My second hand boat comes with a 1995 Mercury 115-hp 2-stroke outboard
motor. Unfortunately, the boat doesn't come with an owner manual and I
don't know when the manufacturer will mail the owner manual to me. I
need some info about maintaining this motor:

- It is a 2-stroke motor with oil-injection (this means oil is not
mixed with fuel in the tank). I cannot find anything that looks like
an oil filter. Is this normal?

- Do I expect to see a fuel filter somewhere to trap water in the
fuel? Is it a good idea to retrofit a fuel filter to the fuel line if
the fuel system doesn't come with a fuel filter?

- I am trying to locate the screw hole for draining engine oil from
the lower part of the outboard motor. I can see two screws in the
right side of the lower part of the outboard. They are a couple inches
apart, and one is above the other by an inch. Which one is the one
that I should unscrew in order to drain oil from the lower part of the
motor? Where is the vent hole for draining oil?

Thanks in advance for any info.

Jay Chan

On the bottom of the lower unit near the skag you will find an oil plug,
this is to fill/drain the unit. The two plugs you mentioned up higher: The
lower one is to vent the lower unit while filling/draining, the other is to
drain water from the water pump housing.

You might want to consider mixing gas and oil at a ratio of one bottle of
Merk oil to 5 gallons of gas. The bottle will tell you to mix one bottle
with 6 gallons of gas. I always mix it heavy on oil, spark plugs are a lot
easier to change than pistons and crankshafts. I have never had any
problems with this heavier mix, Merk oil burns clean and leaves only a
slight residue in the cylinders, usually it can be wiped out with a cloth
during a tear down after 30 years of hard use!

Meks oil injection has not been the most successful thing they ever did and
a lot of motors have burned up because of it. By using gas/oil mix you
eliminate that risk totally.

The carbs have a screen filter in the cap where the fuel lines attach. An
external water separating fuel filter between the tank and the motor is a
good idea.

Don Dando


wrote in message
oups.com...
My second hand boat comes with a 1995 Mercury 115-hp 2-stroke outboard
motor. Unfortunately, the boat doesn't come with an owner manual and I
don't know when the manufacturer will mail the owner manual to me. I
need some info about maintaining this motor:

- It is a 2-stroke motor with oil-injection (this means oil is not
mixed with fuel in the tank). I cannot find anything that looks like
an oil filter. Is this normal?

- Do I expect to see a fuel filter somewhere to trap water in the
fuel? Is it a good idea to retrofit a fuel filter to the fuel line if
the fuel system doesn't come with a fuel filter?

- I am trying to locate the screw hole for draining engine oil from
the lower part of the outboard motor. I can see two screws in the
right side of the lower part of the outboard. They are a couple inches
apart, and one is above the other by an inch. Which one is the one
that I should unscrew in order to drain oil from the lower part of the
motor? Where is the vent hole for draining oil?

Thanks in advance for any info.

Jay Chan

Jay
- There is no filter to filter the 2 cycle oil.

- There usually is no water seperator unless one was added later.
Racor makes a nice unit. The actual filter element looks like an
automotive oil filter, but has a clear bowl with a drain on the bottom.
Be sure to get the filter specifically designed for outboatbord use. It
will have a 10 micron filter element.

- I never changed lower unit oil in a Merc. On an OMC they are located
just below and above the gearcase. It vents through the fill. Make sure
you use the right type of oil. Read about this as the condition of the
old oil will tell you alot about the condition of the gearcase.

Good luck with the new boat!!

John

John

wrote:
snip..

- I am trying to locate the screw hole for draining engine oil from
the lower part of the outboard motor. I can see two screws in the
right side of the lower part of the outboard. They are a couple inches
apart, and one is above the other by an inch. Which one is the one
that I should unscrew in order to drain oil from the lower part of the
motor? Where is the vent hole for draining oil?

Thanks in advance for any info.

Jay Chan

My drain hole and filler vent hole are on the starboard side of my
Evinrude...the vent about 8 inches above the drain/filler (which is just
below the prop housing).
My manual says to put a container under the lowest screw and remove it.
Then remove the 'vent' screw to enable the gearcase oil to flow out.
To re-fill, I take the small jug of gearcase oil and stick the tapered
nozzel into the lowest hole and squeeze until oil starts to flow out of
the above 'vent' hole. Then I quickly screw upper 'vent' plug back in
and lastly, screw the lower drain/fill plug in.
A tad messy...but I hope to get better after a few changes.
Manual says you can simply re-fill from top 'vent' hole...but you have
to be careful of air bubbles.

On the bottom of the lower unit near the skag you will find an oil plug,
this is to fill/drain the unit. The two plugs you mentioned up higher: The
lower one is to vent the lower unit while filling/draining, the other is to
drain water from the water pump housing.

I have a feeling that I need to buy a Mercury owner manual or a video
to know the details.

You might want to consider mixing gas and oil at a ratio of one bottle of
Merk oil to 5 gallons of gas. The bottle will tell you to mix one bottle
with 6 gallons of gas. I always mix it heavy on oil, spark plugs are a lot
easier to change than pistons and crankshafts. I have never had any
problems with this heavier mix, Merk oil burns clean and leaves only a
slight residue in the cylinders, usually it can be wiped out with a cloth
during a tear down after 30 years of hard use!

Meks oil injection has not been the most successful thing they ever did and
a lot of motors have burned up because of it. By using gas/oil mix you
eliminate that risk totally.

I didn't know that Mercury oil injection has such a problem. I will
have to research on this issue. Pre-mixing them together is not a bad
idea anyway. The Mercury motor leaks motor oil from somewhere near the
cap of the oil cup when I tilt the motor up (seem like a known problem
from other posts in this newsgroup). I have been thinking of adding
only half a tank of oil to the oil tank to avoid this problem, and
pre-mixing oil will surely avoid this problem altogether.

But this means I will need to get a large portable gas container for
mixing, right? How big a portable gas container should I get for my
boat that has a 44-gal gas tank?

I don't understand your statement "spark plugs are a lot easier to
change than pistons and crankshafts." Do you mean these:

- If we add a lot of oil, the worst thing can happen is having the
spark plug damaged and need to be replaced, and this doesn't cost much,
and can be replaced in the field.

- If we don't add enough oil, the worst thing can happen is having the
pistons and crankshafts damaged and need to be replaced, and this costs
a lot, and is not something that we can replace in the field.

The carbs have a screen filter in the cap where the fuel lines attach. An
external water separating fuel filter between the tank and the motor is a
good idea.

Thanks. I will look around to see if I can find an inline fuel-filter
and retrofit it into the fuel system. The layout of the fuel line and
the available space in the stern doesn't allow me to mount a typical
fuel filter; I will have to get an inline version.

Jay Chan

- There is no filter to filter the 2 cycle oil.

Thanks for the confirmation. Now I have one less thing to worry about


- There usually is no water seperator unless one was added later.
Racor makes a nice unit. The actual filter element looks like an
automotive oil filter, but has a clear bowl with a drain on the bottom.
Be sure to get the filter specifically designed for outboatbord use. It
will have a 10 micron filter element.

I will look for it in a marine supply store. As mentioned in my other
post, I will look for one that is inline (if such thing exists) instead
of one that requires me to mount it vertically.

- I never changed lower unit oil in a Merc. On an OMC they are located
just below and above the gearcase. It vents through the fill.

Seem like I definitely need a copy of Mercury Outboard Owner Manual
before doing the oil change.

Jay Chan

My drain hole and filler vent hole are on the starboard side of my
Evinrude...the vent about 8 inches above the drain/filler (which is just
below the prop housing).
My manual says to put a container under the lowest screw and remove it.
Then remove the 'vent' screw to enable the gearcase oil to flow out.
To re-fill, I take the small jug of gearcase oil and stick the tapered
nozzel into the lowest hole and squeeze until oil starts to flow out of
the above 'vent' hole. Then I quickly screw upper 'vent' plug back in
and lastly, screw the lower drain/fill plug in.
A tad messy...but I hope to get better after a few changes.
Manual says you can simply re-fill from top 'vent' hole...but you have
to be careful of air bubbles.

I don't get a good mental picture of how this is being done. I really
need to get a copy of the outboard engine owner manual, and then come
back to re-read your instruction.

Thanks.

Jay Chan