# Notes on changing Volvo Saildrive main hull seal



## colemj (Jul 10, 2003)

I just changed our saildrive main hull boot seals, as well as the rear oil seals on the engines (no better time to get to that than when the tranny is removed). A couple of observations:

1. Our 18yr old main hull seals look almost new. There is a slight bit of checking on the fold of them. All of my experience tells me that Volvo's 7 year replacement requirement is hooey. I have searched far and wide for a failure of this seal and only came across a single instance. In this instance, a 12yr old seal developed a rip in it. The failure mode was that during heavy seas (he was going around Cape Horn!), a bit of water would squirt up through it. He said it was very manageable and didn't leak in calmer conditions. I suspected that because the design and make of this seal, any failure would not be catastrophic and would be easily managed without danger or hurry. There is far too much fear around this.

2. When you order the hull seal kit, it comes with the main seal, two O-rings, a gasket, some seizing wire, and the secondary fairing seal. One of the O-rings is quite a large one and I'll be damned if I can figure out where that goes. It is not shown in the included instructions, nor in the exploded drive schematic, nor did I remove a similar O-ring in the disassembly. It is not found on the 110S, 120S-ABCDE, or 130S schematics. I thought it was included as a mistake in the package, but the second package contained one also. Volvo is messing with their customers. It's probably something really funny in Swedish, but doesn't translate well.

3. If you decide to do this job, take the extra 5 minutes and change the oil seal on the input shaft (the shaft that couples to the engine). You won't get another chance at it without removing the tranny again, and the part is relatively inexpensive. This seal isn't included in the kit, so you will need to order it. The official workshop manual instructions for removing this shaft seal is to jam a screwdriver in it and pry it out. Not a technique normally recommended for this type of job, but it works quickly. The workshop manual also says to remove the entire housing and gear and put it in a vise for removing the seal. No need for that - just leave the whole thing in place and use a screwdriver.

Since the saildrives need to be disassembled for this, it was a good time to change their prop shaft oil and water seals. I did some research and cross referenced the Volvo Stefa saildrive shaft seals with more easily obtainable SKF seals. The equivalent SKF seal is *CR SKF V51 12456*, also sometimes listed as *CR-12456*
I bought them for $6.94 each versus Marinepartsexpress price of $32.79 each.

I also changed the rear oil seals on the engines. I bought Perkins Perama M30 rear oil seals from Trans Atlantic Diesel for $32/each. This Perkins engine is the exact engine as our Volvo MD2030. Marinepartsexpress wanted $64 for the Volvo seal.

BTW, Marinepartsexpress is the cheapest place I found for Volvo parts. However, I now have a list of alternate sources for equivalent parts much cheaper than Volvo (no doubt that oil seal would have been less expensive at a tractor supply place, but I needed it quickly).

Mark


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## KBuckley (Sep 17, 2008)

Great info. Thanks for the post.

From an owner of an 8 yr old saildrive.

Sent from my Sony Tablet S using Tapatalk


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## replusted (Dec 17, 2001)

I definitely have to agree with you colemj that the 7 year recommended replacement interval is extremely conservative. I replaced my sail drive seal when I purchased my boat. It was 14 years old at the time and looked just like the new one. Those seals are made of very tough rubber and I can't imagine that it could fail even after 25 years. However, my insurance company insisted that it be replaced before they would write a policy. Thanks for your post. Good information.


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## Jaramaz (Aug 9, 2013)

OK, it is wellknown that the sail drive seal lasts much much longer than the 7 years. Why is Volvo then recommending 7 years?

To understand this we must think (sorry): the lifetime of physical parts is stochastic. If the average lifetime of the seal is (let's say) 25 years, then the probably for failure after only 10 years is maybe 1% (think normal distribution if you like; all numbers just invented, they are examples). 1% failure is probably too high for both customers and for the manufacturer reputation, thus to improve this the manufacturer improve the seal to get an average lifetime of (again, let's say) 25 year and recommends chaning the seal after 7 years. Then the probably for failure before these 7 years has decreased to 0.05%, resulting in that nearly no one has heard about any such problem. 

Saildrive manufacturers do not want any bad reputation on this. There are already too many saying: Oh, I would never dream of having a large hole in my boat (many threads on this  ). 

OTOH, saildrive makers do not want user to have to change seals very often, users would then tire of the solution. 7 years and a good reputation is a very good combination - for such long period the problem is often handed over to next user/owner, and many just skip replacing after 7 years, knowing very well that he probability for failure is very very low. 

/J


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## BarryL (Aug 21, 2003)

Hey,

Thanks for your post. This winter I had the seal changed on my 2002 boat. After 14 years the seal looked great. I will wait 15 years until I change i again (if I even have this boat). I paid a mechanic to do the work. He said it was straightforward and everything appeared to be in good condition. He did disassemble the sail drive leg to change the seals. He told me was amazed at the amount of marine life growing inside the leg. He gave me a small bucket half filled with mussel shells, clam shells, oyster shells and all sorts of stuff. He was surprised the engine didn't overheat. I told him that last season i couldn't operate the engine over 3000 rpm without it getting too hot. This season i can now run at 3400 rpm without any problems. 

Barry


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## colemj (Jul 10, 2003)

I don't like bringing the cooling water in through the drive leg for that reason (among others). We have separate thru hulls for engine intake.

Mark


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## colemj (Jul 10, 2003)

Whoops, I posted too soon about the prop shaft seal cross reference before I had the seals in hand. 

While these seals are a replacement in size and fit, the seal bodies seem to be mild steel instead of stainless used in the Volvo Stefa seals. This was not listed in any of the info I saw.

At least they are magnetic, while the Volvo ones are not - so I am guessing mild steel vs. something more appropriate for salt water.

So I would not recommend using them in salt water. Looks like I wasted $14, and will have to dip back into the Volvo shark tank for seals.

Mark


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