|Winterization Of Gas Engines (MerCruiser)|
Tips for your MerCruiser Engines
Taking time to winterize your boat correctly will
your boat is ready for dependable operation when Spring
Winterization should start with a good tune-up!
Haul your boat and make sure the bottom and drives are
any barnacle or grass growth. The sooner you clean or
the boat after haul, the easier it will be.
Run the engines on flush-muffs or a similar fresh
water flushing system
with good, clean fresh water for about 15 minutes each
Note all gauge readings for proper operations and
listen to the engine
for any weird noises which may be an indication of
Now is the time to address any mechanical problems that
you might suspect.
For example, if you hear a slight tapping noise and the
engine really doesn't idle
that great, your engine may seize up from
rusty water that has leaked into the cylinders, especially if you ignore this problem till spring,
The above example is actually VERY COMMON.
After you have flushed the engines on the hose it's a
to run some antifreeze through the system.
PLEASE observe any environmental laws and safety
concerns that may
pertain to the coolant/antifreeze products that you are
Please note. The next step involves sucking an
from a bucket using the suction of the water pump in
the drive unit.
If your water pump is not in perfect condition then the
might not be able to draw the water from the bucket.
This could cause an engine overheat condition which
could lead to
extensive (and expensive) damage.
Take careful note if the hose is sucking from the
bucket right away.
If you get no suction then you have a problem with the
hose, the flushett,
or the water pump.
Get a 5 gallon bucket and mix up a 50:50 batch of
antifreeze and water.
It's good to use a short (6 foot long) garden hose that
engine flushett at one end.
Make sure the bucket end of the hose stays at the
bottom of the bucket
so that it doesn't suck air!
Note: The next step can be dangerous and it is
an experienced MerCruiser mechanic perform the fogging
operation as removal
of the flame arrestor is necessary which can lead to
injury and death. The flame arrestor on a boat is
different from a cars
air filter. A boats flame arrestor prevents backfires
from exploding dangerous
gases which can accumulate in the boats bilge.
NEVER run a boat without an installed flame arrestor
unless care is taken to
prevent such explosions and fire fighting tools are
close by and in good condition
in case the need should arise to extinguish a gas or
Following and knowing about the warnings above, remove
arrestor from the carb and have a can of fogging oil
Fogging oil now comes in spray cans. MerCruiserâ€™s
fogging oil is
called Storage Seal and works great. You can also use a
of Marvel Mystery Oil if you like.
It's a good idea to have a friend on the outside of the
the garden hose and monitoring the fluid level in the
This all has to happen smoothly!
NEVER run the engine without a water supply! Not even
for 10 seconds!
Start the engine and let idle while observing the fluid
level in the bucket.
Before the bucket is empty, start to fog the engine but
don't let it stall.
Just before all the fluid is sucked out of the bucket,
engine by fogging at a faster rate.
Once the engine has stalled, stop fogging.
Reinstall the flame arrestor and plastic cover if
Some people prefer to leave the engine as is from this
We recommend that the block and manifolds be drained.
To drain the block, you will have to remove some type
of block plug
or open some type of petcock valve.
MerCruiser has used a few different types of petcocks
Some look like brass wing-nuts with a drain hole in the
Some are as simple as a brass plug.
In either case, they will be located on the side of the
usually just behind where the motor braces bolt to the
These drains can be very difficult to remove sometimes.
Also, when removed, they might be plugged with rust and will not drain.
If the passage is plugged then take a thin screwdriver
and ream the hole clean.
Next you will need to drain the exhaust manifolds.
The bottom of the manifolds will sometimes have
petcocks or brass plugs.
Sometimes the manifolds wont have drain plugs and in
you simply need to remove the water hose from the
bottom to drain it.
The large water hose on the front of the engine should
also be removed
as it will puddle water even after the block is
Get some good anticorrosion spray such as LPS#2 or
Corrosion Guard and spray the entire engine with a good
while trying to avoid the plug wires and belts.
Make sure your bilge is clean as well as the rest of
Remove the battery, charge it up and store it in a well
dry and safe area so it's not sitting on the ground.
Remove the drain plug so melted snow won't sink your
boat on the trailer!
Remove the speedometer tube from the back of the
blow through the tube to expel any water in it.
Change your outdrive lube with whatever the factory
If you had noticed ANY water in the old drive oil then
outdrive in for service right away. Don't wait or your
will be extremely higher due to the rusting of
Remove the prop and grease the prop shaft.
Grease the transom zerk fittings and steering system.
Store the drive in the down position to prevent water
in front of the prop and cracking your case. Also, it
U-Joint bellows from getting distorted.
Your local marine store should have additives for your
fresh water system.
Drain the pipes and hoses. Also empty any sea-strainers
On inboard engines.
Excerpted from www.sterndrives.com