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Hi
Has anyone changed the main seal around the sail drive. I know it showed how to do it in PBO some years ago but I cannot find the article Any info would be helpful.
Dazzer
Not a task to be undertaken lightly. I’ve just had the saildrive diaphragm on my 2002 vintage B32 ‘Another Fantasy’ replaced; it required the removal of the engine to make sufficient space for the gearbox and saildrive unit to be lifted out. Once removed the work necessary to replace the diaphragm and make good the onset of corrosion on the surfaces where saildrive and gearbox join together was complex and time consuming, and I had the job done by a Volvo-trained marine engineer. Interestingly the old diaphragm, once it had been cleaned up, was virtually indestinguishable from its replacement part. No sign of any deterioration, cracking or fatigue; the corrosion was of much more concern to me as, had it been left, its effect over time would have become much more serious. Having seen the work involved it’s not a job that I would recommend as a ‘do it yourself’ unless you really know what you’re doing and have access to lifting tackle and a comprehensive tool kit, including a torque wrench.
I read the PBO article, although it makes the job sound reasonably straightforward the reality is somewhat different….
The choice is yours…good luck!!
Ian Culley
B32 Another FantasyI replaced our diaphragm (Bav36) last year after 9 years. As said above, the difference between old and new was hardly noticable! However, the diaphragms have the date of manufacture on and if you did have a problem would the insurance pay up? I changed ours for peace of mind despite the ridiculous cost of a rubber doughnut!
It is fairly difficult and involves undoing all the connections to the engine and moving it forwards about 4 inches (on wooden blocks, etc.) The saildrive needs the removal of the prop, the lower propeller shaft and the outer rubber seal. Its a good time to also replace the lower oil seals on the propeller shaft. The casting holding the lower bearings is sometimes hard to get out. Only then will you get the saildrive out from behind the engine into the boat. It will not drop out of the bottom of the boat.
With the saildrive out you now dismantle the lower part of the saildrive and get the diaphragm off it. The corrosion, mentioned above, comes between the rubber diaphragm on the upper and lower parts of the saildrive. On our boat it was not at all bad. You are advised not to use silicone sealant, of anything between the diaphragm and the saildrive parts so have not a clue as to how the corrosion can be reduced. It’s a bit fiddly getting the gasket and rubber ring in the right places and torquing up the bolts. We found that someone must have had the drive apart before, as there were no locking wires holding the bolts in! (Professionals!!) If you decide to change the lower oil seals you will need drifts or a press to get them out.
Then you have to put it back into the boat. Getting the engine and saildrive fitting together can be a pig. You need someone under the boat to fiddle with the prop shaft to align the splines to the engine. Also before you put the two together make sure the electrical insulation between the two is working otherwise you will have corrosion problems. (If you get professions to do the job, I would check this with a meter before you pay them!)
Then you fit everything back on the engine and hopefully everything works.
One thing I wish I had done was to put in a new oil seal at the top of the saildrive. If you have oil on the top of the present diaphragm it’s a good chance this seal is leaking a bit and dropping through the bell housing.
Perhaps, now you can decide if it is DIY or not. Best of luck.How is the electrical insulation achieved?
Electrical insulation of saildrive.
The bellhousing is isolated from the engine by plastic washers under the heads of the bolts, a plastic tube that spaces the bolts in the middle of the larger holes and a big plastic gasket. The attachment in the centre of the flywheel has rubber in it that insulates the drive. (Never seen this bit though, just been told about it.
It is important that there are not any other leaks. The throttle control cable is insulated from the engine. I believe the rubber bushing on the throttle bolt stops the current going up the engine control cable and back down the gear lever cable which does not appear to be insulated.
Best explantion I have seen on this subject. Thanks
That’s good advice from Serendipity about changing the prop shaft seals, I had mine done on my 2002 Bav 36, and had the whole job done by the boatyard at the Marina where the boat was kept. The shaft seals were shot and had leaked water into the sail drive, but that is now cured. As for the hull seal, like everyone else the old seal from my boat once cleaned up looked as good as new.
Has anyone had leaking problems with the sail drive diaphragm – in any Bavaria yacht? Has anyone replaced the diaphragm as a result of the 7y (8?) suggested replacement interval and if so, found that the diaphragm was in poor condition?
I have yet to hear of any problems with the diaphragm, regardless of model or age of the vessel.
Any feedback would be greatly appreciated because our B36 is 11y old with the original diaphragm!!!! Should I or shouldn’t I?Good morning Bob
It’s very much your call!! As you will see from my post above I had my B32 diaphragm replaced a couple of years ago and there was absolutely nothing wrong with it. Just about everyone I know who has had the job done has reported the same outcome. The worry is that, in the apparently unlikely event of a serious failure what would be your insurance company’s response if they found out that you hadn’t replaced the wretched piece of rubber when Volvo say you should!
Best regards
Ian Culley B32 Another Fantasy
Hi guys,
Reading this with interest. I am halfway through replacing the diaphragms on my boat at the moment. Admittedly it is a Yanmar engine and saildrive with their double diaphragm arrangement. I undertook this project as we found that one of the diaphragm clamps was missing – so someone has been in there at some point. No record of the work ever having been done so on a 1999 boat bit the bullet and got stuck in. Saildrive currently in pieces in the garage and just about to rebuild and re-attach to engine. Waiting for the prop shaft to come back as it had to go off to engineers to be re-chromed and then ground back down to remove oil-seal wear grooves. Replacing all associated seals diaphragms etc etc. Myself and wife got it out ourselves and will put it back in ourselves, bit of a wiggle but it will fit!!
Of course, relevant to the thread….the diaphragms that came off the leg looked like the new ones, no sign of wear or age. I keep telling myself that at least I can sleep more soundly. The Yanmar parts have no date marking, or markings at all, but we keep full records of work done and parts replaced. Should all be back together in week or so when the weather allows.Derek Cowan
B38, Alcyone of ArgyllI bought my bav37 may 2014 and the diaphragm came up on the survey because there was no record of it being replaced from new. A quick check with Volvo confirmed it was passed recommended life and I felt this could be an insurance problem because of the survey note. I got Signature Marine to do the work for me and they did a superb job along with an engine service.
There are many jobs I will tackle on the boat but not this one so respect to those that do and will, for me the cost justified the importance of the work, the timeframe I needed it completed in, the peace of mind for me that it had been done properly, the Warranty and the fact they were present for the relaunch to make sure all was fine – which it was.
I am not convinced that these need replacing with the frequency Volvo recommend but whilst they do it is hard to ignore. I now have a few years with one important thing less to think about.
I am not sure how I would feel if I was looking at a used boat that had this recently replaced by an owner, you may want to consider this if you’re thinking of selling in the near future.Interesting on reading that you had it done professionally and many people will choose this course of action commensurate with their confidence and ability to do such work themselves. certainly our yard raised eyebrows when I suggested we would tackle this job ourselves. Looking over the internet it appears that many owners tackle such jobs themselves. However, you raise an interesting point about whether this might be an issue for anyone purchasing a boat where such jobs are done by the previous owner…I have to respond, in that we decided to do the work as the previous owner DID have all of his work done by yards/professionals. When I was checking over the engine I discovered one of the vital diaphragm clamps was missing, they can’t fall off as the clamp is continuous, it had not been fitted at some point. When the prop shaft was removed prior to lifting out the leg, we found that the oil drain plug o-ring was missing, the last professional in there had not refitted one. The shaft oil seals had been moved along the shaft therefore doubling the wear on the prop shaft so that a speedi-seal for £20 could not be used but a £300 re-chrome and grind is underway. The “super-lock” washers holding the shaft parts in place – all missing. This obviously does not apply to all professionals….but after doing the work yourself, you KNOW that all the right bits are there in the right order and I do sleep soundly at night.
All skin fittings and seacocks also off and being replaced with DZR ones, this also aids a good nights sleep!!
By the way…we found the 3/4″ fittings all screwed off eventually, the 1.5″ fittings came off easily using a Dremel to cut the flange off, about 5 mins a fitting.Best Regards
Alcyone of ArgyllWhen you say used a Dremel on the 1.5 flange, which flange do you mean, the ext or the interior? Can you describe the no of cuts made as the dremel is quite a precision cut.
@Mistral wrote:
I bought my bav37 may 2014 and the diaphragm came up on the survey because there was no record of it being replaced from new. A quick check with Volvo confirmed it was passed recommended life and I felt this could be an insurance problem because of the survey note. I got Signature Marine to do the work for me and they did a superb job along with an engine service.
There are many jobs I will tackle on the boat but not this one so respect to those that do and will, for me the cost justified the importance of the work, the timeframe I needed it completed in, the peace of mind for me that it had been done properly, the Warranty and the fact they were present for the relaunch to make sure all was fine – which it was.
I am not convinced that these need replacing with the frequency Volvo recommend but whilst they do it is hard to ignore. I now have a few years with one important thing less to think about.
I am not sure how I would feel if I was looking at a used boat that had this recently replaced by an owner, you may want to consider this if you’re thinking of selling in the near future.Curious what was the condition of the diaphragm when it was replaced and how old was it? Thanks.
Regarding the Dremel…it was my three 1.5″ fittings that would not budge from the inside…could not get any of the seacocks off the skin fitting either. Did not want to use an angle grinder as I knew what would happen. Read about this option online, so, using the Dremel with the metal cutting disc from the outside of the boat, start cutting the inside of the skin fitting tube. At first the disc which is 38mm will not go up into the tube, so I just started cutting into the edge of the hole to wear the disc down a little but once it wears down a bit it will go up, just start the cutting inside where you estimate the hull level is so that you are only cutting the fitting tube and not the wider metal flange part. Just slowly cut into the tube working around the inside, once it gets through the metal you feel it “drop” long before it starts cutting GRP. This way you cut the outside flange off as a ring. The whole of the tube then just pushes up into the boat. Once you get over the fear with the first fitting and find that it is easy to to avoid any damage, the next two really did only take 5 minutes a piece. You can use the smaller coarse cutting discs but they wore down fast and I spent more time replacing them than actually doing the cutting.
Hope this helps.Derek
Alcyone of Argyll
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