Wet exhaust elbow explosion?

MagicalArmchair

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Hello friends,

I replaced my stock d2 55 exhaust elbow with the stainless steel version from the fine folk at parts4engines during my heat exchanger rebuild adventure (Heat exchanger repair).

I'm going to do a proper write up of this to help others, and doing my reading around the subject I found the below:

FYB Marine. Volvo Penta genuine exhaust elbows and exhaust gaskets

This includes the alarming statement:

"Never fit a stainless copy exhaust elbow onto any Volvo diesel. We have seen too many exhausts, fracture or explode."

I posed this to Parts4engines technical desk (who I have huge respect for), their response was.

"We have never heard our exhaust outlet to fracture or explode as we have been selling the outlet for years. We sell the replacement outlet in SS for most of our engines.

I can assure this issue we wouldn’t occur and we strongly disagree with the statement from FYB marine"

I can find no evidence of what FYB marine suggest. Has anyone else experianced Stainless steel exhaust elbows fracturing or exploding??

I have reached out to FYB for comment also.
 

Sandy

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I am sure @vyv_cox, as a metallurgist, will be along to comment on technical matters, but I would also be interested in their response. Sounds like arse covering to me.

I have a surprise in store for them! My exhaust elbow is original and fitted in 1986, but I only average 100 engine hours per year.
 

lustyd

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I can find no evidence of what FYB marine suggest
Entirely possible they're talking about when people discard the included gasket and fit the stainless direct to the engine block as per the original, causing issues internally on the block.
 

vyv_cox

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I cannot imagine any mechanism for an explosion due to mixing metals in an exhaust system. Yanmar supply their engines with a stainless exhaust elbow and many people have substituted copy versions in stainless for a wide variety of engines.

So far as fracture is concerned, fabricated stainless steel elbows fail by fatigue, including Yanmar's own. The cause is differing thicknesses of metal, generating stress on heating and cooling.
 

jwilson

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They have probably seen many exhaust elbows fracture, incuding plenty of original Volvo/Yanmar etc ones. But explode????
 

MagicalArmchair

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So far as fracture is concerned, fabricated stainless steel elbows fail by fatigue, including Yanmar's own. The cause is differing thicknesses of metal, generating stress on heating and cooling.
Thank you all, thanks Vyv. That is interesting. I wonder if this is what FYB are referring to?

Volvo Penta D2-55A and D2-55B Stainless Steel exhaust outlet and connector

So the above casting would potentially, after a period of time, suffer the same kind of fatigue? How common is this and after what period of time could you expect failure?
 

Tranona

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They are a Volvo agent and only sell genuine parts, and have probably found their sales have declined as stainless cast (not fabricated) replacement become more widely available from China.
 

Tranona

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Thank you all, thanks Vyv. That is interesting. I wonder if this is what FYB are referring to?

Volvo Penta D2-55A and D2-55B Stainless Steel exhaust outlet and connector

So the above casting would potentially, after a period of time, suffer the same kind of fatigue? How common is this and after what period of time could you expect failure?
The Volvo elbows are castings. Many others, like my Beta 30 are fabrication Beta 3030 hp @ 3,600 rpm - Marine Propulsion Engines Beta Marine where the exhaust tube is welded to the plate and the injection spigot welded to the tube. Both these welds are potential points of failure. Some Yanmars like the 1GM have concentric inner and outer tubes both welded to a plate that mounts on the exhaust manifold. Again points of failure.

Even then "explosions" is over dramatic. You can see pinholes from corrosion in the welds or fractures/cracking but difficult to see how there are any forces involved that could possibly lead to an explosion.

Will be interesting to see FYB response if any.
 

rogerthebodger

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"Never fit a stainless copy exhaust elbow onto any Volvo diesel. We have seen too many exhausts, fracture or explode."

To me this is just an attempt to justify the high price of an OEM part without real evidence

Its the same as using the word marine in any part description
 

nevis768

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I recently purchased a high rise exhaust elbow from FYB marine for my Mascot 28, (2030 B) I had a few questions and I was put through to an engineer who was very helpful. The elbow was expensive, but the service was excellent.
I couldn't find an alternative cheaper version in stainless for this type of elbow.
 

Tranona

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I recently purchased a high rise exhaust elbow from FYB marine for my Mascot 28, (2030 B) I had a few questions and I was put through to an engineer who was very helpful. The elbow was expensive, but the service was excellent.
I couldn't find an alternative cheaper version in stainless for this type of elbow.
The high rise elbow is rare compared with the standard one plus it would be more difficult to cast so not surprising that there is no alternative to the factory one. It is however possible to fabricate one out of stainless tube but as a one off it would probably be expensive. I have a custom made high rise for my Beta and it was a lot of work to make.
 
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