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| Tony's Tips |
ARTICLE DATE: 10/01/2006 |
| Marine Exhaust Systems |
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| Marine exhaust system design
failures |
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1) New 44 FT power Cat from
Australia with new 6LYA Yanmars. |
| The boat was sold here locally and
on the first trip out to the islands in "prevailing weather," while fishing
with the engine off and the boat bobbing up and down, both engines had the
aft cylinders fill with salt water. Luckily the captain called me and I
told him what he had to do to salvage the engines. That night after a long
tow back to the dock, we pulled the injectors and flushed the cylinders
out. The next month was spent re-doing the exhaust system ( about a $12K
job). |
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| When the captain
looked in the engine room, he saw water dripping out of the turbo
- Think he was in trouble? This was the vessels maiden "fishing"
voyage. |
Custom Replacement
Riser with temporary exhaust wrap - "Use all available height". |
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2) New 26 FT vessel with a Yanmar 6LPA and
a Bravo #3 drive. |
| The stock riser was about 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. |
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| This shows the WL
inside the factory riser. - Over the top or "spill over" point - What
are they thinking ! |
"Toasted" Yanmar
6LPA 315 at 150 Hours - The builder did not believe in gravity or
Cardinal Rule #1 |
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3) 3126 CAT Factory Wet Risers & result |
| These pictures show what is "typical"
marine type couch engineering mixed with FACTORY salt water cooled wet risers
that were installed on a 3126 CAT. The factory risers were made of Stainless
Steel with the salt water inlet at the bottom of the riser. Two 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" (have seen this on new Mainships
too), water would drip down the riser during cranking and after shut down
damaging the turbo. After about 3 1/2 years/200 hours in service, the riser
failed internally leading to total failure of the turbo and failure of the
#6 cylinder exhaust valve. CAT later changed from Stainless Steel to Bronze
construction for this design (that solved the "rotting out internally part"
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 understand the issue (gravity being the main culprit) and they
finally dumped the entire design with the last generation of 3126 CAT's
and the newer C-7's. |
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4) Factory wet elbow made from junk materials |
| If you recognize this design of a wet
elbow on your boats exhaust system, I'd be checking the internal condition
of it often after the first 3 or 4 years of "marine age", regardless
of total engine hours.... |
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5) Results of a very poor design
from a "builder" that wanted "NO INPUT" during the construction. |
| Original builders design and installation: Results
of very poor design and "Mickey Mouse" exhaust wraps. On the maiden voyage
and seatrial, engine room ceiling tile caught on fire. |
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| 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. Guess who's wallet picked up
the $6500 "redo" tab? Just like most of the time, the owner !! |
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6) Volvo Factory supplied wet 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
complaining about black smoke. We pulled the air cleaner and found the turbo
was binding.. Noticed external water leaks on the factory supplied exhaust
mixer and pulled it. The inside was also leaking and some rust was apparent
on the exhaust turbine wheel w/ lots of crusty carbon/salt build up.. Cleaned
it all up and installed a new "factory elbow" at the tune of $2800 each
- he did not want a custom unit. The overall design, multiple pieces, and
internal seams and welds says it all. Very poor design and he is sure to
see the same failure again as the new elbow was of the same construction.
In my opinion, the owner got off easy as it could have been a lot worse. |
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7) 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 buyer 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 water input elbow go against any common sense as to
water flow restriction, with the overall design with internal welds in the
jacketed area, this elbow will fail and leak into the turbo when it does
rot out internally (just a few years down the road at best). The supplier
(a well respected popular engine distributor) should not be in this part
of the business, or at least use a different company to design and build
the exhaust mixers and risers. The first pair of supplied units were recalled
for possible cracked welds. Just another sad example of "couch engineering". |
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| This picture shows
the initial design of the "factory". Within 50 hours cracks developed
on the outside alerting the owner of a problem. Of course, it would never
crack on the inside!! |
After this showed up,
the "factory" distributor decided they needed to do something. They sent
new mixers with a "Band-Aid" fix - Time will show that this is not a
fix for an inherently very poor design. |
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| "Fixed" replacement
mixer. Add some gussets, a "Mickey Mouse" water inlet, polish it a touch
and viola, the owner thinks he's OK... Remember, he didn't pay much for
the fix, and he received the same - NOT MUCH !! |
Another view of the POS design of a "wet mixer". Why even waste the time & materials building such a piece. That's what I'm trying to figure out!! |
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8) Complex SS wet riser that the owner thought was "cool", but after 1 year of frustration and over $10,000 in repairs, he finally saw the light. |
| 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 - One time the burst
hose took out a new Inverter. Then, after dealing with that issue (working
with another local mechanic that had no clue) the unit failed internally
and took out the turbo. About $10,000 later we finally got it fixed right.
Moral of the story: Never never do you want a raw water jacketed riser !!! |
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9) This design went 3 months before the engine hydrauliced for the last time. |
| This builder thought for sure you could put the riser/turbo at the waterline, inject water in a jacketed riser that is close to level, and then push it up hill - Within 3 months and less than 25 hours the engine had water in the turbo and cylinders - Actually it probably had water in it the first day, but somehow the engine did survive for a couple of months... What was he thinking !!! |
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10) "Doomed" |
| This is another example of a repower
job that cost a extra few bucks after someone thought they had it right.
The "repower guy" seemed to think that exhaust systems could be plumbled
like water pipe in a house and attempted to use the factory "one size fits
all" cookie cutter wet elbow. He also forgot about gravity and within 2
weeks had starting problems. The turbo was getting washed daily with salt
water... Designing a proper riser the first time around is always cheaper. |
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11) Poorly designed wet mixers |
| These pictures depict what we see quite often with the CATAPILLAR factory wet elbows - Poorly designed wet mixers that "clog" unnecessarily due to a "couch engineered" design...With all the issues we have seen with the different type of CAT Factory wet risers and mixers, I really wonder where they hire their engineers from. |
| We are here to help, so if you need
anything, just drop us a note or post on the forums. |
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