walled and the internal wall was intact.

Next job, try to get hold of replacrments

 

[vas]

nice and buggered!
good going getting them off without any issues.
Managed to find who builts them and how much for a couple?

finally what's these nipple things with M10 bolts (or thereabouts) on them?
Do you have EGT measurement, if not maybe time to fit some sensors there, no?

cheers

V.

 

[Deleted User YDKXO]

Mapis, this could be successfully welded with no problems, but as it appears to be a casting of a poor quality and a clearly defined stress line, you are right to be concerned as to the durability and reliability of any welded repair as while you can weld any cast material, any poor quality materials or components with an inherent flaw would be so compromised to the point of "why take the risk" in this instance.

I think its a bit unfair to label the casting as poor quality. After all it has successfully resisted vibration and shock loading in a boat that is more than 20yrs old, I believe! Also we dont know if the elbow has been properly supported during its lifetime although knowing Ferretti boats as I do, I suspect it has. Agree you could weld repair the crack but better to replace with new if the part is still available (which might be doubtful)

 

[Portofino]

Common with overtightening, torque spec here is normally 20-25nm or less just clip it in lightly and wind until the leak stops

Nice work Marc
WD 40 just needs time .
Returning to the aetiology,let’s hope it was just simple over tightening .
Here’s a vid on new gaskets .https://m.youtube.com/watch?v=Mjl1RftWPjc
Along with this and some material off e bay + some exhaust gasket paste you should be able to re bed the replacements .
Make sure you clean up the flange on the engine particularly taking care ( vacuum ) to prevent ingestion of $hit into the turbo vanes - not good .

 

[markc]

nice and buggered!
good going getting them off without any issues.
Managed to find who builts them and how much for a couple?

finally what's these nipple things with M10 bolts (or thereabouts) on them?
Do you have EGT measurement, if not maybe time to fit some sensors there, no?

cheers

V.

MapisM has pointed me in the direction of Confe at the OEM suppliers, but they've yet responded to me. I may well have to take one home with me and see if I can get them fabricated.

I don't have egt sensors, however these 'nipples' appear to have perhaps been the culprit in weakening the casting, the ones on the other bank of cylinders on both engines don't have this and are fine. I was wondering if the 'nipples' on the bottom of the elbows were for EGT - maybe I should look at fitting some sensors there? I also have a M10 take off from the exhaust pipe that joins the output from both turbos - not sure if I have to record on each elbow, from each turbo, or just use this single one from each engine... however that's another story!

 

[markc]

Nice work Marc
WD 40 just needs time .
Returning to the aetiology,let’s hope it was just simple over tightening .
Here’s a vid on new gaskets .https://m.youtube.com/watch?v=Mjl1RftWPjc
Along with this and some material off e bay + some exhaust gasket paste you should be able to re bed the replacements .
Make sure you clean up the flange on the engine particularly taking care ( vacuum ) to prevent ingestion of $hit into the turbo vanes - not good .

Thanks L. Gaskets are just a big ring, so should be fairly easy to make if they're an exorbitant price from MTU. I'm also going to replace the gaskets on the 2 good ones too whilst I am at it as I'll re-torque those too.

 

[MapisM]

MapisM has pointed me in the direction of Confe at the OEM suppliers, but they've yet responded to me.

Sorry to hear that they didn't answer your email yet.
I only got in touch once with them, btw when I was considering an F175 which was in need of rebuilding the whole exhaust system, and the engineer I spoke with over the phone was very helpful.
I must still have his mobile number somewhere, so I could ring him and check if they can help with your needs, if you wish.

I was wondering if the 'nipples' on the bottom of the elbows were for EGT - maybe I should look at fitting some sensors there? I also have a M10 take off from the exhaust pipe that joins the output from both turbos - not sure if I have to record on each elbow, from each turbo, or just use this single one from each engine... however that's another story!

At first I also thought that they could be meant for the pyrometer sensors of EGT gauges, but since you told that they are only on one cylinder bank of each engine, that wouldn't make much sense.
In fact, theoretically, the best way to keep EGT monitored should be on each cylinder (very handy in case of one faulty injector), but afaik only much larger engines have that sort of setup.
Otoh, all V engines with EGT monitoring which I came across have at least separate sensors for each cylinder bank.
So, it could well be that you already have a plug specifically meant for the pyrometer on each of your 4 turbos.
As you know, we have the very same MB blocks on our boats, and even if MTU and MAN marinization is different in several ways, I wouldn't be surprised if the turbo (which afaik was built by KKK for MAN, hence possibly also for MTU) would be the same.
Below is a pic of the exhaust connection on one bank of my engine.
As you can see, the exhaust system downstream of the turbo is very different from yours, all built in s/steel and with an extremely short dry section (the pipe visible on the left border of the pic, attached to the main exhaust pipe, is where the raw water goes back into the jacketed section of the exhaust).
And in that very short dry section, there is a small plug which could be used for the installation of a pyrometer sensor, somewhat similarly to your "nipples" - see the red circle on the left.
But actually, I was told by a MAN engineer that also the plug in the section right after the turbine and before the flange (red circle on the right) is designed for the same purpose.
So, it could be that you've got a similar provision also on your turbos, in which case I'd rather replace the elbows with some others with no additional bits welded to them. In fact, I believe it's ordinary business for exhaust system builders like Cofeme to fabricate elbows with exactly the same size and curvature, in the event that the original cast parts aren't available anymore.

 

[markc]

I must still have his mobile number somewhere, so I could ring him and check if they can help with your needs, if you wish.

That would certainly be amazing, if not too much trouble of course!

 

[MapisM]

Roger wilco, no trouble at all.
I'll email you the results - or post them here, if potentially interesting also for others.

 

[BartW]

P, it looks as if the elbow has been taken off; fairly new mounting screws and soot prints on the white parts,
was that during your ownership ? do you know why ?

 

[markc]

With MapisM's help (thanks!) I have had some communication from Cofeme and they have confirmed that the elbow is made by MTU. I will try and get a cost from MTU for a pair, but I suspect the cost will be astronomical, so will likely try and get them fabricated. Wondering if carrying one of the busted elbows will exceed my checked baggage allowance with BA tomorrow!

 

[Assassin]

I think its a bit unfair to label the casting as poor quality. After all it has successfully resisted vibration and shock loading in a boat that is more than 20yrs old, I believe! Also we dont know if the elbow has been properly supported during its lifetime although knowing Ferretti boats as I do, I suspect it has. Agree you could weld repair the crack but better to replace with new if the part is still available (which might be doubtful)

Mike, I said it "appeared to be" and not that it was, we only have photographs of the items and their cracks to work with. Poor quality not only means materials as it includes the initial designs and structural loadings which create stress lines and at around this time there were a lot of failures of these and similar components on many aftermarket/alternative engines fitted into plant and heavy equipment so it wasn't confined solely to marine applications and the cause was generally poor quality materials or poor design and the common denominator was outsourcing to Asian low volume suppliers of such components. Some large names got caught out and even BMW got caught out with poor casting on some of their exhaust manifolds for performance variants of several car models.

 

[Portofino]

Mike, I said it "appeared to be" and not that it was, we only have photographs of the items and their cracks to work with. Poor quality not only means materials as it includes the initial designs and structural loadings which create stress lines and at around this time there were a lot of failures of these and similar components on many aftermarket/alternative engines fitted into plant and heavy equipment so it wasn't confined solely to marine applications and the cause was generally poor quality materials or poor design and the common denominator was outsourcing to Asian low volume suppliers of such components. Some large names got caught out and even BMW got caught out with poor casting on some of their exhaust manifolds for performance variants of several car models.

“ Performance variants “
“Poor quality “
“ poor design “
“ large names “

Yup :encouragement:

https://www.ferrarichat.com/forum/threads/f430-header-failure-it-can-happen-to-you.377467/

https://www.carcomplaints.com/news/2016/ferrari-f430-engine-problems-lawsuit.shtml


The chassis was designed up from a flat planed 3.6 L 5 valve head cam belted engine derived from F1 .Launched in 1999 called a 360 Moderna .
Redline near 9000 rpm .
Problem is the Americans suggested in semi automatic mode it lacked low down torque .Naturally as it was supposed to be revved up ,come alive north of 5000 , really bursts into life from 7500 rpm = magic .They struggled with “ stick shift “ gearboxes from a marketing POV .

Simultaneously the group developed a normal 4.3 V8 for Maserati ,with trad single firing order for smoothness , 4 valve head and chain driven cams - this revved a lot lower produced more power lower down was more tractile for the American auto ( actually semi paddles ) market .Called it a 430 launched 2005 hailed as the successor to the 360 .

Problem is in the 430 it’s the same dimension rear subframes / chassis etc as the 360 .
They fitted a wider 4.3 V8 .Yup the Masser derived V8 is wider physically, than the original screaming F1 derived V8 .
Point is this the exhaust manifolds are on the outside of the V had to turn in a tighter space .
Compounded by cat packaging- = huge failures .
Initially Ferrari just replaced with std replacements - ie the same part not acknowledging an issue .
Then aftermarket manufacturers started to make / design / fabricate etc a better set ,removing the primary cats so,s to get the angke of the bends less acute - remember it’s a tight fit between the suspension turrets .

Sorry about the TD .

How ever re design exhaust manifolds that get extra hot ( not your boggo cars ) don,t like tight bends = excess thermal stresses are amplified.

So back to marine diesels

1-We know about EGTs and overloading = higher temps , but I don,t think Marc thrashes his boat .
2- 90 degree bends , hmm ?? - the hotter they get the more they don,t like acute bends !
3- And over tightening the flange bolts I guess just amplifys the thermal stress.
4- And as said earlier I would ck out that expansion joint spec - if it’s too stiff there nowhere for the stresses to go , or put another way it will amppily stresses in the elbow .

So we are back to “ design “ which I understand both builder and engine supplier collaborate ?

 

[Latestarter1]

Mark,

Sorry to see you have expensive woes, in the windfarm business standing joke is that when you get a bill from MTU it is always More Than U expected!

On a more serious note I would suggest that a fabricated replacement is the only cost effective solution. However me being me I would love to see pictures/drawings of whole layout, looking at the cracking I cannot help suspecting water ingress being part of the failure mechanisim.

If you want to post more detailed installation info will happily give my two pennyworth...

Paul

 

[markc]

Thanks Paul

I don't think water ingress has played a part as it's in the dry section of the exhaust

As you can see from the photo below, both turbos exit via a similar elbow connected to an expansion joint (Porto, these have plenty of flex) to a main exhaust (the black insulated pipework). The water enters the exhaust very close to the underwater exit (see 2nd picture)

I've also included some photos of the elbow. It appears to have a double wall as the internal wall is intact, but the outside is cracked. The internal pipe extends out of the top and sits inside the expansion joint. The exhaust was leaking from the flange crack where the gasket failed too. The elbow is fixed to turbo by 2 clamps with 3 bolts each, to 50nm, so there are no bolt holes in the elbow.

 

[MapisM]

I don't think water ingress has played a part as it's in the dry section of the exhaust

Actually, the (very interesting, as always) comment from LS1 could still make sense, M.
In fact, water ingress isn't necessarily related to the re-injection of raw water into the exhaust pipe - it can also happen with the engines turned off.
Having (carefully!) considered both a Ferretti 175 and 165 during my search, and having spoken with both Ferretti and MTU engineers, I know for sure that the following can and did happen.

In the 175, which was the first Zuccon designed Ferretti, with a very sleek and low profile, its powerplant (V12 MTU 183TE92) only had a few inches of free space between its turbos and the e/r roof.
As a consequence, some of the earliest boats suffered BAD water reversal damages, when moored in marinas where the wash created some roll, slowly but constantly reversing some sea water into the exhaust.
I have it on good authority that some of those pretty expensive engines were completely wrecked (just imagine turning them on after some cylinders were filled with sea water!), and had to be completely replaced under warranty.
Afterwards, some modifications were made to the exhaust system, retrofitting also the already built boats.
That included some large external flaps, easily visible just inside the u/w exit. An item to be carefully checked periodically btw, because if it gets stuck close it can lead to serious backpressure problems, and if it gets stuck open, it fails to do what it should, i.e. protect from water reversal in particular conditions (rolling and/or backward current, for instance when the boat is moored in a channel).

All that said, I never heard that also the 165 (which was designed and built after the 175) suffered the same problems.
Besides, the earliest 165 were powered by the V10 MAN, and only the later ones (like yours) fitted the V8 MTU 183TE93, slightly less powerful (775 vs. 820 hp) but obviously lighter.
So, the 165 e/r is actually large enough to accomodate also the longer V10 block.
Otoh, having seen both models, I can confirm that the space above the engines is very similar (at least visually), if not even tighter in the 165.
Now, pretty sure at Ferretti they weren't happy to replace engines under warranty, so they must have done something right after the earliest experiences with the 175.
But LS comment rang me a bell, and I thought to mention this story even if I can't be positive about any 165 involvement.

Just as an additional thing that you might be interested to know, while I was very much in doubt between a beautifully maintained 175 and the DP I eventually bought, I spoke with the Cofeme engineer that you are now in contact with, because I didn't like the external flap solution potentially prone to get stuck, and he suggested an alternative: a controllable valve, installed between the wet section of the exhaust and the hull, which could be either completely closed (after turning the engines off) or open (before turning them on again), with some alarms to assure a proper operation.
A bit overkill maybe, considering that the boat I was considering was built in the early 90s and still running fine, but if I should have gone for her, I would have given that solution a careful thought, along the lines of better safe than sorry...

 

[Portofino]

Actually, the (very interesting, as always) comment from LS1 could still make sense, M.
In fact, water ingress isn't necessarily related to the re-injection of raw water into the exhaust pipe - it can also happen with the engines turned off.
Having (carefully!) considered both a Ferretti 175 and 165 during my search, and having spoken with both Ferretti and MTU engineers, I know for sure that the following can and did happen.

In the 175, which was the first Zuccon designed Ferretti, with a very sleek and low profile, its powerplant (V12 MTU 183TE92) only had a few inches of free space between its turbos and the e/r roof.
As a consequence, some of the earliest boats suffered BAD water reversal damages, when moored in marinas where the wash created some roll, slowly but constantly reversing some sea water into the exhaust.
I have it on good authority that some of those pretty expensive engines were completely wrecked (just imagine turning them on after some cylinders were filled with sea water!), and had to be completely replaced under warranty.
Afterwards, some modifications were made to the exhaust system, retrofitting also the already built boats.
That included some large external flaps, easily visible just inside the u/w exit. An item to be carefully checked periodically btw, because if it gets stuck close it can lead to serious backpressure problems, and if it gets stuck open, it fails to do what it should, i.e. protect from water reversal in particular conditions (rolling and/or backward current, for instance when the boat is moored in a channel).

All that said, I never heard that also the 165 (which was designed and built after the 175) suffered the same problems.
Besides, the earliest 165 were powered by the V10 MAN, and only the later ones (like yours) fitted the V8 MTU 183TE93, slightly less powerful (775 vs. 820 hp) but obviously lighter.
So, the 165 e/r is actually large enough to accomodate also the longer V10 block.
Otoh, having seen both models, I can confirm that the space above the engines is very similar (at least visually), if not even tighter in the 165.
Now, pretty sure at Ferretti they weren't happy to replace engines under warranty, so they must have done something right after the earliest experiences with the 175.
But LS comment rang me a bell, and I thought to mention this story even if I can't be positive about any 165 involvement.

Just as an additional thing that you might be interested to know, while I was very much in doubt between a beautifully maintained 175 and the DP I eventually bought, I spoke with the Cofeme engineer that you are now in contact with, because I didn't like the external flap solution potentially prone to get stuck, and he suggested an alternative: a controllable valve, installed between the wet section of the exhaust and the hull, which could be either completely closed (after turning the engines off) or open (before turning them on again), with some alarms to assure a proper operation.
A bit overkill maybe, considering that the boat I was considering was built in the early 90s and still running fine, but if I should have gone for her, I would have given that solution a careful thought, along the lines of better safe than sorry...

Bingo - - having seen the ER pics .Answers why it’s the outside pair only .

As said need to know the Aetiology, then you can hopefully mitigate against a repeat .

 

[markc]

Bingo - - having seen the ER pics .Answers why it’s the outside pair only

I'm not sure I agree. Only the outside elbows have been modified post casting with a welded in 'take off' .. both sides failed along the weld, and only on the outside wall of the elbow, not internal. Considering the age of the elbows, the heat cycles and the weakness caused by the welds, this seems far more likely.

 

[Portofino]

I'm not sure I agree. Only the outside elbows have been modified post casting with a welded in 'take off' .. both sides failed along the weld, and only on the outside wall of the elbow, not internal. Considering the age of the elbows, the heat cycles and the weakness caused by the welds, this seems far more likely.

Arh - “outside “ so unlikely to be what MapishM is advocating.
Agree with your analysis thus far .

Always diff making long range diagnoses without an examination

 

[vas]

seems to me you all have points, maybe a combo of heating cycles and a bit of seasoning with back splash of seawater...

Marc, what's the distance (as in HEIGHT ABOVE!) from WL at rest and the point that the flex thing joins the big black dry exhaust bit?
It seems to me to be something like 20cm
and furthermore, mixing point must be even less.

Not sure LS would be happy with such a setup (considering his suggestions on a rusted turbo I had- ended up building new SS elbows going all the way up to 3cm from the salon floor to get enough head and keep water out)

V.