Replacing Yanmar SD20 Sail Drive

[Halo]

My sail drive has a problem with water getting into the oil causing an emulsion. This became apparent at he start of the season so I have changed the oil a couple of times when dried out. I simply did not have time to sort it immediately and did not want to loose the season so I just used it.
The main seals to the hull need changing as they are time expired
Now the winter is coming I want to plan a repair.
Given there has been some salt water in the drive for at least 6 months does the comittee think it would be more sensible to replace the whole sail drive?
Any thoughts, advice, experience on the repair or replacement of the unit and seals?
Many thanks in advance
Martin

 

[Tranona]

Not sure there is a time requirement for changing Yanmar seals, but I may be wrong. Not a big deal once the drive is out tho'. Think you will only find out if it is worth rebuilding when you take it down. With Volvo drives it is usually not worth it as the cost of spares makes it uneconomic. However, the price of a new unit is horrendous (at least for Volvo) and you may find a repair the better option.

 

[Slipperman]

I had the same problem earlier in the season and after trying to ignore the problem for a while eventually took the hit and had the lower seals replaced, which meant a lift out of course. The cost for the work was just over £200 - the mechanic found that the final drive shaft was slightly grooved where the outer shaft had been, but apparently there is room for the seal to be moved up (once only). This was done and so far (touch wood) it has been OK. Next time it happens, I guess I will be in for a new drive shaft, which I understand are ridiculously expensive (c £500 I believe). Hopefully your SD 20 will be OK with just new seals - replacing the lower seals does not need the whole saildrive unit to come out, just the end cap behind the prop to come off).

 

[wizard]

I had the same problem earlier in the season and after trying to ignore the problem for a while eventually took the hit and had the lower seals replaced, which meant a lift out of course. The cost for the work was just over £200 - the mechanic found that the final drive shaft was slightly grooved where the outer shaft had been, but apparently there is room for the seal to be moved up (once only). This was done and so far (touch wood) it has been OK. Next time it happens, I guess I will be in for a new drive shaft, which I understand are ridiculously expensive (c £500 I believe). Hopefully your SD 20 will be OK with just new seals - replacing the lower seals does not need the whole saildrive unit to come out, just the end cap behind the prop to come off).

exactly what I did to my SD20 4yrs ago - moved the seals up the shaft but only lasted for two years. Then I fitted speedi-sleeves over the groove in the shaft, now 3 years on all is still good.

But I still get very nervous when checking the saildrive oil colour monthly though

 

[Halo]

Many thanks for replies so far. Has anyone changed the big seals between the unit and hull??

 

[savageseadog]

Many thanks for replies so far. Has anyone changed the big seals between the unit and hull??

I've not but I'm in possession of a set of spare seals that give an insight into how they are replaced, it really doesn't look like big job. The major work involved would be lifting the leg past interior joinery.

We agreed with our insurance company that routine replacement wasn't necessary as there is an inner seal that can be easily inspected. The chances of catastrophic failure of the outer seal due to age is vanishingly small.

 

[Tranona]

Many thanks for replies so far. Has anyone changed the big seals between the unit and hull??

If you are just doing the bottom seals, question whether it is necessary to replace the main (double) diaphragm. One of the plus features of the Yanmar is the double seal, unlike the Volvo seal - but as many will report even they show no signs of failing even well past the recommended replacement date.