Stern Drive Fluid Change, Other Maintenance

[PITBoat]

I'm draining mine this evening, after checking it the other day and finding it pretty dirty. There wasn't any water in it, and I was pleased to find hardly any metallic material on the tip of the drain plug, so I'm hopeful that the condition of my drive is good. PO had no records and I don't remember when/if he mentioned the last change date.

Going to try to lube the "steering ram" and "actuator valve fitting" before hopefully taking it out tomorrow to test out my new tach.

I started to take off the fuel/water separator filter the other day, but wasn't prepared to catch the gas that appeared to be going to drain. The date on that is from 2016.

 

[MRS]

When you do change the water/fuel filter make sure and fill with gas before installing.

 

[HT32BSX115]

I'm draining mine this evening, after checking it the other day and finding it pretty dirty. There wasn't any water in it, and I was pleased to find hardly any metallic material on the tip of the drain plug, so I'm hopeful that the condition of my drive is good. PO had no records and I don't remember when/if he mentioned the last change date.

Going to try to lube the "steering ram" and "actuator valve fitting" before hopefully taking it out tomorrow to test out my new tach.

I started to take off the fuel/water separator filter the other day, but wasn't prepared to catch the gas that appeared to be going to drain. The date on that is from 2016.

Ensure that you refill correctly. If it's a Dog-clutch Cobra, DO NOT fill it from the bottom drain port!

 

[PITBoat]

I filled it from the fill port this morning; the pump instructions said from the bottom, but the book said from the filler which made more sense.

The PS actuator valve thing was barely reachable - the zerk faced the back.

 

[HT32BSX115]

I filled it from the fill port this morning; the pump instructions said from the bottom, but the book said from the filler which made more sense.

Good job! (I hope "Fill Port" in your book means the "middle" one)..........The "book"also says to do initial fill with the dipstick resting on the threads which basically overfills slightly.

However you do that, just ensure you over-fill a little and after running long enough to warm it up, check it and top-off (through the dipstick stick hole is ok then)

My previous King Kobra drive was "serviced" by 2 different "dealers" where they filled it wrong both times and both ended up replacing the drive. The first one right away, the second one shortly after threatening to "lawyer-up"

Every so often, someone here fills a Cobra wrong and asks why the drive seized......we all wish we could catch everyone before they do that!!

Regards,

Rick

 

[Lou C]

http://www.crowleymarine.com/support/omc-tech-articles.html
look in here....

 

[PITBoat]

Yes, I filled through the middle one. I put in the suggested 2qts and it worked out perfectly.

The Crowley Marine link says you can top off through the "gauge opening" (dipstick hole). Seems like you could just fill from there from the start, but I guess not since there is a port just for filling.

 

[HT32BSX115]

Seems like you could just fill from there from the start

NO NO NO Moose Breath!!!


It's VERY important to fill from the "Fill port" because there's a bubble "trapped" when you do that!

It floats to the top eventually when the fluid gets warm/hot, and thin, when it warms up...........and "floats to the top, assuming there's enough......... " The level drops to a point where it still covers the upper gears.

If not........The upper gears, end up "uncovered" .......... and "dry".........then you "spend money" because the upper gears self destruct rather quickly.....................


many Cobras have been replaced because of this.

 

[Lou C]

Agreed you must do it the way the instructions say because in order for the correct amount of oil to get in air must be able to get out. If you were to use the top hole for all the filling air would be trapped inside and you would never get the correct amount of oil in.

 

[HT32BSX115]

The Crowley Marine link says you can top off through the "gauge opening" (dipstick hole). Seems like you could just fill from there from the start

"Topping Off" is a FAR cry from filling after draining.

If you were to remove the top cover on any Dog-clutch cobra and look inside when it's properly filled with oil, you would actually see the top gears almost completely submerged in oil.

Then, if you were drain a little .......maybe 1 cup or so, you would see that it takes VERY little to uncover those gears at the top

Once you get the level to below where those gears are submerged, during operation, they'll get VERY hot and will self destruct quickly.

The bubble that can be trapped either when the drive is initially filled from the drain hole.......OR the top (dipstick-hole) is large enough to uncover the gears when the oil heats up........ where the big bubble (and other smaller bubbles) finally float to the top.........then the gears don't have enough oil around them to prevent overheat in that area.

When you fill from the fill port, there's still bubbles trapped (but not the big one) .......That's why OMC requires filling to FULL with the dipstick screwed-OUT all the way, resting on the top of the threads. ("Allowing for a slight over-fill")

Pouring in up to a cup or so after that is acceptable because you're only filling the area you see in the picture above. There's no place left to trap bubbles.

Lou, do you happen to have a picture of a Dog Clutch Cobra with the upper cover off that's full of oil?

It would also be interesting to see a good picture of one that is filled "wrong" to see where the oil level actually would be (after the bubble floats to the top)

Cheers,

Rick

 

[Lou C]

I don't have a pic because I've never had to take that top cover off in the years I have owned it but judging by the length of the dipstick, I think the gears are fully covered when properly filled.
After filling with the dipstick laying in the hole, then screw it in and quickly remove the pump and replace the fill plug with a new gasket (should be changing all 3 of the gaskets, drain & fill are the same, the dipstick one is bigger). Then unscrew the dipstick and allow the level to stabilize for a while. Re-check and add a bit more thru the dipstick hole if needed.
BUT, just to be on the safe side:
I will also run the boat on the water hose for a bit and then re-check after the re-fill before putting the boat in the water, just in case some more trapped air was released and the level went down a bit.
Having owned the Cobra a bit over 15 years, doing it this way one problem I never had was low drive gear oil level. All I did was follow what was in the owners manual lol.

 

[PITBoat]

Good info...