SD50 oil leak no water intrusion

[jasonburke360]

Hello,
First post but have been looking previous ones over.
I have two SD50 sail drives by Yanmar, 2008. Port is leaking gear oil when underway, traveling for more than an hour. I pulled some and its gear oil and is not emulsified. Oil has been on the top of the saildrive and leaks down into space below engine. Engine oil is fine. Had a tech take a look and he noticed the gear oil was dark in color and lower viscosity compared to new gear oil.
Looking for advice and possible next steps.

[SailingHarmonie]

I'm quite confused by your question. it seems your next steps are pretty obvious.

1. Fix the leak,
2. Change the oil.

Did the tech not have advice about HOW to fix the leak?

Assuming you are right in your description of the location of the oil leak, it seems one of the seals in the pinion shaft assembly is leaking. Since you have to take it apart to do this, you just replace them all.

Is that what you are looking for?

[skipperpete]

Originally Posted by jasonburke360

Hello,

First post but have been looking previous ones over.

I have two SD50 sail drives by Yanmar, 2008. Port is leaking gear oil when underway, traveling for more than an hour. I pulled some and its gear oil and is not emulsified. Oil has been on the top of the saildrive and leaks down into space below engine. Engine oil is fine. Had a tech take a look and he noticed the gear oil was dark in color and lower viscosity compared to new gear oil.

Looking for advice and possible next steps.

Your “tech” seems to have described the sometimes used “Quicksilver gear oil”

[ggray]

Make sure the SD oil is not over-filled. I had oil pushed out, presumably past the fill cap, but if overfilled it would be worse.

But once I installed header tanks, it hasn't happened again.

[Tin Tin]

Two most likely issues. Overfilled oil causing higher than normal pressure in the sealed gear case. This may also result in oil being forced out through the prop shaft seals. Remedy is to make sure that the correct dip stick is in use (there is a Yanmar service note on this) and/or do the vented header tank, plenty of this topic and applies to most sail drives and even stern drives (In fact the modification can use the Mercruiser header tank)
Second issue is the shaft seal is either worn out or the more likely cause is a groove cut into the input shaft by crud caught in the seal which will need repair with a speedi sleeve (cheapest and quickest DIY option) - or re-machining or in a really bad case a new shaft. There are You tube vids on doing the speedi sleeve ($20) + new seal, repair and a Yanmar service note on it as well. Beware the mechanic that says the engine and drive needs to be removed from the boat for a few thousand dollars, this job can usually be done in situ in about 4 hours with the right tools.

[Tin Tin]

For reference:
https://wesailhanse.se/370_documents...level_sd50.pdf


https://dealer.yanmar.com.au/bulleti...eedisleeve.pdf

[skipperpete]

Thanks TinTin, thats all really good info.
Elsewhere on the forum there’s a thread about the propshaft seals and shaft repair by a really savvy cruiser/engineer, he posted recently about about applying a layer of tungsten carbide to the seal track area after using speedisleeves with varying degrees of success.