Exhaust elbow

[gonesailing13]

Is there any reason to change the exhaust elbow on the engine other than leaking water ? Mine is old with a little bit of rust but no signs of any leaking water. The boat is 25 yrs old and I’m guessing is the original elbow. Are there any signs I should look for ?

 

[Lepke]

The big problem is plugging with rust. Either where the water comes into the elbow or in some engines, the rust can partially plug the exhaust path. It's probably ok for now, but if you're worried, take it off, inspect, and there are solutions that will dissolve the rust without hurting the base metal. Also, there are marine exhaust companies that depending on engine, make a replacement.

 

[rgano]

What Lepke said. 25 years is too old. Plan on replacing once the inspection is done.

 

[Comodave]

If it is indeed 25 years old then you are living on borrowed time. I would just replace it and move on.

 

[firehoser75]

It does not matter how good a quality a exhaust elbow is, it has a limited life expectancy and will require replacement. Saltwater (or any water) in a high heat environment will cause corrosion. On my first boat, the elbow was cast iron and lasted about 5-6 years before corrosion became a big problem. My last boat had stainless steel and the elbow lasted about 14 years before it corroded through (inside, nothing was visible from the exterior)!!!

Depending on the engine, exhaust design, installation, etc. when an elbow corrodes through on the inside (like mine did), this interior leakage can result in several problems. The biggest problem (and mine had this potential but I caught the issue before any damage was done) is where this interior leakage can migrate back into the turbo (if the engine has one) or into the exhaust manifold of the engine itself. This design "flaw" is referred to as "doomed to fail" by Tony Athens, a marine engine guru on his website sbmar.com. Another problem with elbows that are corroded is they might not deliver a proper cooling spray pattern to the exhaust gases thereby overheating the exhaust hose causing delamination (interior usually so not visible) that can lead to flow blockage and engine overheat, or hose failure and the leakage of large amounts of hot gases and hot saltwater into the bilge.

None of this is good, and some of it can end up very, very expensive. Exhaust elbows are a replacement (maintenance item), and no matter how you look at it, 25 years is way, way past due (in almost all cases). You may want to read up on the "doomed to fail" idea so that you don't just continue on the same path, unless you are lucky enough that your exhaust system was designed and installed properly. I changed mine out to a custom exhaust for about the same price as it would have cost to just replace the stock Cummins elbow, and now, gravity is my friend.

Don't ignore this, as the outcome may not be pretty if you do.

 

[koliver]

This design "flaw" is referred to as "doomed to fail" by Tony Athens, a marine engine guru on his website sbmar.com.

You may want to read up on the "doomed to fail" idea so that you don't just continue on the same path, unless you are lucky enough that your exhaust system was designed and installed properly. I changed mine out to a custom exhaust for about the same price as it would have cost to just replace the stock Cummins elbow, and now, gravity is my friend.

It isn't just Cummins that can be Doomed.

In my first sailboat the Yanmar OEM elbow didn't last 5 years. Luckily the failure allowed hot cooling water to flow into the bilge, not the engine, and only the elbow needed replacement, but that was just luck.

On my Volvos, inspection every once in a while got me through to about 35 years before one showed some pinholes. They were on the insides, around where the designed spray enters the exhaust stream, so the rust and holes were not visible on the outside.
Both sides got the treat of new elbows then, and the new ones are all stainless.
Unlike what Tony Athens describes in great detail on Cummins engines, the pinholes only affected the spray pattern, doing no other harm.

 

[C lectric]

It's not only Tony Athens warning about this.

Some of these things last a long time, some will only last a few years.

They are not forever. As said if yours are 25 yrs old you would do well to replace them.
WHEN they leak they can back feed the engine with seawater doing serious damage.

I know people who, with gas engines, used to replace them every 5 - 6 yrs after they had their warning.

The elbows do not always give warning such as an outside pinhole leak, the pinhole could go inside and feed the engine.

 

[firehoser75]

Keith,
"Unlike what Tony Athens describes in great detail on Cummins engines, the pinholes only affected the spray pattern, doing no other harm."
I have to disagree, at least in theory about the "no other harm" aspect. While it is possible that for a period of time, that a small leak in a well designed exhaust system will not cause much additional damage, if left, or it goes unnoticed for a period of time, additional damage can and will eventually result. For example, in my actual case, the internal leakage resulted in the exhaust hose overheating in "spots" approaching the hose's rated temperature. Way too hot, and if I had not had an exhaust hose overheat alarm, there was no way to know this was happening as I had good water flow, and all engine temperatures were normal. This could have resulted in hose damage leading to delamination, or even hose failure if left long enough. If the hose badly delaminated, it could have resulted in reduced water flow leading to engine overheating, possibly resulting in engine damage. So, What I am saying is, even a small pinhole leak should not be ignored, and you are actually on "borrowed time", at least potentially.

It is true that this is not confined to Cummins engines!!!

 

[koliver]

Keith,
"Unlike what Tony Athens describes in great detail on Cummins engines, the pinholes only affected the spray pattern, doing no other harm."
I have to disagree, at least in theory about the "no other harm" aspect. While it is possible that for a period of time, that a small leak in a well designed exhaust system will not cause much additional damage, if left, or it goes unnoticed for a period of time, additional damage can and will eventually result. For example, in my actual case, the internal leakage resulted in the exhaust hose overheating in "spots" approaching the hose's rated temperature. Way too hot, and if I had not had an exhaust hose overheat alarm, there was no way to know this was happening as I had good water flow, and all engine temperatures were normal. This could have resulted in hose damage leading to delamination, or even hose failure if left long enough. If the hose badly delaminated, it could have resulted in reduced water flow leading to engine overheating, possibly resulting in engine damage. So, What I am saying is, even a small pinhole leak should not be ignored, and you are actually on "borrowed time", at least potentially.

It is true that this is not confined to Cummins engines!!!

Yes, of course there are so many different ways that equipment can fail, it is impossible to generalize. Vigilance is required.

 

[fgarriso]

It does not matter how good a quality a exhaust elbow is, it has a limited life expectancy and will require replacement. Saltwater (or any water) in a high heat environment will cause corrosion. On my first boat, the elbow was cast iron and lasted about 5-6 years before corrosion became a big problem. My last boat had stainless steel and the elbow lasted about 14 years before it corroded through (inside, nothing was visible from the exterior)!!!

Depending on the engine, exhaust design, installation, etc. when an elbow corrodes through on the inside (like mine did), this interior leakage can result in several problems. The biggest problem (and mine had this potential but I caught the issue before any damage was done) is where this interior leakage can migrate back into the turbo (if the engine has one) or into the exhaust manifold of the engine itself. This design "flaw" is referred to as "doomed to fail" by Tony Athens, a marine engine guru on his website sbmar.com. Another problem with elbows that are corroded is they might not deliver a proper cooling spray pattern to the exhaust gases thereby overheating the exhaust hose causing delamination (interior usually so not visible) that can lead to flow blockage and engine overheat, or hose failure and the leakage of large amounts of hot gases and hot saltwater into the bilge.

None of this is good, and some of it can end up very, very expensive. Exhaust elbows are a replacement (maintenance item), and no matter how you look at it, 25 years is way, way past due (in almost all cases). You may want to read up on the "doomed to fail" idea so that you don't just continue on the same path, unless you are lucky enough that your exhaust system was designed and installed properly. I changed mine out to a custom exhaust for about the same price as it would have cost to just replace the stock Cummins elbow, and now, gravity is my friend.

Don't ignore this, as the outcome may not be pretty if you do.

 

[Short Story Long]

I have Volvo TAMD 72 A boat new to me both elbows were shot.
Volvo OMC were 1600.00 bucks ea.
Went with Aftermarket stainless steel from HDI Marine
Half the price of Volvo and better Quality
Good source for elbows not affiliated

 

[warfdog]

Don't wait! Replace the elbow now and every 3-5 years.

A very deteriorated elbow can look perfectly fine on the outside. Don't ask me how I know... This is my new to me TT with the Lehman 120.

The first picture is the old vs. new elbow. The second picture is the rust scale that I knocked out of the elbow. I am estimating that this elbow was more than 10 years old.

There was so much rust scale in the elbow that almost a quarter of the weight of the elbow was gone. The buildup in the elbow (shown in the bag) was forcing water back into the #6 exhaust port which could have been castastrophic had I not caught it just in time. I don't have a good picture of the plugged up condition but it was significant.

All I had to do to repair the damage $$$$ was install a new elbow, rebuild the head and re-machine the manifold. This could easily have destroyed the engine...as it was it only cost me a couple boat bucks.

 

[C lectric]

I did a poor job of my explanation.

Some people get lucky and get just a warning.

Some really lucky people get serious engine damage from failing elbows.

Warfdog's experience is a good example of what can happen. At least his engine did not suffer piston/cylinder damage which can happen in addition.

As said you have a warning. It's good you asked but your luck could run out.

 

[silverback]

Yanmar recommend replacing elbow at 500 hours for my yanmar 6lpa-stp. Mine is 10 years and only 850 hours and is right adjacent to the turbo. So i did. About AU $2000 cost! Yikes! But discovered damage to exhaust hose where it left the support of the elbow. Not visible from the outside, so a bit of a benefit there. And that invaluable feeling of not wondering when i should renew. It looked fine by the way.

 

[Tiffany]

Is there any reason to change the exhaust elbow on the engine other than leaking water ? Mine is old with a little bit of rust but no signs of any leaking water. The boat is 25 yrs old and I’m guessing is the original elbow. Are there any signs I should look for ?

The problems - as others point out - are most likely developing on the inside. Exhaust hose internal delamination due to an unequal spray pattern from a partially blocked elbow is one. A 25 year old elbow is past its service life and you are gambling a very expensive engine and repair bill against a modest and essential maintenance item. It's not a bet I would keep putting my marker down on.


I would plan on replacement and go for stainless steel; the added cost comes back in extended service life and confidence.



Cheers, Doug

 

[koliver]

Is there any reason to change the exhaust elbow on the engine other than leaking water ? Mine is old with a little bit of rust but no signs of any leaking water. The boat is 25 yrs old and I’m guessing is the original elbow. Are there any signs I should look for ?

I have recently replaced my exhaust elbows.
I had an issue that saw me in the shop. While there, I had the elbows inspected. One had a rusty area on the inside, where the spray exited the elbow. The other was still good. Both were 35 yrs old, both had in excess of 6000 hours on them. Both were replaced.
Many engines lose their exhaust elbows earlier than this. Some may go much longer. Mine may have gone much longer. Or not.
If you are worried about yours, at the very least, take them off and get them inspected by someone who knows what to look for.

 

[BruceK]

Recent SS replacements with ceramic coating for my Cummins 210s were $2.5K AUD each. A shiny work of art to tart up any ER, and obviously a lot of work goes into making a double walled complex ss tube.
The Lehman replacements years ago were by comparison simplicity in design and commensurately cheaper. From memory my insurer required they be checked every 5 years, suggesting past experience with failing elbows.

 

[warfdog]

Recent SS replacements with ceramic coating for my Cummins 210s were $2.5K AUD each. A shiny work of art to tart up any ER, and obviously a lot of work goes into making a double walled complex ss tube.
The Lehman replacements years ago were by comparison simplicity in design and commensurately cheaper. From memory my insurer required they be checked every 5 years, suggesting past experience with failing elbows.

A lehman exhaust elbow is less than $200 US with a gasket and new pipe fitting. It should be thought of as a low-cost maintenance item, an insurance policy against much more expensive damage, and if you remove yours then there is no reason even to put the old one back on at that price. Just replace it.

 

[SoWhat]

I replaced the exhaust hoses on my Lehman twin 90's. Decided to replace the exhaust elbows just to be thorough. They were 35 years old. I could have reused them and gone another 35 years. Or maybe 35 days. I sleep well while anchored.