Water in saildrive - bad luck or?

[Eric Jan]

We have a pair of Twin Disc SP60's with 27hp engines in front of them.

And once again we have 1 saildrive with water in it. Here is the quick history.

Before that everything was good for years.

May 2023 - full-ish service of saildrive for new diaphragms, prop shaft sleeve (*sleeve by design) was sanded (mistake by mechanic probably) and everything put back together.

June 2023 - we noticed water in that saildrive.

June/July 2023 - in a different place (due to cruising) we got hauled out and a new sleeve, seals, o-rings for prop shaft part, etc was placed.

July-Sept 2023 - everything looked good (checked regularly)

March 2024 - we are getting ready to move again. prop and saildrive where fouled pretty bad. I ran the engine in gear (slow) for couple min to warm up the engine for oil replacement of engine.

A week or so later cleaned the props/drive/bottom in the water and ran the engine a bit longer.

Water in the saildrive, milkshake.

Replaced the oil (sucked out on top, put new ATF Dexron 2 in), ran for 5 min, checked a day later... milkshake.

Did not notice any lines or other obstructions except marine life.

So - bad luck?

I have spare parts: new sleeve, o-rings and seals for propshaft part.

next steps are probably to be hauled out in the next 1-2 months or so, but is the battleplan to replace the above spareparts a good one or what do you guys think?

[skipperpete]

Do you know if the Technodrive seals have stainless steel garter springs to maintain lip pressure? if they’re just regular automotive seals with carbon steel springs, they have a fairly short life exposed to seawater and the inner (second) seal only keeps oil in, not water out, once the outer seal starts to leak, it’s not long before water gets into the oil. I’m not familiar with the SP 60 replaceable seal track ( I mostly use Speedisleeves) but the usual drill is to use a sealant between a seal track and the shaft where it sits even when it’s a press fit…..if water can get in, it will find a way. I guess you’d also have to consider the joint between the lower and upper sections of the Saildrive as being a possibility, loose bolts? Cracked flange? Badly installed oring? Finally, the most common cause of Saildrive seal damage is…… fishing line.
There remains the possibility of a porous casting inside the water passages and across to the oil side, very rare but worth thinking about if all else fails.

[barnab]

For your March 2024 problem growth may be the culprit, it may have destroyed the outer seal (but that's just a wild guess)...


I'm a fan of oil header tanks, the slightly increase the oil pressure inside the saildrive so if there is a leak the oil will slowly leak out (visible by the level of oil in the header tank) instead of the water leaking in. There are tons of descriptions, here is one example: Sail Drives


I would try to get the water out asap, the gears don't like salt water...

[Tupaia]

I assume that having 2 engines with 2 sail drives you are referring to a catamaran.
There is something to consider, I had the same problem and replaced the seals many times. The seals are not rated for zero psi so if the level of oil is equivalent to the level of water on the outside, taking account of the difference in viscosity it is possible for them to leak even at anchor just due to small wave action resulting in pressures at or around zero psi. I finally solved the problem having installed replacement sail drives by fitting header tanks to the sail drives. It only requires a tiny amount of positive pressure to resolve the issue.
The issue rarely occurs on boats (monos) where there is always a large pressure difference due to the SD's being much deeper in the water.

[Eric Jan]

Thank you all for the responses this far, so list till now:

- fishing line (aka bad luck )
- fouled/growth

- sleeve pressed on without sealant (I will check with dealer if this is necessary)
- bad seal (not stainless)

- bad upper/lower leg connection.

- figuring out a header tank (will read up on this, I like this as its also easier to see oil level I guess)

[Eric Jan]

Originally Posted by skipperpete

Do you know if the Technodrive seals have stainless steel garter springs to maintain lip pressure? if they’re just regular automotive seals with carbon steel springs, they have a fairly short life exposed to seawater and the inner (second) seal only keeps oil in, not water out, once the outer seal starts to leak, it’s not long before water gets into the oil. I’m not familiar with the SP 60 replaceable seal track ( I mostly use Speedisleeves) but the usual drill is to use a sealant between a seal track and the shaft where it sits even when it’s a press fit…..if water can get in, it will find a way. I guess you’d also have to consider the joint between the lower and upper sections of the Saildrive as being a possibility, loose bolts? Cracked flange? Badly installed oring? Finally, the most common cause of Saildrive seal damage is…… fishing line.
There remains the possibility of a porous casting inside the water passages and across to the oil side, very rare but worth thinking about if all else fails.

I hope its the seal as that would be an easy fix.

I will check the sleeve sealant point as I'm pretty sure its pressed on (with heat etc).

The upper/lower leg - with bad o-rings (or worse), of course anything is almost possible, but if it was good for from the june/july - sept 2023, how big of chance do you recon that is?

[skipperpete]

Originally Posted by Eric Jan

I hope its the seal as that would be an easy fix.

I will check the sleeve sealant point as I'm pretty sure its pressed on (with heat etc).

The upper/lower leg - with bad o-rings (or worse), of course anything is almost possible, but if it was good for from the june/july - sept 2023, how big of chance do you recon that is?

Yes, the most likely point of entry would be the propshaft seal, check the garter spring when you pop the seal out and maybe ease the spring gently out of the new seal and test it with a magnet.

[FPNC]

Do not overlook the o-ring around the drain plug at the bottom of the drive.
It is cheap insurance to replace the o-ring every time the plug is removed. Most people do not do this.

[DirtPete]

Originally Posted by FPNC

Do not overlook the o-ring around the drain plug at the bottom of the drive.
It is cheap insurance to replace the o-ring every time the plug is removed. Most people do not do this.

^^^This, they are also really easy to pinch when screwing in the plug.

[Eric Jan]

Originally Posted by FPNC

Do not overlook the o-ring around the drain plug at the bottom of the drive.
It is cheap insurance to replace the o-ring every time the plug is removed. Most people do not do this.

I will make sure we check that as well! Good point!

Also we have an appointment for April 24th to haul out, so fingers crossed.

[Eric Jan]

Seemed that the inner seal that faced inward was damaged. The one facing to the water still looked okay.

Now my question how?

According to the mechanic here its installation error by the previous mechanic in the other place. But I cannot really imagine that.

So, bad luck?

(we are back in the water and will check the oil again tomorrow).
(the dirty one is just from falling on the ground)

[Tupaia]

Not surprised it leaked if it looked like that. Definitely forced in rather than pressed in square.

[Eric Jan]

Originally Posted by Tupaia

Not surprised it leaked if it looked like that. Definitely forced in rather than pressed in square.

Tnx for sharing your thoughts! It was good for months though (but yeah that doesn't mean it was good to begin with )

[skipperpete]

It looks like the sealing lip got caught on the edge of the pressed on seal track collar, is that sealtrack sharp on the edge or does it have a smooth surface for the seal to ease over as the carrier is gently persuaded into place? I can actually understand how it took a while for the water to get to the oil… or the oil to the water…..that’s a tricky problem that I’ve not seen on Volvo, ZF or any of the Yanmar saildrives, maybe there’s a service tool to help avoid this on the SP60 ( like the sleeve that fits in the Volvo propshaft seal to avoid more or less this same problem). Glad to see that you got it fixed.

[Eric Jan]

Originally Posted by skipperpete

It looks like the sealing lip got caught on the edge of the pressed on seal track collar, is that sealtrack sharp on the edge or does it have a smooth surface for the seal to ease over as the carrier is gently persuaded into place? I can actually understand how it took a while for the water to get to the oil… or the oil to the water…..that’s a tricky problem that I’ve not seen on Volvo, ZF or any of the Yanmar saildrives, maybe there’s a service tool to help avoid this on the SP60 ( like the sleeve that fits in the Volvo propshaft seal to avoid more or less this same problem). Glad to see that you got it fixed.

Well, when the prop was off you could see the milkshake come out. So the fluids went both ways.

I didn't see anything inside that would be sharp enough to really do this. And this was the inner oil side seal. The outside seal that might be touching water looked okay (probably wasn't 100% as it let oil out as well.)

Which maybe does leave installation or some strange issue.