How To Repair Water Leak In Boat Exhaust Manifold
Designing a marine exhaust organisation for a gunkhole is something that apparently takes the back seat during the planning stages when doing a repower. In new boat construction, the design of many systems seems to heart around the "cookie cutter" philosophy, equally builders always seem to desire to or work around a factory designed moisture elbow system that is supposed to "fit all". Besides that, many new builders are more concerned about getting the engine beneath a low deck than worrying about the exhaust and exhaust outlet of the engine being close, at, or Beneath the water line.
As well, and some other all besides common error in frazzle design, is the use of an anti-siphon valve as a "set up-all" for an otherwise poor and sure to fail blueprint. It'southward not that an anti-siphon valve is not needed in many applications, merely "Average Joe" has no clue as to what they tin can do and more important, what they CANNOT do, and how minor changes in the basic pattern of an anti-siphon valve can greatly enhance its effectiveness. More on "Anti-Siphon" valves and their shortcomings below.
The about BASIC of all supposedly understood simply not followed diagrams of a marine frazzle layout is below. Why is it we continually see the LWL of a vessel within just a few inches of the exhaust spill-over betoken? Discover the give-and-take MINIMUM??
Remember this as the "SPILL-OVER" point
The diagram in a higher place seems to elude new boat designers and "repower experts" in so many designs that take toll vessel owners millions of dollars over the years in ruined engines. Simply unbelievable to me that something every bit elementary equally building an exhaust with a minimum of 12″ of safety margin peak is non followed.
Moving on to the full design of the system is where most of the emphasis needs to be when repowering or building a boat. With "design" we mean the entire system from the engine exit point (the turbo outlet in most cases) all the mode to where the exhaust leaves the boat. This includes the "size(southward)" (merely figured that ane out), from the engine to the final exit, type of muffler, if whatever, type of material for both the dry and wet side of the system, and the general routing and actual installation of the system. Information technology seems that many installers and builders plan this very important role of the vessel as an "reconsideration" considering many peachy engine rooms are built with no room remaining to build a safe and well planned frazzle organisation.
Fabric choices when edifice frazzle systems tin vary, but 25+ years of experience and 100'southward of exhaust systems nether our belt in loftier hour commercial applications have shown us that 304L or 316L is good for all of the dry sections and shows no deviation in lasting ability regardless of what "street talk" says. Using 316L for all wet sections is always best. Apply 316L rod for all welding (304 or 316) and if the design uses whatever balmy steel for the dry department, then employ 309L for the mixed joints / weld expanse. TIG is the method of choice for all welding. For all custom FRP exhaust work, the of employ resins that are Class one fire retardant isophthalic polyester resins are our choice and like shooting fish in a barrel to source. Common industry names are Reichhold (DION) and McNichols and are used extensively thru the FRP structural pultrusion procedure and filament winding manufacturing industry. Yous may likewise find many of the more common iso-tooling resins meet these specs and are too an excellent option to employ, although some practice non accept the Form ane rating. IMO, 99% of the time, Class i resins are not needed unless the spec calls for it.
Resin rich lay-ups are best with plenty of thickness ( ¼" to ½") in all joints building upward with glass-strand mat with a layer or 2 stitched textile in-between. We finish with iso-gel coat and surfacing agent when applicable / paint as to what looks right for the job – in all cases our work is e'er vastly more stout than "factory supplied" FRP parts, and we e'er put a two″ – four″ long tube doubler inside all tubes where the hose clamps become. This eliminates the tube crushing that factory pipes/ muffler spigots seem to be very susceptible to.
With sizing and bones construction covered, let's get into exhaust design, as this is the nearly abused and least understood phase of the overall system. "Gravity," I'll say it again, "G-R-A-Five-I-T-Y," is the most important aspect of the design that needs to be addressed and how you lot can employ that force to assistance you pattern a safety and effective exhaust system. Side by side is agreement and knowing where your waterline is in both static and all running weather.
With those ideas fresh in your listen these are some pointers and concepts that you need to consider in the initial planning stages of the blueprint layout:
i) Empathize the difference between a "requirement" and a "recommendation"
From the engine manufacturer regarding frazzle design. They may "require" a minimum specified exhaust pinnacle for safety, simply "recommend" a detail size for the organization based on by experience. Many times smaller frazzle sizes can be used to everyone's advantage and employing an experienced company w/ hands-on experience for this role of the vessel construction or repower is time and $$ well spent.
2) Always employ gravity to your advantage
Water flows downhill then, if y'all have a arrangement that holds water (water jacketed risers for instance) and this system fails internally (information technology'due south not IF it is going to fail, it's WHEN it volition neglect), where will the water go?? Into the turbo/exhaust manifold/cylinders?? Think about YOUR riser or elbow should it fail internally where you can non see it and what might happen. Remember, WET risers are an absolute no-no for any long term application unless they are "coolant cooled." Internal failure of "wet elbows" and custom water jacketed risers is an erstwhile and ongoing problem, regardless of fabric selection and/or other claimed construction features. (See Tip #vii).
three) Always use all of the available height in the engine room
For the riser (where needed and is applied) BEFORE turning over the top and injecting water; i.e. always inject the h2o on the downhill side, or downwards stream of the height of the riser. A wet exhaust organisation with a steep downwardly slope is always better and safer. The inexpensive way out, by using a factory supplied "cookie cutter" designed wet elbow, is not e'er a good or rubber option. When thinking marine frazzle, remember "i size" DOES NOT FIT ALL.
4) Exist sure that IF the choice presents itself in the design of a moisture exhaust system, allow for all of the water to bleed itself from the frazzle when not running
Although this can't always be washed, you tin still build a prophylactic system by utilizing other unproblematic design ideas, custom mufflers, surge tubes, etc. An of import point to remember, IF your muffler, etc., holds water in the static position, then the arrangement is also holding h2o when lifting/pulling the boat at the g. ALWAYS lift the bow first (noticeably bow high) and agree it at that place for a minute or so to let the water drain from the organization. I have seen quite a few destroyed engines that had water slosh upwardly into the cylinders from this exact scenario of h2o rolling back and forth or lifting the stern first when pulling a boat – Unremarkably this is not discovered until launch time and by then the engine is toast.
v) When using a "lift muffler" design, call up that in most cases you tin brand the system "inherently rubber"
By being sure that the engine "spill-over" height is higher than the elevator muffler spill over point. When the water injection is below the h2o line, y'all tin likewise design an "active" anti-siphon valve that is much safer than the typical "auto-type valve" shown or used in most applications (IMO, they are a poor design and should be avoided unless fully understood equally to their shortcomings and checked for proper functioning on a continuous basis ).
Some of the fallacies that still persist today are shown in the "copied" lift-muffler design beneath that is shown in current high dollar color catalogs touting their frazzle muffler products. Thinking that this is an applicative base of operations blazon design for a lift muffler organisation is 100% hogwash and in many cases leads to ruining a perfectly skilful engine because of water rising within the system before the engine starts and afterwards information technology is shut down. What they should exist maxim is to blueprint a riser BEFORE the water injection to use all of the superlative available within the engine room, and to design an anti-siphon organisation that allows an active and "open" siphon break to exist on the upward rise of the water injection system allowing h2o to flow over the side Earlier the water flows into the lift muffler filling the system.
Once again, some other instance of 100% "couch engineering" from an engineer that has probably never done and/or seen an install of a marine engine at or beneath the waterline and just gives or sells his "expertise" based on theoretical circumstances on newspaper calculations. This kind of literature angers me equally I know it's total garbage. However, I exercise admit that when this type of engineering is taken for "gospel," I brand lots of $$ considering information technology assures me of continuous new engines sales down the road.
The general layout of the "anti-siphon" valve. In reality, information technology's non a valve at all, simply an active bypass that should be installed on the uphill water flow before it goes over the top, and discharged over the side to a higher place the waterline in a VISIBLE location. This allows cranking without flooding the elevator muffler and adds an enormous layer of safe to the system.
6) Overall Exhaust design can usually exist made better in many ways if you Exercise Not employ "cookie cutter" type exhaust components
Typically, many use factory 90 caste wet elbows, and an array of 45 and ninety degree bend hoses and clamps routing an frazzle. I guess most installers think of a marine exhaust system like copper plumbing in a firm.
A simple change from a 90 degree angle bend to a 75 degree curve, an angled input to a muffler, or an added twist in a riser tin make a world of difference in overall exhaust layout. In other words, don't just think "direct, 45 & ninety" when designing an exhaust system. In the 100's of exhaust systems nosotros have designed over the last 25+ years, I am sure that at to the lowest degree 50% of them had to have something custom done to a "factory muffler" in order to make the exhaust layout "fit" blueprint criteria.
An Interesting Notation: I have tested the pressure driblet of a typical 75 degree custom elbow from both 6″ to 8″ and 5″ to 6″. In both cases, at 430 HP on the 5-6″ elbow, and at 660Hp on a 6″ to 8″ elbow, I never saw more than ¼" Hg delta. Going from smaller to larger allows a quick expansion and lowers pressure restriction overall even in relatively sharp moisture bends. Less bend would even be better.
7) Never, never, never do yous want a boat that has saltwater cooled wet risers or pipes unless they are installed in such a manner that when they leak they are downhill of the engine "spill-over" point
Information technology is not IF they are going to leak, it's when they are going to leak as it is a 100% given that they will. If this is the just viable selection, and so exist sure that y'all realize that they need to be inspected annually (or more often), or changed out later every few years to be safety. A few examples below of perfectly good low hr engines that had a "wet riser" or something similar and when they failed internally, the possessor was into the BIG bucks as to repair.
8) When the vessel design is such you lot are very limited as to the physical dimensions of the exhaust size
(like installing a muffler in a confined space) and y'all need to reduce back pressure only you cannot install larger pipes, tubes, etc, some other option would be to bypass some of the water that is normally mixed into the wet exhaust.
In most cases, the engine seawater system pumps more than enough water to cool the engine and sometimes as much as 2+ times water than needed to cool the exhaust.
This can vary as to engine design AND exhaust pattern, but bypassing approx 1/3 of the water that leaves the heat-exchanger or cooling system on the engine and sending information technology over the side of the boat tin easily reduce dorsum pressure by 1″ Hg or more in some cases.
An added do good of this is that it can add a "visual" as to water period and, in many boats, this would exist a plus as the seawater water flow is sometimes impossible to determine.
Knowing that you are pumping seawater e'er adds comfort to your experience. If this is something that you lot feel would be needed, employ the services of a visitor that has a rail record in this type of work as information technology would be time and effort well spent.
9) Reference sketches and ideas:
Marine exhaust system design failures
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1) New 44 FT power True cat from Commonwealth of australia with new 6LYA Yanmars
The gunkhole was sold hither locally and on the first trip out to the islands in "prevailing weather," while fishing with the engine off and the gunkhole bobbing upwardly and down, both engines had the aft cylinders fill up with salt water. Luckily the helm called me and I told him what he had to do to salvage the engines. That dark after a long tow back to the dock, nosotros pulled the injectors and flushed the cylinders out. The next month was spent re-doing the exhaust system (about a $12K job).
2) New 26 FT vessel with a Yanmar 6LPA and a Bravo #3 drive.
The stock riser was virtually 2″ above flooding when brand new and within the first year, as the vessel got loaded with "gingerbread," the engine flooded at the dock. The engine was toast and the owner had to buy a complete NEW engine.
iii) 3126 True cat Factory Wet Risers & event
These pictures show what is "typical" marine type couch engineering mixed with FACTORY table salt water cooled moisture risers that were installed on a 3126 True cat. The factory risers were made of Stainless Steel with the table salt water inlet at the bottom of the riser. Ii things happened over 4 years and 190 hours. Because the riser outlet at the top were designed and installed at such a "shallow down angle" (take seen this on new Mainships also), water would drip down the riser during cranking and after close downwards damaging the turbo. Afterward well-nigh 3 1/2 years/200 hours in service, the riser failed internally leading to total failure of the turbo and failure of the #six cylinder frazzle valve. CAT later changed from Stainless Steel to Bronze construction for this design (that solved the "rotting out internally role" of this poor design) only to have the shallow angle of the outlet come back and bite them on many Mainship installs. It took CAT engineers about 7-8 years to sympathize the upshot (gravity being the main culprit) and they finally dumped the entire design with the last generation of 3126 CAT's and the newer C-seven'due south.
4) Factory wet elbow made from junk materials
If you recognize this design of a wet elbow on your boats frazzle organization, I'd be checking the internal condition of it often afterward the outset 3 or 4 years of "marine age", regardless of total engine hours….
5) Results of a very poor pattern from a "architect" that wanted "NO INPUT" during the structure
Original builders pattern and installation: Results of very poor design and "Mickey Mouse" exhaust wraps. On the maiden voyage and seatrial, engine room ceiling tile caught on burn down.
Our Solution: A re-designed riser and mixer, proper clearances and supports, and 1st Class Exhaust Insulation on the dry sections. In the big scheme of things, this could have been an expensive learning curve. Judge who's wallet picked up the $6500 "redo" tab? Merely like most of the time, the owner !!
six) Volvo Factory supplied moisture mixer for a newer Volvo TAMD 120
This is a Volvo Factory supplied wet mixer for a newer Volvo TAMD 120. At 800 hours and 4 years the owner was lament virtually black smoke. We pulled the air cleaner and found the turbo was bounden.. Noticed external h2o leaks on the factory supplied exhaust mixer and pulled it. The within was also leaking and some rust was credible on the exhaust turbine bicycle w/ lots of crusty carbon/salt build up.. Cleaned information technology all up and installed a new "factory elbow" at the melody of $2800 each – he did not desire a custom unit. The overall design, multiple pieces, and internal seams and welds says it all. Very poor pattern and he is sure to see the same failure again as the new elbow was of the same structure. In my opinion, the possessor got off easy as it could have been a lot worse.
vii) Lack of thought as to both raw water flow, dry riser design
These picture's are a perfect example of a design that may impress a heir-apparent but shows a total lack of thought as to both raw water flow, dry riser design, and long term reliability and safety for the engine because of the "jacketed design" and orientation. Not only does the raw h2o input elbow go against whatsoever common sense as to water period restriction, with the overall design with internal welds in the jacketed area, this elbow volition fail and leak into the turbo when it does rot out internally (but a few years down the route at best). The supplier (a well respected popular engine benefactor) should not be in this part of the business concern, or at least utilize a unlike visitor to design and build the exhaust mixers and risers. The first pair of supplied units were recalled for possible cracked welds. Simply another sorry example of "burrow engineering".
8) Complex SS wet riser that the owner thought was "absurd", but afterward 1 year of frustration and over $10,000 in repairs, he finally saw the lite.
The designer/fabricator tried his best to make a buck – This riser was on a Detroit 650 HP 8V-92 and failed in two ways – The exhaust sprayer (inside pic) was clogging and the engine would either overheat or the raw water hose would burst – 1 fourth dimension the burst hose took out a new Inverter. So, after dealing with that issue (working with another local mechanic that had no inkling) the unit failed internally and took out the turbo. About $x,000 later we finally got it fixed right. Moral of the story: Never never do y'all want a raw water jacketed riser!!!
nine) This design went 3 months before the engine hydraulic-ed for the last time
This builder thought for certain you could put the riser/turbo at the waterline, inject h2o in a jacketed riser that is shut to level, and then push information technology up loma – Inside 3 months and less than 25 hours the engine had water in the turbo and cylinders – Really it probably had water in information technology the get-go twenty-four hours, merely somehow the engine did survive for a couple of months… What was he thinking!!!
ten) "Doomed"
This is another instance of a repower job that toll a actress few bucks after someone idea they had information technology right. The "repower guy" seemed to call back that exhaust systems could be plumbled like water pipe in a house and attempted to use the factory "one size fits all" cookie cutter moisture elbow. He also forgot about gravity and within two weeks had starting problems. The turbo was getting washed daily with salt water… Designing a proper riser the first time effectually is always cheaper.
11) Poorly designed wet mixers
These pictures depict what we see quite oftentimes with the CATAPILLAR factory wet elbows – Poorly designed moisture mixers that "clog" unnecessarily due to a "couch engineered" design…With all the issues nosotros have seen with the different type of CAT Factory wet risers and mixers, I really wonder where they hire their engineers from.
Nosotros are here to assistance, so if you demand anything, just driblet us a note or post on the forums.
Source: https://www.sbmar.com/articles/designing-a-marine-exhaust-system/
Posted by: johnsonhouncest.blogspot.com
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