Yamaha T9.9EXHZ
Outboard Fresh Water Flush System
Revised: Oct 05
This web page
is authored and maintained by Dana Arenius
This web page has no affilation
with Yamaha-Motors, Inc. or other manufacturers of equipment shown within
this page and is for private use only. Engine modifications like
those depicted are alternative choices and judgements of the engine owners
and may not be authorized by the manufacturer. The author of this
web page will not accept liability for engine damage or loss of warranty,
etc. resulting from information posted on this web page. The
modifications shown are those of the author for his personal equipment
only and provided to the viewer as point of interests only.
Comments and questions are welcome
by E-Mail.....darenius@verizon.net.....Please enjoy the Page!!!!
PHOTO TAKEN SHOWING 2001 Yamaha T9.9EXH
Engine with Added Fresh Water Flush
This
photograph shows a custom fresh water system which has been added to a
2001 Yamaha high torque 9.9HP outboard. The flush system features
front water hose connection and provides a water flush supply to three
general areas...the power head, internal right hand side upper exhaust
casing, and internal left hand side upper exhaust casing. The engine
does not need to be running for the flush operation. Such engine
modifications must be weighed carefully by the owner as to any warranty
implications which might be in force on the engine. One does see
aftermarket kits for outboard and I/O units but generally for 30HP or more.
Background
The 2001 Yamaha 9.9 and
4 HP four stroke engines for this model year are not provided with fresh
water flushing. For those of us who sail salt water, flushing is
one of the most important steps for maintaining our engines after each
sail. Many flushing systems are designed just for the power head.
But over time, the exhaust casing can develop serious corrosion resulting
in extensive repair costs. Besides flushing the power head, this
system also injects fresh water throughout the upper casing using three
injectors on each side. The injectors are designed to spray upward
to cover the underside of the exhaust guide plate, the oil pan sides (four
stroke engines has these) and the sides of the upper casing. This
results in a "wash down" of the internal casing. Many of these
upper casing areas can not be normally reached even if the engine were
run in fresh water or flushed with "ear muffs" after saltwater use.
This is because the normal cooling water for this model only passes through
the power head and the rear section of the upper casing where the power
head cooling water discharge is used to cool the idle gas exhaust.
As for the powerhead flush, it was only a matter of picking a cooling water
jacket location on the engine which was connected to the water pump discharge.
Some of the Major
Components
The major components of
the flush system are the distribution manifold, water supply pipe, and
the water injectors. Having owned a previous version of this model
for the past 17 seasons, I was familiar with the internal cooling system
and the locations of the oil pan, drive shaft, etc. I also used my older
engine as a model for the work. I choose the right hand side of the
engine compartment as the entry point of the water supply piping and distribution
manifold. The water supply entry point into the engine compartment
was through the remote control access rubber bushing.
Picture of the manifold......Manifold
is directly connected to 5/8" ID automotive type heater hose from the flush
water supply...made from a piece of 1/2" type L copper pipe with soldered
end cap, it has three 1/4" barbed hose connections which supply flush water
to the power head, left side upper casing injectors, and the right side
upper casing injectors. The OD of the 1/2 copper pipe is, of course,
5/8". A piece of hose cutoff on the right side provides a cushion
within the engine compartment. The 1/4" barb clamps are two ear SS
clamps. The 5/8" hose clamps are all 3/4" ID all SS screw clamps...
Picture of the Supply
Piping....(shown outside the engine for clarity)...The gooseneck
piping assembly was made from 45 and 90 degree copper plumbing fittings
with short sections of soldered straight sections of type L copper plumbing
pipe for the 5/8" ID hoses to the 3/4" to 5/8" barb brass female garden
hose connector on the right and for the 5/8" hose connection which goes
to the distribution manfold to the left. A short piece of the engine
remote gear shift rod had to be removed to fit the 90 degree pipe fittings.
A brass male garden hose plug is used to close the supply when the flush
is not in use. For the Yamaha 9.9, the distribution manifold is located
to the left of the carburetor and the supply pipe assembly is located to
the right. The interconnecting 5/8" ID hose is run under the carburetor.
Manifold and Supply
Pipe Together.......With the 5.8" hose connecting the two, the
manifold is shown located under the yellow oil level stick to the left
of the carburetor and the supply pipe assembly on the right side.
A loom clamp secures the supply hose pipe to the outside surface of the
engine cowling. One can see the three injectors of the right side
upper casing flush supply branch. I took advantage of existing 1/2"
diameter wide by approximately .32 inch thick upper casing "bumper" pads
to install water injectors. This allowed for 8-9 full thread engagements
for my 1/4-28 threaded injectors. These conveniently located thick
pad locations existed for all six injector locations except for the center
right hand side injector location. The normal thickness there allowed
for only 4 thread engagements so I built up the thickness to the thickness
of the others with JB Weld and SS washers. Three injectors are required
here because upper casing oil pan supports divide off the space between
the injectors. The injectors were my own design but have an approximate
.11 inch diameter supply bore in each. The injectors direct
spray upwards, spraying under the exhaust guide plate (the plate the power
head is mounted to and which seals the top of the upper exhaust casing)
and washing down the sides of the casing, oil pan, etc. The injectors
are connected together with 1/4" hose and barbed tee connectors.
Left Side of Engine....showing
the left side upper casing injectors and the power head flush water injector
mounted on the exhaust cover plate (between the two spark plug wires on
the left side of the picture. This injector location for the power
head flush is the only one required to provide the power head with flush
water. I installed a check valve in the 1/4 inch line which feeds
this injector to avoid cooling water bypass during normal engine operation.
Its location on the cover plate is critical because of cooling water
passages which are located on the internal perimeter of the cover and because
of internal cross brace stiffeners. I removed the cover to install
the injector. There are two sandwiched covers here separated by two
gaskets. New gaskets are required to reinstall the covers.
The inner cover separates cooling water from the engine exhaust port cavity.
The space between the outter cover and inner cover is cooling water which
has just come from the water pump. From here part of cooling water
is channeled horizontally along each cylinder exhaust before it exits
and is dumped into the upper casing for cooling the idle exhaust.
One can see the discharge hose connections under each of the spark plugs
for the cylinder exhaust port cooling. The rest of the cooling water
goes up the engine, around the cylinders and through the thermosat located
in the middle of the timing belt. The thermosat sealing edge is fluted
so some water always gets by it. A thermosat discharge hose connects
to the exhaust port discharge tubes before it all goes into the upper casing
(not shown).
To make it all work, I just hook up the
water connection and open the a hose valve at its end. I can adjust
that valve to control excessive supply pressures by monitoring the amount
of indicator water flow....
Hope
you enjoyed the page!
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