Changing Saildrive Shaft Seals - Drain Plug Removal or Not?

RichardS

RichardS

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I need to change the lower oil / water seals and O-rings on both my Yanmar SD20 shaftdrives this Spring.

I know that the prop / anode assemblies will come apart easily as when I rebuilt them in 2014 I deliberately omitted the Loctite after the fiasco removing them on that occasion!

The only part which might cause removal problems are the drain plugs which have been in place for a several years and have been well painted over with Trilux. I do have the necessary O-rings but it has occured to me that, provided I use a bucket to catch the oil when I undo the two large bolts and pull the shaft out, I could probably just leave the drain plug undisturbed.

I cannot envisage ever needing to remove the drain plug as I will refill the leg with good quality EP gear oil which will not need replacing until the seals start to leak again which I hope will be in another 7 years. :)

Has anyone done the seal replacement without removing the drain plugs and is there any disadvantage in doing it this way?

All observations gratefully received!

Richard
 
Along with shaft seal leakage the plug could be leaking a little water inward even if it holds the oil when hauled out?
I open, clean, reseal with sikaflex or similar rather than o-ring as I have found on my VP saildrive that the ring distorts and gets damaged when tightening.
 
I found the easiest way to remove the drain screws on my saildrives was to use the largest best fitting screwdriver, one with a square section that I could get a spanner on. a trolley jack under the screwdriver to hold it in place and they both came out with no dramas.
 
RichardS said:
I need to change the lower oil / water seals and O-rings on both my Yanmar SD20 shaftdrives this Spring.

I know that the prop / anode assemblies will come apart easily as when I rebuilt them in 2014 I deliberately omitted the Loctite after the fiasco removing them on that occasion!

The only part which might cause removal problems are the drain plugs which have been in place for a several years and have been well painted over with Trilux. I do have the necessary O-rings but it has occured to me that, provided I use a bucket to catch the oil when I undo the two large bolts and pull the shaft out, I could probably just leave the drain plug undisturbed.

I cannot envisage ever needing to remove the drain plug as I will refill the leg with good quality EP gear oil which will not need replacing until the seals start to leak again which I hope will be in another 7 years. :)

Has anyone done the seal replacement without removing the drain plugs and is there any disadvantage in doing it this way?

All observations gratefully received!

Richard
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I think Id try removing the drain plugs as the first option. Impact driver is normally recommended for outboard engine gearbox drain screws.
 
Slowtack said:
Along with shaft seal leakage the plug could be leaking a little water inward even if it holds the oil when hauled out?
I open, clean, reseal with sikaflex or similar rather than o-ring as I have found on my VP saildrive that the ring distorts and gets damaged when tightening.
Click to expand...

It is interesting that you use sealant rather than the O-ring as I've not heard that before. However, your concern about the O-ring distorting is the kind of thing that worries me.

Many years of working on cars and bikes has taught me that if something is working well and doesn't need planned maintenance then it's generally best not to disturb it .... and I know my drain plugs are working well because the film of Trilux over the plugs is unbroken so they cannot be leaking.

Put it this way .... if I do replace the O-rings and, by chance, one of them does start to leak shortly after replacement once the boat is back in the water, I would need to spend another £500 to haul out and replace a 10p O-ring. :(

So far it appears that everyone removes the drain plug but perhaps we will hear from someone who has tried my suggestion.

Richard
 
For what it's worth, the drain plug on Ariam's S130 saildrive came out nice and easily back in the autumn. I came prepared with a spanner that fits the screwdriver shaft for extra leverage, and an impact driver, but in fact it just undid with normal pressure on the screwdriver alone. The O-ring looked convincing to me. But I take your point that if you don't disturb it, it definitely won't leak :)

Pete
 
Spirit of Glenans said:
It's my understanding that you're supposed to refill the oil through the drain plug....?
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That's how you do it on an outboard.

Not heard any suggestion that you do a sail drive like that. Filler with dipstick on the top box isn't there?

RTM!

.
 
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Spirit of Glenans said:
It's my understanding that you're supposed to refill the oil through the drain plug....?
Click to expand...

As Vic says, there is a combined filler plug and dipstick at the top of the saildrive. I have very easy access with my cat so can look straight down into the filler hole and don't even need the dipstick as I can just look at the level. This also has the advantage (?) that I can see the oil in one saildrive has turned from clear yellow to Starbucks Mocha during the last season. Having said that, I believe the seals are the original ones from when the boat was new 7 years ago.

As an aside, last season all at the same time and after 7 years the battery in the Raystar RS125 GPS failed, the oil seal in the Quick windlass failed and the seals in the SD20 have failed. If you ever wondered why charter companies sell their boats after 6 years when they still appear to be in very good condition, wonder no longer! :(

Richard
 
Richard , let me know how you get on , I am planning to do my sail drive seal in May before heading back to Croatia . Any tips or problem and I do the same if I get to do mine before you mate .
Oh and I had to replace my oil seal on my quick windlass end of last year , 6 years old .
 
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On my previous saildrive (Volvo 110s) after the struggle getting out the original drain plug, I substituted the old one for a stainless bolt with an Allen key head. This makes subsequent removal a doddle.
 
philwebb said:
On my previous saildrive (Volvo 110s) after the struggle getting out the original drain plug, I substituted the old one for a stainless bolt with an Allen key head. This makes subsequent removal a doddle.
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An o ring needs a groove to function reliably. If you cannot machine one in the correct dimensions and tolerances to suit the o ring then be careful with this idea.
 
sailaboutvic said:
Richard , let me know how you get on , I am planning to do my sail drive seal in May before heading back to Croatia . Any tips or problem and I do the same if I get to do mine before you mate .
Oh and I had to replace my oil seal on my quick windlass end of last year , 6 years old .
Click to expand...

I'll come back with my experiences as it doesn't seem that many people have tried my suggestion. I'm going to do the first saildrive without removing the drain plug and see what happens. If there are problems I'll do the second one using the traditional method. :)

Richard
 
prv said:
For what it's worth, the drain plug on Ariam's S130 saildrive came out nice and easily back in the autumn. I came prepared with a spanner that fits the screwdriver shaft for extra leverage, and an impact driver, but in fact it just undid with normal pressure on the screwdriver alone. The O-ring looked convincing to me. But I take your point that if you don't disturb it, it definitely won't leak :)

Pete
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I read this thread just hours after having the drain screw removed - and I couldn't do so and needed an engineer to pop by and release it.

Any recommendations for a reasonably priced impact driver that would do this job safely without damaging the screw - seems to be a huge variety, from £5 to £250 on Amazon/eBay. Also I suspect needs quite an unusual screwdriver bit - long but thin flat head.

Now worried about refitting it. How tight should it be - to be secure/watertight but not damage the O Ring?

PS Also on the job list is trying to clear shellfish blocking from the inlet waterways. Needed unblocking with a welding rod down through the open seacocks at the end of last year - impressive inward rush when cleared the block!
Not really impressed with sail drives so far
 
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I used a large screwdriver with square shaft, vicegrip attached to the shaft so you can maintain upward pressure while faithful assistant rotates the vicegrip
 
Just to update the thread ....

I took photos but due to a camera (or operator) malfunction none of them have come out!

Anyway, I removed the saildrive shafts without first removing the drain plugs and just drained the oil into a container. The oil from the port engine was like mocha coffee as I thought so it was clear that both shaft seals had gone.

When you look inside the saildrive after removing the shaft assembly, it is interesting that the drain plug is in a raised section of the saildrive casting and the drain hole is at least a centimetre above the bottom of the casting. In effect there is a dead space which will never drain out through the drain plug so my conclusion would be to leave the drain plug undisturbed and simply remove the shaft if you intend to change the seals as that is the only way to get all the oil out.

The oil in the starboard saildrive was actually pretty clear. However, as I'm on the hard it's worth changing both sets of seal. When I stripped down the shaft the gap between the two seals was full of seawater so the outer seal had gone and it was only a matter of time before the inner seal went. I have rebuilt both shafts and filled the gap between the two seals with waterproof grease. I don't know whether this will make any difference to the longevity of the seals but I can't see how the extra seal/shaft lubrication will make things any worse.

The shafts, bearings and bevel gears all seemed to be in very good condition which is encouraging.

Richard
 
RichardS said:
Just to update the thread ....

I took photos but due to a camera (or operator) malfunction none of them have come out!

Richard
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I did get one picture after all. This is 50% oil from the saildrive with the shot seals and 50% from the one which was just on the point of going!

Not a pretty sight compared to the nice clear yellow of the GL5 I poured in. :)

IMG_3956.JPG


Richard
 
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