Reading the shop manual for an OMC cobra outdrive (4.3 L, V6 engine)
the section re draining the outdrive oil has me confused:

There are 3 screws 1) a dip stick on the very top of the outdrive 2) a
fill port on the side of the OD about 1/2 way down 3) the drainport on
the very bottom of the OD.

To add oil the manual says if I remove the dipstick on the top and
then remove the lower plug at the drain port, only 1 tablespoon
"should" come out of the drain plug and a "hydraulic lock" will keep
the oil in the outdrive. It says to screw in the fitting from the oil
container and pump it until the oil is at the line on the dip stick.

But ...... it also says to drain and change the oil remove the dip
stick and the drain plug and all the oil will drain out.

What am I missing ? That makes no sense.
When I changed the oil I removed the lower drain plug and it ALL
drained out as expected.
I did not have quite enough oil and had to go to the boat shop.

When I followed the procedure to ADD a little more It made a mess
because much more than 1 tablespoon drained out. I got it up to the
correct level but it was pretty messy.

What am I doing wrong?

Kip

"kipmc4" wrote in message
...
Reading the shop manual for an OMC cobra outdrive (4.3 L, V6 engine)
the section re draining the outdrive oil has me confused:

There are 3 screws 1) a dip stick on the very top of the outdrive 2) a
fill port on the side of the OD about 1/2 way down 3) the drainport on
the very bottom of the OD.

To add oil the manual says if I remove the dipstick on the top and
then remove the lower plug at the drain port, only 1 tablespoon
"should" come out of the drain plug and a "hydraulic lock" will keep
the oil in the outdrive. It says to screw in the fitting from the oil
container and pump it until the oil is at the line on the dip stick.

But ...... it also says to drain and change the oil remove the dip
stick and the drain plug and all the oil will drain out.

What am I missing ? That makes no sense.
When I changed the oil I removed the lower drain plug and it ALL
drained out as expected.
I did not have quite enough oil and had to go to the boat shop.

When I followed the procedure to ADD a little more It made a mess
because much more than 1 tablespoon drained out. I got it up to the
correct level but it was pretty messy.

What am I doing wrong?

Kip

The "hydraulic lock" will occur if only the lower drain is removed and the
other ports are tight in place. This prevents air from entering the drive
and replacing the interior volume from the drained oil, thereby stopping the
oil from draining. I've never owned an OMC Cobra drive, but here's how I
would do it. First remove the lower drain plug, leaving the other two ports
tightly covered. The hydraulic lock should minimize oil draining from the
port. Then attach the fitting from the oil container to the lower drain
port. Once connected, remove the dipstick on the top of the outdrive, then
pump enough oil into the bottom port to bring the level up to the
appropriate mark by repeatedly checking the level with the dipstick. When
done, replace the dipstick and tighten it securely to re-invoke the
hydraulic lock. Remove the fill attachment and quickly replace the lower
drain plug. That oughta do it. The manual you have was either poorly
written, or you read it wrong.

"RG" wrote in message
...

"kipmc4" wrote in message
...
Reading the shop manual for an OMC cobra outdrive (4.3 L, V6 engine)
the section re draining the outdrive oil has me confused:

There are 3 screws 1) a dip stick on the very top of the outdrive 2) a
fill port on the side of the OD about 1/2 way down 3) the drainport on
the very bottom of the OD.

To add oil the manual says if I remove the dipstick on the top and
then remove the lower plug at the drain port, only 1 tablespoon
"should" come out of the drain plug and a "hydraulic lock" will keep
the oil in the outdrive. It says to screw in the fitting from the oil
container and pump it until the oil is at the line on the dip stick.

But ...... it also says to drain and change the oil remove the dip
stick and the drain plug and all the oil will drain out.




Be very careful when filling a Cobra drive as many people get it wrong and
quickly ruin the expensive gears in the upper unit.

This is for the regular Cobra Stern Drive, not the later Cobra SX Drive with
the cone clutch.

The following paraphrases the factory service manual. Be very carefull if
relying on an off-brand manual, they are not always accurate.

Drain the gearcase through the bottom drain hole and reinstall the screw
plug when done. Remove the MIDDLE screw and fill through that hole until the
oil level reaches the upper mark on the top dipstick. Tighten the dipstick
screw and quickly remove the oil filler and install the middle screw. It is
important to run the drive a few minutes (hook up a flusher first!) turn it
off, then wait a few more minutes for the oil to settle. Recheck the
dipstick for the proper oil level before using the boat on the water.

There are cavities inside the lower part of the gearcase that could trap air
if filled from the bottom hole and not the required middle hole. The
incorrect oil level will drop when the cavities purge the air while the
motor is running and the upper gears will then run dry when the oil level
drops and "flare out" causing a loss of power when they fail and a super
expensive repair bill. This happens quite frequently in the spring after
someone not knowing the proper procedure, changes the gear oil in a Cobra
Stern Drive.

Bill Grannis
service manager

Thanks Bill and RG.

I learned 3 things:

1) The manual was written poorly and I should leave the top dip stick
in place when I'm removing either drain plug and then once installed
remove it as I fill the outdrive.

2) Drain from the bottom hole but fill from the middle hole contrary
to what my boat mechanic says!!.

3) Check the oil level after running at low power for a few minutes
to be sure all air has been removed and the level is correct.


Thanks
Kip