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Old 30-04-2008, 09:16   #31
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Originally Posted by Strygaldwir View Post
Alan;

The sail drive is basically the transmission and a unit that extends through the bottom of the boat and you attach the prop to. The drain is at that bottom of this leg. You would have to attach a fitting to the bottom, route the tube up and i imagine put a hole in the bottom of your boat to route the tube up where you could get to it. I'd have several issues with this, but I don't think that is what you meant. In the SD40 Yanmar put a tube internally within the leg. You pressurize the leg this forces the gear lube out.

What I am doing is just doing partial changes ever 50 hours. I suck as much as I can out, run a little bit, suck more out. So I get a partial change. When I have the boat hauled for painting, I'd do a full change then.

Silly but

Keith
To do a partial saildrive oil change, what would you use to suck out the fluid?
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Old 30-04-2008, 09:24   #32
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Any turkey baster type thing, or what I like to use in any fluid transfer operation:

The little squeeze bulb from an outboard fuel hose line. Stick in in the saildrive from the top and change out a half a liter of oil at a time. (The saildrive holds about 2 liters).

You can only suck out the 1/2 liter because you can't get the tube of your "sucker" down past the initial well of oil where the dipstick is.

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Originally Posted by candycat View Post
To do a partial saildrive oil change, what would you use to suck out the fluid?
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Old 30-04-2008, 09:48   #33
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I am wondering if the oil is warm? That you might be able to use the Jabso hand pump with the smaller tubing? Also if the oil is diluted with water this pump may help, and reach much further down the leg of the unit?
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Old 30-04-2008, 11:33   #34
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Originally Posted by imagine2frolic View Post
I am wondering if the oil is warm? That you might be able to use the Jabso hand pump with the smaller tubing? Also if the oil is diluted with water this pump may help, and reach much further down the leg of the unit?
I used a tube the size of a drinking straw.

I couldn't find any spot to shove it any deeper, although I know there is one in there *somewhere*
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Old 30-04-2008, 17:39   #35
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I use a baister. Wonderful things to have on the boat. I use one for topping up fluids in the battery, one for getting that last bit of water out of the bilge and one just for other misc. stuff.

Oh, and my wife has one too. I don't have a clue what she uses it for...
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Old 01-05-2008, 14:40   #36
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Ok, here's what I now know about Yanmar SD20 saildrives:

There are actually 4 seals, not 2.

There are two O-rings that are wrapped around the housing the prop shaft comes out of. These are large diameter, but small in thickness. These two O-rings, acting as a set, are one of your seals to keep the water out. These could be replaced by beaching your cat if the lower unit can be separated easily and pulled from the housing. Me? It took me 30 mins to get them apart.

Ok, that is *some* of the seal. The other seals are on the shaft itself, and the shaft spins while these seals make contact with the shaft and housing that supports the shaft. These seals are more difficult to replace (read *very* difficult). I had to order a nut that is permanently frozen on the shaft to keep this assembly together, as well as the seals. You have to get that frozen nut off, then put on a new one. It was a bear getting that part apart and getting to the additional set of seals. This could *not* be done at low tide, due to the fact that I needed parts and didn't know what I needed until I had the assembly out of the main housing.

That's what's inside a Yanmar SD20 saildrive.

BTW: My gears in there were looking brand new even after 20+ years of service. Other than the seals, they are truly rugged little devices. There is very little chance of them breaking, I think.

Also, now that I've seen inside, the method of changing 1/4 of the gear oil from the top filler at every 25 hours (instead of all at every 100 hrs) seems like it would work just fine and cause no damage.

**The above will make more sense once you have your saildrive apart.
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Old 02-05-2008, 07:23   #37
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Thank you so much for all the good information
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Old 05-05-2008, 08:21   #38
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Finally got a hold of the break away diagram for the SD 20/30/31 lower gear housing. The two pressed in oil seals are the important ones to change if your oil is milky. Yanmar says they get alot of DIY people just changing out the rubber O rings at haul out then get the same water intrusion after splash, a case of penny wise pound foolish. The oil seals ARE the ones that have failed when you get water intrusion. The good news is that to press these seals out and back in is a simple ten minute job for someone with a press. This is not a low tide job as I said earlier. All being equal once these seals are properly replaced they should give plenty hours of long service. The 100 hour intervals that Yanmar does qoute is a big joke at my Yanmar service place, unofficially of course. But they do also state to make sure you replace that little O-ring on the drain plug at the same time. As far as changing out a portion of the lower units oil at each engine oil change the Yanmars guys kinda laugh at me for being a little too anal about it. But I still do it, I can only get so far down the unit until I'm probably hitting the drive shaft bearings. It might not help but it can't hurt. But as Sully said after 20+ years of service these are rugged units if taken care of. When I pulled mine apart they looked in like new condition after 12+ years of hard service 7000+ hours. So I guess except for the zincs which are hefty anyways, I'll regulate the major oil change out at haul out time to do bottom work, changing the four seals each time might be prudent regardless of present condition, it's gotta be alot cheaper than pulling a Cat back out six months later to do it anyways.
If anyone wants that lower gear housing break away diagram let me know.
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Old 05-05-2008, 14:04   #39
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Andy I sent those diagrams to your E-mail I hope you got them.
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Old 05-05-2008, 14:19   #40
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Good post, Tellie.

Although I've "been there" and seen the guts, a nice diagram would be a good thing to have around to keep things fresh for next time there is an issue.

Do you want to post it up in the gallery or right in this thread?

Thanks!

PS: I don't know if those seals are a 10 minute job with the press. Maybe if you have immediate access to all the parts for the lower unit. See, there is this nut (looks more like a ring with notches) that goes around the shaft and keeps the entire lower unit assembly together. A dent is hammered into this nut to lock it on permanently. This nut must be broken off before you can open up the lower unit assembly and get at those press seals you are talking about. A DIY, even a mechanic, would have some trouble first getting this ring/nut off, then ordering a new one. You always have to order a new one, since it is hammered into place and a notch is created in it to keep it in place while everything is spinning and torquing inside the unit.
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Old 05-05-2008, 14:29   #41
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I would post it here if I knew how, I'll try to figure it out. But I'd be more than happy to E-mail them to you Sully.
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Old 05-05-2008, 16:31   #42
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Hi Tellie,

Thanks for the diagrams. VERY helpful when ordering parts to know these part numbers.

Here are the diagrams, resized a bit to reduce file size. Enjoy!

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Old 05-05-2008, 17:54   #43
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Quote:
Originally Posted by ssullivan View Post
Good post, Tellie.

Although I've "been there" and seen the guts, a nice diagram would be a good thing to have around to keep things fresh for next time there is an issue.

Do you want to post it up in the gallery or right in this thread?

Thanks!

PS: I don't know if those seals are a 10 minute job with the press. Maybe if you have immediate access to all the parts for the lower unit. See, there is this nut (looks more like a ring with notches) that goes around the shaft and keeps the entire lower unit assembly together. A dent is hammered into this nut to lock it on permanently. This nut must be broken off before you can open up the lower unit assembly and get at those press seals you are talking about. A DIY, even a mechanic, would have some trouble first getting this ring/nut off, then ordering a new one. You always have to order a new one, since it is hammered into place and a notch is created in it to keep it in place while everything is spinning and torquing inside the unit.
Good point, I insisted that all the seals were replaced on recommendation of my surveyor and my broker when we hauled the boat before I finalized the deal when I bought her. I helped the mechanic pull both hubs out but he took them to his shop to change the oil seals. He was back in about 45 min. The Yanmar guys told me today that they do it in 10 minutes but their new thing is that if they can't get the whole job they won't just press the seals if you bring it to them. So yeah having all the parts would be nice. I'll remember the nut and order a few before I take this job on myself. I wonder if you just couldn't buy an old fashioned nut cracker/buster to break that sucka off. Might be worth adding to the tool box.
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Old 06-05-2008, 03:16   #44
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Yup...

From our handy new parts list here, that nut is part #45.

Thanks again for the part list. I'm sure this will save a lot of people a lot of time.


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Good point, I insisted that all the seals were replaced on recommendation of my surveyor and my broker when we hauled the boat before I finalized the deal when I bought her. I helped the mechanic pull both hubs out but he took them to his shop to change the oil seals. He was back in about 45 min. The Yanmar guys told me today that they do it in 10 minutes but their new thing is that if they can't get the whole job they won't just press the seals if you bring it to them. So yeah having all the parts would be nice. I'll remember the nut and order a few before I take this job on myself. I wonder if you just couldn't buy an old fashioned nut cracker/buster to break that sucka off. Might be worth adding to the tool box.
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Old 29-04-2010, 11:20   #45
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I know this thread is a little old, but maybe I'll catch somebody with some experience. I just found Mocha Coffee in my port saildrive.

1. Are you guys saying that a DIYer will need access to some special nut and a "press" to do this job, and shouldn't attempt it without an extended period available on the "hard"? What is required to break/loosen this special nut? I thought the seals were in the back plate, and the shaft stayed where it is.

2. Somebody just told me that the seals should be bedded into the aluminum with "Blue RTV Silicone Gasket Maker, by Permatex, to minimize differential metal corrosion. He feels the failure could start as galvanic corrosion. Any feedback on that?

3. The seals have a "U" cross-section. I understand that the "U" of both seals are meant to face the seawater, not the oil. Can you confirm?

4. Assuming I am now too nervous to do it myself, anybody got a reference for a good saildrive mechanic in Chaguaramas, Trinidad?

Thanks folks.
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