saildrive failed

mjak42 · #1 (**permalink**) 05-11-2010

Boat has been stuck in marina for 12 months, while I worked on her, ran motor every couple of weeks in gear,went to take her to slipway today, could only get 1.5 knots, figured prop had barnacles etc, and perhaps could not open right up,(folding prop) managed to get 3/4 way there then lost all forward motion, took her out of gear and I had an oil slick coming out the stern, its an SD20 behind a 3 GM yanmar 27hp, anybody got a guess what could be wrong.

sailingdog · #2 (**permalink**) 05-11-2010

Just curious, when was the last time you changed/inspected the zincs on the saildrive? These units have had a history of corrosion problems, and that would be worsened if you haven't changed or inspected the zincs. If the saildrive leg corroded through, you could lose all the oil from the lower drive unit.

pedcab · #3 (**permalink**) 05-11-2010

Quote:

Originally Posted by sailingdog

Just curious, when was the last time you changed/inspected the zincs on the saildrive? These units have had a history of corrosion problems, and that would be worsened if you haven't changed or inspected the zincs. If the saildrive leg corroded through, you could lose all the oil from the lower drive unit.

Agree.

It can also be a failed prop shaft seal.

Either way, and if your system has lost the hability to propel the boat I suspect that you're in for a very large repair bill...

DwayneSpeer · #4 (**permalink**) 05-11-2010

I don't know if your's is like my Volvo saildrive but a while back mine leaked a bit due to the seal on the oil drain plug. It didn't fail completely, but it could have been your problem. If so it's a real easy fix. Keep your fingers crossed.

sailingdog · #5 (**permalink**) 05-11-2010

Just FYI, there is an official Yanmar bulletin regarding saildrives, including your make/model IIRC. Keep your receipts, as your repair may be covered...

mjak42 · #6 (**permalink**) 05-14-2010

Slipped boat today, anodes were still fine, no problem with leg, after waterblast clean up everything looked fine, a couple of hours later noticed some oil seeping out of the driveshaft seal, turned prop and you can hear the gears turning inside, so problem must be further up, question, with the lower leg if you remove the 8 bolts will the lower leg slip off, cannot see why not!! I only have a schematic of the lower part of leg not the top part, does anyone have one.

pedcab · #7 (**permalink**) 05-14-2010

Quote:

Originally Posted by mjak42

Slipped boat today, anodes were still fine, no problem with leg, after waterblast clean up everything looked fine, a couple of hours later noticed some oil seeping out of the driveshaft seal, turned prop and you can hear the gears turning inside, so problem must be further up, question, with the lower leg if you remove the 8 bolts will the lower leg slip off, cannot see why not!! I only have a schematic of the lower part of leg not the top part, does anyone have one.

Bear in mind that just because you can hear the gears turn it does not necessarily mean they're not crippled in any way... Furthermore if you confirm a leaky shaft seal it most certainly means water must have got inside the gear-box so an extensive inspection is advised...

mjak42 · #8 (**permalink**) 05-14-2010

Went down today, put into gear, prop turned right through to motor, no problem at all, was hard to turn due to engine compression, but no sign of problems, gearbox oil is milky due to lower seals. I am at a loss. prop was closed when we hauled it, but as soon as the waterblaster came in contact it opened straight up, he beat me to it, I was going to try by hand but he did it from a distance with not a lot of force, just waved it passed.

Livia · #9 (**permalink**) 05-17-2010

I'm very curious if anyone knows more about this because, at least on our saildrive, my understanding was that the hull sail drive seal is for water ingress into the boat, not into the transmission (here is a pic).

If the bolt at the bottom of our drive was leaking we could get water in the oil, or if we had such bad corrosion (zincs fail or we hit the drive and cracked it) that the sail drive itself wasn't watertight we could also get corrosion, but if only the hull seal failed I thought we would get water leaking into the bilge.

rbarkas · #10 (**permalink**) 05-18-2010

Quote:

Originally Posted by Livia

I'm very curious if anyone knows more about this because, at least on our saildrive, my understanding was that the hull sail drive seal is for water ingress into the boat, not into the transmission (here is a pic).

If the bolt at the bottom of our drive was leaking we could get water in the oil, or if we had such bad corrosion (zincs fail or we hit the drive and cracked it) that the sail drive itself wasn't watertight we could also get corrosion, but if only the hull seal failed I thought we would get water leaking into the bilge.

The big rubber seals are to keep water out of the boat. You are correct.

There is also a seal that fits around the prop shaft at the bottom of the saildrive. Sometimes this gets leaky. We had some fishing line that got wrapped around the shaft and worked it's way in and shredded the seal.
We didn't notice any oil in the water but we did see significant 'milkiness' in the saildrive oil.

Took our trusty Yanmar expert about 30 minutes to change it on the hard and then we changed the saildrive oil 2-3 times till we got rid of any hint of milkiness.

All has been good since.

Hope I understood your question correctly and that this info helps.