# Clogged Exhaust or Mixing Elbow: Clean or Replace?



## oft (Apr 25, 2006)

The topic of soot build-up in the exhaust elbow and/or mixing elbow has been mentioned several times, but I wondered what the general wisdom was about cleaning vs. replacement. Can these items be cleaned when they get clogged or should they just be replaced? If they can be cleaned, are there any tricks? Thanks for any advice.


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## TSOJOURNER (Dec 16, 1999)

Well if its in good enough shape, why not clean it out. If its rusted or in too bad of shape, remove and replace. As far as cleaning, im not sure how to go about that. I figure just remove it and clean it out with a stiff wire brush. That would be my go at it.


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## speciald (Mar 27, 2007)

I hacd my elbow cleaned last Winter. It was removed and then "pickled" like they do for a heat exchanger. When it is off the boat they can tell whether it needs replacement or only cleaning.


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## JohnRPollard (Mar 26, 2007)

oft said:


> The topic of soot build-up in the exhaust elbow and/or mixing elbow has been mentioned several times, but I wondered what the general wisdom was about cleaning vs. replacement. Can these items be cleaned when they get clogged or should they just be replaced? If they can be cleaned, are there any tricks? Thanks for any advice.


I was told by a trusted mechanic that they can be easily cleaned. I don't have my notes with me, but he suggested removing then soaking the elbow overnight in a commonly available acid who's name escapes me, but which is available at most hardware stores (muriatic acid, perhaps, possibly oxalic acid?). Hopefully somebody here will know which. I wouldn't recommend guessing!


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## SteveInMD (May 11, 2007)

I was told you can clean it, but don't expect to double the life span after cleaning it. Often the metal corrodes from the inside out and they eventually crack. Remember, you are dealing with carbon monoxide here.


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## camaraderie (May 22, 2002)

If the metal is good, a 5% muriatic acid bath will clean it up nicely. Available cheap in the Home Depot...generally near the concrete supplies.


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## Omatako (Sep 14, 2003)

Most automotive engineering shops will have a tub to hot-soak the part in and get rid of all the internal scale for a few bucks.

Talk your locals, they're sure to be able to help.

Andre


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## badsanta (Oct 16, 2006)

The one on the yanmars are a wear item, so they are ment to be replaced every few years


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## Maine Sail (Jan 6, 2003)

*My vote...*

My vote is..... REPLACE IT..! If it's old enough to be clogged it's old enough to be replaced.

Many times the damage can't physically be seen until you smash one with a hammer to see the effects of the sulfur in the fuel. This one has be smashed open and you can literally see the corrosion and crumbling metal through the entire thickness of the elbow. This elbow still had clean gray paint on it right next to areas of crumbling metal!!

The elbow its self is SHORT money considering the consequences of a failure at an inopportune moment..


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## JohnRPollard (Mar 26, 2007)

halekai36 said:


> The elbow its self is SHORT money considering the consequences of a failure at an inopportune moment..


Yeah, ours is 18 years old (original), and if I went to the trouble of removing it I'd go ahead and replace with new.


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## Pamlicotraveler (Aug 13, 2006)

We replaced ours this year for the very same concerns mentioned. The consequence of misjudging the strength could be a failure that would then flood the engine with Salt water at an inopportune point.

From Yanmar


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## beej67 (Apr 2, 2008)

Yanmar says replace every 8 years.

Ours started to clog right at the 8 year mark, like clockwork. Replaced it as per the recommendation. It really wasn't that expensive. I think the part is less than a hundred bucks.


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## FarCry (Apr 21, 2007)

Started replacing mine on Wednesday...finally got the broken bolt out of the exhaust manifold last night. My engine is a Yanmar 2QM so not only do I get to replace the elbow but also a flange that the elbow threads onto and then bolts to the manifold. Having enjoyed spending 12 hours trying to become a pretzel to access bolts, I also am replacing all hoses and clamps that are in the vicinity of the back of the motor and hope to not find myself down there again for a looooong time.

Note to self and others...when the wife mentions a new exhaust smell in the head and companionway...listen and investigate. My exhaust elbow had a crack that was more than six inches long. Fortunately it was in a place that was letting dangerous lethal gases enter into the interior and not gallons of seawater. And we thought the headaches were from too much rum the night before, possibly not. Once the elbow was removed, it is amazing to me that the engine was able to run at all, nearly completely clogged.


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## sailingdog (Mar 19, 2006)

FarCry—

I'm surprised you don't have a CO detector aboard your boat. If you had, you would have had warning long before it got to the headaches stage. You were risking CO poisoning... which is often FATAL. You should probably add a CO detector ASAP.


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## FarCry (Apr 21, 2007)

SD--The list of things that are "not" on the boat is much longer than the list of things that should be on the boat. I was being sarcastic about the headaches. On the rare occaision that we motor for a few minutes to anchor, moor or pull into our slip, the the companion way is open and well ventilated. Obviously that is not a solution to the problem. Your CO2 suggestion is appreciated and I will add it to my list of things to do. However my spouse seems to be an effective detector. By replacing the exhaust elbow, hoses and clamps hopefully I will be temporarily lower my risk of inhaling toxic fumes.


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## SteveInMD (May 11, 2007)

I've found CO detectors to be unreliable on boats. They seem to false alarm frequently due to humidity, or if you use any spray cleaners near them, or in certain phases of the moon <joking>. Is there a reliable sensor out there?


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## sailingdog (Mar 19, 2006)

The domestic ones certainly are, since they're not designed for a a high humidity environment. The marine-specific ones, like the Fireboy Xintex seem to do fairly well.










SteveInMD said:


> I've found CO detectors to be unreliable on boats. They seem to false alarm frequently due to humidity, or if you use any spray cleaners near them, or in certain phases of the moon <joking>. Is there a reliable sensor out there?


</joking>


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## FarCry (Apr 21, 2007)

SD, I went to the Xintex website (How do you know all this stuff?) and looked at the Fireboy products which do seem like the appropriate sensor for the task. From their website I copied this:

Ideal for boats requiring additional CO alarm protection and for boats without a CO alarm. 
The CMD-1MR-9V uses an advanced biomimetic sensor to determine CO levels. Time Weighted Average sensor technology is used to eliminate false alarms. 

Install one unit in every sleeping area, galley, and confined space for adequate protection. Extremely low battery consumption – only .016 mA. 

Ceiling or wall mount
Dimensions: 4.75” diameter x 1.5” depth
9V battery included
1-year limited warranty
UL 2034 Listed for Marine use.


CMD-1MR-9V
9V battery powered
Carbon Monoxide Detector

By their description I would need 4 units, galley, V-berth, head and engine compartment area to fully cover my 31' vessel. That would be about $600 worth of sensors. When compare to a life, that is a bargain but is still a substantial investment when compared to other safety equipment that is needed. Your suggestion is appreciated but my priorities move this quite a ways down on the list.


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## sailingdog (Mar 19, 2006)

Farcry-

I do a lot of research. You might want to get a single unit for the main cabin to start with. That would only be about $100 or so...and would provide some level of protection for you and your family... while still being fairly low-cost. The one in the photo is a stand-alone unit and is only $99. It is the one I have installed on my boat.


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