Yanmar saildrive - water leak management

[arsenelupiga]

Hi, I may have issues with water in saildrive. So far have been advised 3x to take out boat and fix it based on suspicion only. As I did not, saved around 3 x 3k which will go for new saildrives instead if my approach fails.

So, I made up this approach to get boat to scheduled slipping and fix it then. I am not expert on saildrives but understand physics. Instead of panicking and forking out another couple K, I want to really understand what is going on down there.
Facts:
1. Saildrive heats up when propeller running.
2. When heats up, air and oil and maybe water expand more and cause positive pressure as saildrive leg cooled by water.
3. If temp too high water may boil and cause significant pressure increase.
4. Seals fail under pressure above certain level.

assuming not that extreme scenario (3) this is how water gets in:

Oil and air expand, cause positive pressure and oil is pushed out if seal leaks towards outside.

When motor cools down : if seal works inside saildrive direction, there is lower level of oil.
If seal does not work, water comes in because of negative pressure.


Now if above is true and you realize water in saildrive this is management strategy I reckon should work fine.

1. Warm up saildrives and change saildrive oil to get water out. Repeat to get more water out.

2. Fill fresh oil. Now almost no water in.

3. Go out there, start motor, run it and then stop.

4. Go engine room and unscrew halfway dipstick so air can come in and no negative pressure.

5. When saildrive cools down, add missing oil & tighten.

6. Motor ready for next time.

This way water will not come in and you can last as long as necessary, say till next haul out.

If you see water in anyway, I guess, gotta go for slip.


Can anyone see any issues with above approach

[Captain Bill]

Item 3 is a real possibility and a problem. It happened to me. I had to use high power for about 20 minutes once (Max. Cont.) and it boiled the water in the drive leg. There was only a small amount of water in the oil at the time, just a little milky, not looking like a chocolate milkshake. It inverted every seal in the drive and blew out all of the oil. It instantly filled with seawater. By the time I got it hauled the drive required a complete overhaul to the tune of about $6K by the time yard fees were included. If you can be sure that you'll never need to use high power, you can take a chance. The drive oil I used advertised that it contained an emulsifying agent that was supposed to protect the metal if contaminated with water. It didn't help a bit after it was blown all over my engine room by the water turning to steam. Then again maybe your oil doesn't have such an agent and the seawater can start corroding the bearing right away.

What do you mean by "suspicion" ? There is either water in the oil or there's not. If there is, my advice is to haul the boat and have it repaired. Changing the prop shaft seals takes about an hour to an hour and a half. The seals cost about $125 US, If you have the parts, (oil Seal, water seal and two O-rings) It should take no more than three hours labor to do both drives. I did both of mine myself, including the complete reassembly of two autostream feathering props in 4 hours. I don't know what the going rate for a haul out in Sydney is, but I did the whole job for about $1000 including the haul out.

One other item is that yanmar uses cheap unhardened steel in their prop shafts and the oil seals wear grooves in them. At some point they will no longer seal and you'll need a new shaft. It's possible to have the old shaft turned down a few thousandths and have a chrome steel sleeve put on the shaft. I had this done about 4 years ago.

Also do both drives even if there's only oil in one!


Good luck, and if there's water in the oil do not use high power.

[sailfish2008]

facts ;
5, sail drive failure and seizing
6,repair or replace end of story :.................

[arsenelupiga]

my trouble is that oil on dipstick looks fine (i think) and do not know of reliable way to determine if water in or not.

how "milky" looks like ?

Is this milky ? Yeah, I know oil is above upper mark. But next time I checked oil was again close to bottom mark as always.

[jldunn86]

Originally Posted by arsenelupiga

my trouble is that oil on dipstick looks fine (i think) and do not know of reliable way to determine if water in or not.

how "milky" looks like ?

Is this milky ? Yeah, I know oil is above upper mark. But next time I checked oil was again close to bottom mark as always.

That looks pretty good to me, you will know milky when you see it.

I have no dog in this hunt, but if this is a typical issue with the sail drive unit. Why not vent the case to a collection bottle to let them breathe thru the temperature cycle and catch any drips before the bilge. Drill the cap and press a short copper (or other ) tube to attach tubing to etc. etc...

[Cadence]

Originally Posted by Captain Bill

Item 3 is a real possibility and a problem. It happened to me. I had to use high power for about 20 minutes once (Max. Cont.) and it boiled the water in the drive leg. There was only a small amount of water in the oil at the time, just a little milky, not looking like a chocolate milkshake. It inverted every seal in the drive and blew out all of the oil. It instantly filled with seawater. By the time I got it hauled the drive required a complete overhaul to the tune of about $6K by the time yard fees were included. If you can be sure that you'll never need to use high power, you can take a chance. The drive oil I used advertised that it contained an emulsifying agent that was supposed to protect the metal if contaminated with water. It didn't help a bit after it was blown all over my engine room by the water turning to steam. Then again maybe your oil doesn't have such an agent and the seawater can start corroding the bearing right away.

What do you mean by "suspicion" ? There is either water in the oil or there's not. If there is, my advice is to haul the boat and have it repaired. Changing the prop shaft seals takes about an hour to an hour and a half. The seals cost about $125 US, If you have the parts, (oil Seal, water seal and two O-rings) It should take no more than three hours labor to do both drives. I did both of mine myself, including the complete reassembly of two autostream feathering props in 4 hours. I don't know what the going rate for a haul out in Sydney is, but I did the whole job for about $1000 including the haul out.

One other item is that yanmar uses cheap unhardened steel in their prop shafts and the oil seals wear grooves in them. At some point they will no longer seal and you'll need a new shaft. It's possible to have the old shaft turned down a few thousandths and have a chrome steel sleeve put on the shaft. I had this done about 4 years ago.

Also do both drives even if there's only oil in one!


Good luck, and if there's water in the oil do not use high power.

Bill,

I have no dog in this hunt as someone else said. I hope the OP takes your advice. Have no experience with sail drives but sound like the same problem common to outboards and outdrive. Being able to find it on a dip stick beats finding it went changing leg oil and water pours out.

[Moontide]

Couple of comments.

JLDunn's comment is a good one about putting in a breather tube. Same concept as on the heat exchangers. I have been told that Mercruiser actually has a package that does that. The person who told me about it had problems with water coming in but solved it by putting on the "tank" above the water line so there was some positive pressure in the saildrive, and pressure relief. Guess you have to play with it (how far the tube/pipe goes into the saildrive goes) so that it does not overfill the drive.

That being said, I know of one case where the owner had knowingly operated with water in the saildrive for 5 years. He then pulled the saildrive and, since he owns a machine shop, went through the drive and mic'd the parts. He said all were within tolerances.

One of my saildrives ends up with water even right after I change the seals. After reading the posts on this thread I am going to check the shaft to see if it has gotten eaten up. Have had no other problems with the drives, even with the water in the oil. Think that is partly because I use the boat a lot so the water is constantly getting stirred up and does not get a lot of time to sit and corrode the inside.

Before paying to have the saildrive repaired you might want to consider just getting a new saildrive. Right after I bought my boat one of the cone clutches went out. The cost quoted to repair it was about 2/3rds of the cost of a new one and would only have 90 day warranty on the parts repaired. Of course neither the distributor nor the mechanic told me that it could be repaired in the boat relatively easily. Should have been a $500 repair, with no need to haul the boat to take the saildrive to his shop.

Let us know what you decide.

Bill

[Cadence]

This may be

Yanmar SD20 Saildrive - YouTube

www.youtube.com/watch?v=v1FFr8ZQtdo

- 212k - Cached - Similar pages
May 24, 2011 ... A step by step video of how to remove saildrive and replace seals. ... Vervangen manchet saildrive Volvo Penta D2-55 / MS25S - Duration: ...worth a look?

[lonesoldier0408]

Originally Posted by jldunn86

That looks pretty good to me, you will know milky when you see it.

I have no dog in this hunt, but if this is a typical issue with the sail drive unit. Why not vent the case to a collection bottle to let them breathe thru the temperature cycle and catch any drips before the bilge. Drill the cap and press a short copper (or other ) tube to attach tubing to etc. etc...

I second this approach.
Is there no way to run a copper or rubber line, to the bottom of the drive and draw off the offending water. Seems between this and the vent, maintenance could be less often.

Sent from my KFTHWI using Tapatalk HD

[GrahamHO]

I had water in my Yanmar Saildrive. The oil was milky when drained on a haul out. I got in a Yanmar mechanic who said it is a known problem. He removed the prop shaft. The seal had worn into the shaft. He took it to a machine shop and they worked magic on it by building up the problem area with a harder metal then machining it all back to original. He also replaced the seals. The problem went away and he said it will not happen again and it hasn't. Same happened to a friends Yanmar Saildrive and another workshop did the same repair. It was not very expensive and took a couple of days. The Auckland New Zealand Yanmar agents; Whitings, I'm sure would be happy to advise even if you're far away. No more problem some years later. By the way I use Mercury stern drive oil which is meant to be more tolerant of water problems. Not that there is a problem now.

[wcapital]

We've periodically had water intrusion into our sail drives as well (SD-20 on 3GM30F's) - which has most commonly happened after wrapping a line on the prop. Depending upon diameter of line, it apparently may squeeze in close enough to affect the seals, allowing some water in. However, a short time after removing the offending line, they seem to close back up and not allow more water in.

While the conventional wisdom is in fact to haul the boat and change seals and oil, we've had success with a process like you suggest - pump out all the oil you can, refill...repeat - until oil no longer is milky. [I find most easy to shine a light down into the fill hole rather than trying to tell from the thin layer on the dipstick - if it's milky that's usually quite apparent, lighter and often not uniform in color.]

[GrahamHO]

Conventional wisdom is wise! Don't mess around with sucking oil out. From memory the proper repair to my shaft was NZ$300 / 400. Plus haul out for a couple of days when I could do other work while I waited. The shaft was removed in about 20 minutes using a slide hammer and naturally undoing the various bits. I took the prop off and replaced it to save 1/2 hour labor. I'm not sure if it was hard chrome that was used. A similar technique is sometimes used on aircraft engine bits using hard chrome.

[Cadence]

Originally Posted by wcapital

We've periodically had water intrusion into our sail drives as well (SD-20 on 3GM30F's) - which has most commonly happened after wrapping a line on the prop. Depending upon diameter of line, it apparently may squeeze in close enough to affect the seals, allowing some water in. However, a short time after removing the offending line, they seem to close back up and not allow more water in.

While the conventional wisdom is in fact to haul the boat and change seals and oil, we've had success with a process like you suggest - pump out all the oil you can, refill...repeat - until oil no longer is milky. [I find most easy to shine a light down into the fill hole rather than trying to tell from the thin layer on the dipstick - if it's milky that's usually quite apparent, lighter and often not uniform in color.]

Generally monofilament takes out the seal. A lobster trap warp not so
much. The fishing line you probably would not know about.

[arsenelupiga]

Thanks for the responses. I will warm up saildrive, and change oil. SD50 can easily do in water. Then use hot plate to see if oil exploding when in contact (because of boiling water) & also wait couple of days and see if water will separate at the bottom.

That should hopefully be decisive.

Let me add that I run proplellers at max rpm for 10 min before shutting down for weekend, as advised by yanmar. I have not done this before. Next time I checked, oil level was 3cm higher. However, after using it, checked the oil and level was back to normal

So, extreme oil/air (water?) heat may have caused higher level but, just cant explain it.

I will also run idle next time before shutting down. Pressure on seals at max rpm may be too much.

[sowwaninii]

I agree with short-hauling the boat and draining oil/repair of seals. Potentially, by attempting to sucking the oil out you create negative pressue and could actually suck more water into the saildrive.