Yanmar SD20 Saildrive Oil Seals - Water in Drive

[matrix]

While sailing down Baja this past month I have noticed the oil level in my SD20 saildrive increase and the consistency of the oil to become undeniably "milky." I have to assume at this point that I need to replace the lower prop shaft seals and o-rings...

However, could there be any other source of the oil level rising besides salt-water intrusion? (wishful thinking)...Or is this just a tell-tale sign?

Today the oil poured out the top of the drive as it "hissed" and released pressure during my normal periodic drive-oil check. It's Sierra High Performance Synthetic Gear oil, used per the advice of an excellent Yanmar mechanic, hence the "avocado milkshake" appearance.

With oil looking like this (attached) is salt water intrusion a certainty? I would hate to haul out unless it was certain I needed to, but after today's over-flowing incident, the problem is getting hard to deny. Previously I had only noticed slight increases on the dip-stick level and was concerned by the change in appearance of the oil itself.

I luckily have the seals and o-rings with me, having read many of the threads on this topic here at CF before setting sail, which I am happy about but having to haul out in Cabo or Puerto Vallarta is a rough financial hit for a budget cruiser... Worth fixing for the long-term, of course.

Just Wondering if anyone has any alternative suggestions or things to check before we bite the bullet and figure out the best place to haul out quickly?

Thanks for the advice

[ggray]

Sounds like seawater intrusion to me. Here's what I did when this happened to one of our saildrives. Incidently, I think the water may have leaked past a poorly seated oring on the drain plug (the yanmar replacement oring didn't seem to me to fit as well as the original, which sounds strange).

I can't remove but about 1/3 the oil out of my SD20, using my hand, oil change pump. Did it about 9 times, with light running in between, to remove water in the oil.

Then I made an oil header tank attached to a tube through the fill cap, and mounted it a foot or so above the waterline.

It relieves the pressure differences that will occur in an otherwise unvented saildrive. The positive pressure keeps water out, assuming it is not a complete seal failure. I can check/add oil much easier as well.

[careka]

Originally Posted by ggray

Sounds like seawater intrusion to me. Here's what I did when this happened to one of our saildrives. Incidently, I think the water may have leaked past a poorly seated oring on the drain plug (the yanmar replacement oring didn't seem to me to fit as well as the original, which sounds strange).

I can't remove but about 1/3 the oil out of my SD20, using my hand, oil change pump. Did it about 9 times, with light running in between, to remove water in the oil.

Then I made an oil header tank attached to a tube through the fill cap, and mounted it a foot or so above the waterline.

It relieves the pressure differences that will occur in an otherwise unvented saildrive. The positive pressure keeps water out, assuming it is not a complete seal failure. I can check/add oil much easier as well.

Hey, that sounds like a good ide,
Do you have some photos to show us ?

[matrix]

Thanks ggray -- I appreciate the idea and I have read some of your other posts on this topic with great interest, as the idea of a header tank makes a lot of sense. I also appreciate you confirming my suspicions, as it sure does look like salt water intrusion!

I really do not want to haul out, so it sounds like your plan is well worth a try. I will use a pump to suck out as much oil as possible, using light running in between changes until it appears I have removed most of the sea water. I'll expect it to take 9+ attempts but thats so much more preferred to a haul out, as I have plenty of time.

I'll then build a header tank using some of the suggestions you have outlined here and in other posts. There is an excellent resource here of some folks who did this in the Indian Ocean, too: Sail Drives

I remember either you or someone else posting that they used a cleaned-out old Lucas Fuel Additive bottle, which I have lying around and seems like a fine choice. I am in Cabo so there should be no problem finding the fittings to make this all work...

Were you using synthetic oil when you first noticed salt water intrusion, and did you continue to use synthetic once building the header tank? 9 Changes with High Performance Gear Oil might be a little expensive, but still a lot *less* expensive than a haul out so still a great option...

After building the head tank, I will just have to add a little bit of oil from time to time, as you point out, but this might get me over the hump until my next scheduled haul out, instead of an emergency haul out right in the middle of cruising.

Thanks ggray for the excellent suggestions! If you have any other pictures of tips to share please let me know, as I will likely begin building this today or tomorrow.

[ggray]

Matrix,that is a good link. I'll study it further about what they did with the leg. But his expansion tank rig is virtually like mine, even with a valve (I use a plastic pinch valve) just above the oil fill cap.

No photos Careka, but here is what i did: the bottle I used was indeed a small Lucas fuel injector cleaner bottle. I cut the bottom off, after cleaning with acetone. I had a plastic fitting probably 1/4 npt male one end and 1/4 hose barb the other. Glued the npt end into the neck of the bottle with JB Weld, with the barb sticking out of course. The cap is the outer portion of a non toxic antifreeze gallon jug. I used a knife to scrape off the little ridge inside so it would fit better, and tried to cut a little vertical groove for air to pass.

This difference from what Matrix's link suggested is that I drilled thru the oil fill cap and stuck a 1/4 OD ss tube thru it sticking down to where the oil fill level was supposed to be. The air space I was trying to maintain probably disappears over time as air leaks out. It may no longer be needed for oil expansion as it was prior to this modification as you will now have aplace for the oil to go.
The downside to my ss tube is that the 1/4 vinyl tube attached to the ss tube wants to come off unless you really pinch it tight with 2 wraps of ss wire twisted with pliers.

Anyway, the vinyl tube connects to the barb on the tank which i mount about 18 inches above waterline with wire ties and wire tie brackets.. I have to replace the vinyl tube every other year at hauling, but it's nice to be able to see the oil going down and air bubbling up.

I have had this system on both engines now for the last 8 years or better, and had no problem. Your link warns about risk of too much pressure head on the oil seals, but I'll bet it is not as much as what can occur in the unvented saildrive at times.

[ggray]

Oh, one other thing Matrix, when I said light running, I was just a idle, and only a few minutes to mix up the good and bad oil. I got to be pretty good drawing the oil out!

I didn't have enough Amsoil synthetic, so I used the regular stuff. Previously it was synthetic.

[matrix]

Cheers ggray -- super helpful info. I am going to hopefully fix this in the next 24 hours and I will post my results here. I am also using an old Lucas Fuel Bottle, with similar fittings I've got most of it hooked up already and tomorrow will be the oil changes, I assume you just got things looking as clear as possible and then connected the header tank...

I've found a fitting that threads directly into the top of the drive like the link, but if that gives me any trouble i'll be going with the drilling of the oil cap itself as you've done.

I'll also have to switch over from Synthetic back to the regular stuff, but that will just make things simpler anyway...

Thanks a lot! I'll post my results here -- if this gets me out of doing a haul out I'll be so psyched.

[barnakiel]

Seen similar cases on other make drives. Most of the time were due to owners not changing the anodes and the drives simply corroding thru.

Looking forward to your report on how it went.

b.

[amarinesurveyor]

If you ignore the salt water getting into your gear oil, the salt WILL cause more wear on the gears and the bearings. I see this all the time when I take oil samples from saildrives. The ones that have high sodium also usually have higher than normal metal content (excessive wear).
Installing an expansion tank does not solve the problem, the only way to fix it is to change the seals.
Brian

[matrix]

b: In many cases it is due to corrosion issues, however the prop seals are a very well documented issue on the Yanmar drives and in my case, luckily, there is no corrosion at all as I have been extremely on top of the anodes, both internal and external.

marinesurveyor: I appreciate your comments however I suggest you re-read ggray's post as well as the link i've posted above. Undoubtedly to change the seals themselves is the best solution, along with the installation of the expansion tank, however as ggray wisely points out, unless the seal is completely compromised, then I may only leak a slight amount of oil out of the drive, as opposed to allowing a slight amount of seawater in (which I agree, will destroy the drive, in time). This is a short-term measure to try and mitigate damage to the drive as much as possible while delaying the financial burden of hauling out whilst in the middle of my cruising in central america. I don't doubt that the drives with high sodium content show more excessive metal content, as well, definitely makes sense, and something to keep in mind!

[matrix]

ggray: Project is underway but appearing to be working like a charm...at change #7 it's looking basically uncontaminated.... Will do another for good measure then install the header tank.... much thanks for your help. If this does not work at least the header tank is installed and we are enroute to San Blas which apparently has some of the cheapest haul out rates in Mainland Mex. Happy to have two sets of the seals and o-rings with me, having read many excellent threads on this topic here on CF and elsewhere...

Stoked! Thanks!

[ggray]

Great! Hope that's the end of your problem. I really don't understand why these aren't fitted to all saildrives.

[Sonosailor]

Gentlemen (or anybody): Love the solution, but a few questions:

1. What is a normal frequency for replacing the seals so that the risk of this problem is minimized? In my case, the boat is used 6 months per year, but with only reasonable hours on the engine (I try to sail a lot and motor a little).

2. What is the cause of the failure in your opinion? Do the seals wear, or is it more to do with the spring on the outside-facing seal rusting and making a mess?

3. How long do you think someone can go with a seal problem by replacing the top 0.8 litres of oil after every hour of run-time before getting the boat hauled? I have the problem, have commitments, and it may be months before I can haul the boat (unless it is a dire emergency)

[Sonosailor]

Here is another question: Is the gear oil cap of a particular NPT that allows this to be done reasonably easily?

Gosh, sure would like pictures of your holding tank.

[DotDun]

Originally Posted by Sonosailor

Gentlemen (or anybody): Love the solution, but a few questions:

1. What is a normal frequency for replacing the seals so that the risk of this problem is minimized? In my case, the boat is used 6 months per year, but with only reasonable hours on the engine (I try to sail a lot and motor a little).

2. What is the cause of the failure in your opinion? Do the seals wear, or is it more to do with the spring on the outside-facing seal rusting and making a mess?

3. How long do you think someone can go with a seal problem by replacing the top 0.8 litres of oil after every hour of run-time before getting the boat hauled? I have the problem, have commitments, and it may be months before I can haul the boat (unless it is a dire emergency)

1. The Yanmar Service Manual states to change the seals: if you have a problem; or everytime you disassembly. It states they have a service life of 1000 hours or 2 years.

2. ? They wear out? They are installed improperly?

3. Obviously Yanmar is going to tell you to fix immediately, but as you state, that's not always possible. One would think that 80-90w oil will give better protection than 30w that is recommended with the small engine. The thicker the oil the slower the water would separate from the oil. Since the problem would be the lower gears/bearings as the water separates, I would think frequent operation to keep the oil/water mixed would help. Of course, changing 1/3-1/2 of the oil right after running would take out 1/3-1/2 of the water also. IMO, it is certainly something that needs attention as soon as practical.