SD20 leakage problem

[zachs]

Hi all,

I have a 1GM10C with SD20 drive installed in a Columbia 26 MKII. 2 weeks ago I went to check the oil level in the SD20 and there seemed to be some backpressure which made oil come up out of the oil fill. Not too much, but enough to know that something wasn't right. After thinking about this for a bit I finally came to the conclusion that water must be leaking into the oil from somewhere down below. Things that led me there were 1. Backpressure on oil. 2. slightly milky consistency of the oil. Relating to the milky consistency the oil had been like this for some time (at least 8 months).

Later last week I had the boat hauled for paint, zinc's, and other maintenance and I figured I'd replace all the seals in the lower unit. (Including the gasket around the oil drain plug). Nothing seemed too out of the ordinary, meaning no obviously broken seals.

So I have thrown the whole thing back together and am hoping for the best at this point.

I'm looking for advice on any other items I should check before putting her back in the water? Or if any one has seen this behavior on this drive.

Thanks in advance,
Zach

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[Rohorn]

Hi Zachs....I just replaced the two 1gm10/sd20 drives in my cat. 12 years old. I've put in new 2gm20f/sd20 s . I changed the drives as well because for years the oil has appeared milky over the last 6 years and I considered that with the power increase I'd be happier with new drives.
I was told by the Yanmar agents in Piraeus that, if there was a seal problem the drives always leaked water inwards, never oil outwards. Also with the 1gm motor delivering so little power through the drive there was no real risk of a breakdown.
I did change out the shaft seals on one drive but it made no difference. The oil still became milky. The shaft was not worn or badly marked.
I did wonder if there was provision for a breather to allow for expansion and conraction without pressurising the oil, but the agent said it wasn't necessary. He also said that saildrives were not popular in Greece and he sold very few, and had little experience with them!
From all this I'm awaiting with interest to see if my new drives have milky oil at the end of the summer. If they do, I'll regard it as normal and carry on a as usual! Sorry to have no clear info.....I don't think we are alone on this.
There's a good site www.Yanmarhelp.com which may help.
Cheers....R

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[Rick]

Have seen the milky problem from both poor seals / gaskets, and also as result of pinholes in the alloy - where a copper antifouling was previously used!

My experience with SD20's and Volvo 120S's is that they don't leak if the seals and gaskets are in good condition, and the shaft is mirror smooth and defect free. Can't remember about the SD20, but 120S legs often go milky if the fishing line cutter if faulty and allows line or weed to get behind it and pick up the seal.

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