Yanmar SD20 Saildrive Oil Seals - Water in Drive

[Cotemar]

Originally Posted by TabbyCat

Thanks, that's what we were hoping. Any chance you could e-mail the pdf to me?
Sailor 'at' tabbycat.us
Thanks!

To large to send in e-mail (19meg)

You can download the Yanmar SD20 Saildrive Workshop Manual from here.

http://www.yanmarmarine.co.uk/pdfs/s...al/EPB5547.pdf

[pagmd]

are these seals replacable by the average Diy at haulout?

[MC41]

Noticed slightly milky oil at the last haul out -- assuming that we have an oil seal problem as well. Does anyone know specifically what parts need to be ordered to complete the oil seal change?

Cheers!

PS Working link to SD20 service manual can be found here:

http://www.yanmarmarine.co.uk/pdfs/s...al/EPB5547.pdf

[Rapanui]

In an earlier posting i mentioned that the company that charters our boat with had been living and coping with this problem for some time on pretty well every boat with SD20s. There now is a simple solution that has been advised to them by Yanmar. Apparently the oil level and dipstick marks are too high and this is preventing the units venting properly and hence ingesting water. The solution advised by Yanmar was to lower the oil level to the bottom of the dipstick. This has cleared the problem with all the SD20 boats both monos and cats.
I should point out that they routinely change the prop shaft seals every year and this fix will not work if the seals or shaft are worn or damaged.
I would suggest that those affected should contact Yanmar for confirmation and who knows you might even get a replacement dipstick.

[Rapanui]

Forgot to mention that this fix has been proven over nearly 2 seasons now of intensive chartering on a significant number of boats

[ggray]

Originally Posted by Rapanui

There now is a simple solution that has been advised to them by Yanmar. Apparently the oil level and dipstick marks are too high and this is preventing the units venting properly and hence ingesting water. The solution advised by Yanmar was to lower the oil level to the bottom of the dipstick. This has cleared the problem with all the SD20 boats both monos and cats.
.

I don't think lowering the oil level will allow venting as I don't think there is any place for it to vent. However, more air space will certainly give more space for the oil to expand into, and on the other side, create less vacuum when the oil contracts. That would help.

But I still think the expansion tank located above the waterline gives the best protection against water intrusion. The shaft seals are what, about 2 feet or more below the waterline? And resisting that water pressure on the inside is maybe 1 1/2 feet of oil, which has a lower specific gravity than water. Then there are swings between added pressure or a partial vacuum inside the leg combined with that. Seems to me that just makes the seals work more.

[MC41]

The Yanmar SD20 service manual makes this sound like a fairly serious operation. Is anyone aware of a well-documented tutorial anywhere online? We'll be forced to do this job at our next haul out in Shelter Island, Panama, and I don't yet know if we'll be able to find good mechanical help there!

[Captain Bill]

I just had a quick look at the sd20 manual. The oil seal replacement looks very similar to the ones I just did on my SD40s. It was not hard. It took me 4 hours to do both of them and that included reassmbly of my feathering props. The props actually took longer than the seals. I didn't have the "special tool" so I located some stainless steel flat washers just slightly smaller than the OD of the seals and carefully centered them and pressed them into the housing using the yard hydraulic press. Be careful that the washers don't touch the side of the housing and press slowly. I was sort of lucky with the dimensions of the SD40 seals. Their OD is 53mm and a 2" washer is 50.8mm. You might have harder time getting a match. Getting the old ones out was abit harder than putting the new ones in because you have to be very careful not to scratch the housing. I used some brass punches and a rubber mallet to drive them out. That was the scariest part of operation. You might be able to buy an oil seal puller at an autoparts store, but I didn't have access to one.

Good luck

[MC41]

Captain Bill Thanks for the details, very helpful. I just went through this process on my 2 SD20s down in Quepos, Costa Rica.

Overall, fairly straightforward. We ended up using brass punches and a small hammer to remove the seals but it was a bit nerve-wracking as you said.

A few notes for anyone attempting this for the first time:



-You can access the oil seals without taking off the lower gear, this is not clear from the service manual. You will not need the "special socket wrench." Simply remove the bolts from the bearing cap and pop it off and the shaft assembly will slide out exposing the seals, which are pressed into the "rear cover." Pushing out the old seals was definitely the hardest part of the whole job.

-You do not need the "special tool" to press the bearings. The new ones actually go in quite easily. What you might need, at most, is a 50mm cylinder to press in the new seals. Ours, once well-lubed, went in more or less by hand. We finished by pressing with a 50mm cylinder that we had machined, but this may have been unnecessary.

Here are the Yanmar parts you'll need, for each SD20 saildrive. Prices are from Marine Pro in Florida who was extremely fast on the delivery.

x2 196313-02591 Oil Seal $5.28
x2 24321-000950 Oil Seal O-ring $2.48
x1 24341-000125 Plug O-Ring $0.89

Good luck!

[Dragon Lady]

Thanks for the info guys, I think I'll get a plastic rod to drive out the seals to avoid the angst of using a metal one.
Just wondering how much wear is acceptable on the shafts?

[Sonosailor]

For those who have gone the route and installed an elevated reservoir, would you consider listing the parts you used, and a picture and part description for the reservoir? Love to see the different ideas.

[ggray]

I should be at the boat next weekend, and can take a picture.

Someone will probably help you sooner.

[slug]

Locally I see the bareboat charter fleet change saildrive seals every year

Not expensive to change seals

[skipperpete]

Originally Posted by Dragon Lady

Thanks for the info guys, I think I'll get a plastic rod to drive out the seals to avoid the angst of using a metal one.
Just wondering how much wear is acceptable on the shafts?

You should polish the area on the shaft where the seal lips run and if they are badly worn you can move the position of the outer seal in the housing by relocating the split spacer that resides between the inner and outer seals so that the outer seal runs on an unmarked part of the propshaft. If the grooves are very bad, a thin stainless steel “Speedi-sleeve” can be installed but it’s a tricky job putting the sleeve on properly.
Here’s a pic of the tool to get the old seals out, a bent screwdriver will work too. Check the garter springs with a magnet, the inner seal can be a regular automotive oil seal but the outer has a stainless steel spring to resist corrosion. It’s ok to use a bit of gasket sealant if the seal housing is corroded in the area where the outer seal sits..... but not too much.

[ggray]

My header tank consists of an inverted Lucas fuel injector cleaner bottle with the very bottom cut off, and a plastic fitting glued into the mouth with a 1/4" barb end sticking out. A 1/4" clear vinyl tube connects to the 1/4 " SS tube I pressed into a 1/4 inch hole I drilled through the top of the fill cap.
For the cap of my header tank I used the outer portion of a 1 gallon pink antifreeze jug. Fits snuggly, so I cut/ scraped a slight groove on the inside to allow air to pass.

I also threaded a pinch valve on that vinyl tube to keep from making a mess if for some reason I needed to remove the cap when the tank had oil in it. That hasn't happened as I just add oil to the header tank.

I now have a picture of the header tank, but I find it difficult to post here. Suggestions welcome, or just PM your email if you want me to send the photo.