Saildrive Oil Change

[svenskflicka]

Doing the first oil change on the Yanmar SD20 since I got the boat, does this look normal? Do you think there is water in it? Also only about 1.75 quarts came out? That's a lot less than the spec'd 2.3qts.

[a64pilot]

No, that does not look normal.
Normal should be just pure oil and nothing else, maybe a little bit of glitter being wear metals.
Water is usually emulsified in oil and looks like milk, ever been to a machine shop and seen some of the coolant used?
Your has strange brown stuff in it, and I don’t know what that is.

[svenskflicka]

Originally Posted by a64pilot

No, that does not look normal.
Normal should be just pure oil and nothing else, maybe a little bit of glitter being wear metals.
Water is usually emulsified in oil and looks like milk, ever been to a machine shop and seen some of the coolant used?
Your has strange brown stuff in it, and I don’t know what that is.

Hmm, here's another photo from when it was coming out.

[a64pilot]

The milky strands do indicate a little water, not much, but it’s salt water.
The brown stuff in the first photo I have no answer for.

[svenskflicka]

Originally Posted by a64pilot

The milky strands do indicate a little water, not much, but it’s salt water.
The brown stuff in the first photo I have no answer for.

Where could water be entering?

[a64pilot]

I don’t own a sail drive, and have never worked on one, but assuming they are similar to an outboard, the water usually comes into an outboard through the output shaft seal, the seal under the prop.

However hopefully someone with more knowledge that me will hopefully post, cause I would take no action based on what is said as it’s just a guess really.

I think water intrusion is common on a sail drive, and what you have I wouldn’t think is a big deal. I would change whatever seal is indicated, but I’d seriously doubt any damage has been done.

After repair an outboard is pressure tested for leaks, I’d assume a sail drive would be the same?

[ggray]

I have two SD20s, and maybe 16 or more years ago was faced with the same problem.

I questioned the unvented sail drive housing. Varying pressure differentials depending on internal temperature, water temperature, temperature when oil was last checked. As deep in the water as the shaft is, and oil being lighter than water, there would be more pressure outside than inside.

So I then installed header tanks connected to a tube thru the filler cap. Header tanks are maybe two feet above the top of the sail drive, well above the waterline.

So now there is always slightly more pressure inside than outside the hub seals.
Also easier to check oil level , and to add oil.

First, though, I pumped out as much oil as I could (about 1/3 capacity), ran the engine in gear a few minutes, and repeat for a total of 9 times. Cleaned up nicely.

[Sberg]

Svenskaflicka
I have sd20’s and had a similar colour oil come out on my last haulout. I had noticed the change a while before but was not convinced on water intrusion. I tested by getting some new gear oil in a clear jar and adding a drop of water at a time and shaking together. I was interesting seeing how little water was needed to get the oil to change to what you have. It also made me not so worried about damaging the gearbox by leaving it for a month till my haul out.
The mechanic at the yard we hauled out said it looked like a little bit of water intrusion, time to change the seals.
I removed the props and had a bit of interesting time removing the seal housing.
It was the first time I had done a seal change so I didn’t know the tricks and the amount of force needed to get them out. Second one was easy.
On removal of the shaft, I noticed a slight wear ring (on the shaft) where the outer seal sits. This could have allowed the slow ingress.
I also read a lot about the differing pressures that ggray describes above and think that that is a very likely scenario.
I plan on installing a header tank system in the future. I can’t see any draw backs of having a header tank.
If you need any help/advice when removing the housing, PM me.

[Rapanui]

It looks from the photos that you have a small amount of water in the oil as others have said. Not too much of a drama as this is a well reported 'feature' of SD20s and numerous threads on CF and elsewhere with plenty of examples of boats running for long periods with water in the oil without problems. The general concensus is that this 'feature' is caused by heating the saildrive when operating causing expansion of the oil and air in the drive followed by cooling and consequently contraction causing a lower pressure allowing water to be sucked past the seals.

Several people have tried a fix which reportedly works by venting to a header tank filled with oil. It may be the extra head of oil or the fact the drive is now vented which fixes the problem.I have never been brave enough to just drill a vent hole in the filler cap and find out.

We have 2 off SD20s and this was a perennial problem when we had the boat in charter, along with several other boats fitted with SD20s in the charter fleet and occurred on new saildrives when we re-engined. I should point out that the charter management team lifted all boats and replaced the seals in a yearly routine. In the end, they were advised to run the SD20s with the oil at the minimum level, i.e. just touching the tip of the dip stick and no higher. Our problems and those of others in the fleet disappeared and we now change the seals on a 2 yearly cycle.

[Compass790]

If I ever had a saildrive I would definitely go the vent & header tank way. Better system to avoid water intrusion. Yr oil is not a bad case by any means. I've seen a few in the yard changing oil much worse without having trashed the unit.

[svenskflicka]

Originally Posted by ggray

I have two SD20s, and maybe 16 or more years ago was faced with the same problem.

I questioned the unvented sail drive housing. Varying pressure differentials depending on internal temperature, water temperature, temperature when oil was last checked. As deep in the water as the shaft is, and oil being lighter than water, there would be more pressure outside than inside.

So I then installed header tanks connected to a tube thru the filler cap. Header tanks are maybe two feet above the top of the sail drive, well above the waterline.

So now there is always slightly more pressure inside than outside the hub seals.
Also easier to check oil level , and to add oil.

First, though, I pumped out as much oil as I could (about 1/3 capacity), ran the engine in gear a few minutes, and repeat for a total of 9 times. Cleaned up nicely.

Wow, thank you all for the replies! This place never ceases to amaze me.

What type of reservoir tank did you use?

[ggray]

I made tanks out of small bottle of Lucas Fuel Injector cleaner that I had.

https://www.ebay.com/itm/263919186888

Epoxied a 1/4 MNPT X 1/4 barb fitting in the neck after cleaning thoroughly w/ acetone, and cutting the bottom of the bottle off.

The cap was the outer portion of a child-proof cap from a gallon of pink boat/rv antifreeze. I cut a little groove on the inside lip to let air pass, as it is a snug fit. (If Lucas changes the size of their bottles, would have to find something different.)

Drilled a 1/4 hole where the dipstick had been in the filler cap, and pressed a 1/4 ss tube in the hole.

Threaded a plastic pinch valve on the hose connecting the two in case the cap needed to be removed when the tank is full.

FWIW, I use Amsoil marine gear lube which they claim tolerates up to 10% water. Can't hurt.

[UFO]

Not sure if the attachments loaded or not - But they are from a boat I recently looked at - Should make you feel at ease

[svenskflicka]

Originally Posted by UFO

Not sure if the attachments loaded or not - But they are from a boat I recently looked at - Should make you feel at easeAttachment 188583

Attachment 188584

Whoa, yes thanks! We went with Amsoil this time. When I finally get the boat to its forever home I'll look into installing a reservoir. I'm thinking maybe one of those outdrive gear oil tanks that mercruisers have.

[ggray]

Originally Posted by svenskflicka

Whoa, yes thanks! We went with Amsoil this time. When I finally get the boat to its forever home I'll look into installing a reservoir. I'm thinking maybe one of those outdrive gear oil tanks that mercruisers have.

Funny, I almost mentioned that the Mercruiser tank you found is exactly what I had ordered years ago!
But when it wasn't shipped when promised, I had to come up with something FAST.
30 minutes later I had in my hands what I previously described. It is smaller, but big enough, so easier to mount and not be in the way. And lots cheaper!

I can't remember, but isn't the Mercruiser tank black where you can't see the oil level?