Changing shaft seal on Bukh DV10LSME Saildrive

The rear shaft seal sits in a self contained housing that also holds the rear bearing. It's tendency is to corrode with time. The result of this corrosion is a leaking seal. The complete rear bearing housing no doubt needs to be replaced. You'll be able to confirm this once the prop and zinc have been removed for inspection. You'll need to find a way to remove the bolts even if you have to weld an allen key to them, then replace the bolts afterwards. Goodluck

Edited by Bill Layton - 09 March 2011 at 1:04pm

Yes the seal can be pulled and changed. However once you remove the prop you will see the real problem lies in the housing and not the seal. I have changed this part many times and the housing is always the problem. It just corrodes away and is unable to form a tight seal around the seal and hence the leaking. :)

Hi,

thanks for your help !

I am thinking of maybe not doing anything right now, but leaving it the way it is for now and tackling the repair next winter.
It is not leaking much oil, maybe one or two drops per week now as it stands on land.

But how high is the danger of water leaking in and how much water might get into the saildrive and could it be damaged by this when using it like it is for one season?

Do you have any hints on this?

Otherwise I would just try to change the seal now and change the bearing housing next winter.

Regards, Michael

Hi,

I had success removing the sealing ring from the outside. It came out easier than I expected. The bearing housing seems to be ok, no signs of corrosion.

Thanks for your help!

Regards,
Michael

I just ordered one last week from Crinmar Marine (http://www.crinmar.com/). Unfortunately they don't last that long here in the salt water, and they're not cheep (~$280).

Looks like I have a leak at the shaft seal.  I had water in my gear oil, so pulled the boat to check.  I drained and refilled, then wrapped a diaper around the sail drive and waited.  Although I was hoping that I would find a leak at the drain screw, what I found was an oil stained diaper around the zinc area, which seems to indicate the shaft seal is bad.  Fortunately, the boat came with a spare.  Now I have to put it on.  I have read everything here at site regarding replacement.  I have the DV8.  I see the ideas for removing screws...does anyone know what size the allen screws are?

Ron,
The allen wrenchis 6mm. Clean the allen head of the screw very well to be sure the wrench gets a good bite. It will be a bit tough to get the first crack, but it should yield. Be careful not to damage the screw head or your job will become more difficult.

You said that your boat came with a spare seal. Please confirm if you mean that it came with a spare seal (meaning just the rubber seal ring part), or did it come with a spare Rear Bearing and Seal Assembly. Crinmar never sold the seals separately and only sold the entire assembly which cost near $300 if I remember. The original rubber seal is unusual and is no longer available. It was a 30 x 17 x 9mm. What is unusual about it is that it is actually a double seal made so that one seal keeps the oil in and the other keeps the water out. The other response to your post suggests a 30 x 17 x 7mm. That won't do because it is a single seal. If you have a spare seal that is a double seal (note such a seal is configured like two seals placed back-to-back) then you can just change it. It can be done without removing the Rear Bearing and Seal Assembly but it is not easy to get it out. It is possible to pry it out with a screwdriver, then clean up the seal housing and replace with the replacement original seal (if you really, really have one....which I doubt).

Otherwise you must take the lower bit off the leg. Not really a problem.

1. Drain the oil.
2. On the port side of the lower leg you will find a flat head screw on the lower side going transversely across the lower part of the leg. That screw holds the bottom of the shifting linkage in place and acts as a pivot for it. Clean out all the marine crustacea, and remove the screw.
3. Remove the 6 allen screws and pop the bottom of the leg off.
4. When you remove the leg, the prop shaft together with gears, multiple spacers, etc, will also drop out. Don't let it fall out with gears rolling around on the dock, and most importantly loosing the sequence of the spacers. These spacers keep the shaft and its gears in perfect alignment with the main drive gear coming down from the motor. If you loose the assembly sequence of the spacers, you will never get the gears properly aligned you will have to follow a procedure that requires having the entire leg out of the boat, which requires removal of the engine. So, you need two people and you must very carefully take that bottom piece off, knowing and expecting the shaft to drop out, and making sure that someone is under it with two hands holding something like a towel waiting to cradle that shaft assembly when it drops. It may not drop.....it may sort of stay in place because of the sealant used in the assembly and it may sort of stick to the upper unit. Then when you turn your back, it will fall out and bits will go all over the place. No! No! No! If it sticks, someone must hold it with a towel, keeping everything in place, while the other person just taps down on the prop side of the shaft and knocks it loose.
5. Lay the shaft assembly somewhere safe preserving its original assembly. Keep it wrapped in the towel.
6. The Rear Seal and Bearing Assembly is trapped between the two parts of the unit. When you tap down on the prop side of the shaft, that assembly will come out with the shaft. That is the only bit you may remove from the assembly.
7. The outside of the Rear Bearing and Seal Assembly has a Stainless cir-clip (keeper) usually retaining a very thin stainless washer, which backs up, protects, and retains the rubber seal. Remove the keeper and the washer. Then place the assembly seal-side down on a piece of wood and knock the seal out from the opposite end using a drift or small screw driver and a hammer. It has also been put in the seal housing using a sealant so will be a little tough.
8. Clean up the seal housing, and then use the required sealant to put in place the replacement seal (which I don't really think you have), and put the washer back on together with the keeper.
9. With the above done you may now reassemble everything. Use the DV8/10 workshop manual as your guide, but it is relatively simple. Your assistant will have to hold the shaft assembly up into its new position with the Rear Bearing and Seal Assembly on the shaft. The Rear Bearing and Seal Assembly has a little slit on the side and that must align with a small tit in the leg housing. This prevents the assembly from spinning with the shaft. Also, on the fore end of the shaft assembly, there is one spacer with a tab on it. That aligns it a special way with the housing also to prevent it spinning. It is easy to pay attention to it when you take the shaft out and then make sure it goes back the same way, otherwise refer to the shop manual. Easier to track it on disassembly though if you are a first timer.
10. On reassembly I use a silicone sealant from Permatex, though that is not the recommended sealant. In any case, I use that, then tighten the screws to just snug, wait for the silicone to set, then torque the screws down.
11. Your next job is to re-align the bottom of the linkage system with the screw hole so that you can replace the pivot screw with the flat head. Use a long screw driver that will fit into the screw hold, or a rod, drift, etc. to help align the hole. Your partner may have to be in the boat gently moving the shift lever around to align the linkage with the hole in the casing. When it is aligned and the rod will go through retract the rod and replace the pivot screw.

NEW CHAPTER:

Now lets say that you don't have the right replacement seal. If you have the entire new Rear Seal and Bearing Assembly then simply replace the old one with the new. But lets assume you have a seal......probably not a double seal, but the closest size someone could find such as a single 30 x 17 x 7mm. Don't use that. Instead, here is what to do:

1. You are going to buy two seals that are 30 x 17 x 5mm. When you place these back-to-back they will be a total of 10mm thick which when placed into the bearing assembly will not give you enough room to replace the retaining washer and keeper. The original is 9mm. We are going to have to use a lathe to deepen the bore on the Rear Bearing and Seal Assembly by 1mm, or even a bit more, say 1.2mm. There is plenty of meat on the part, so no problem. This will allow the two new seals to be put in place and allow room for the retaining washer and keeper (cir-clip). Literally this is a 5 minute job on a lathe, so if you have one, or have a friend that owns a lathe, bring the beer and get it done. Other than that, take it to any shop with a lathe and they can do it while you wait. It is a very small cut.
2. On re-assembly, place the two seals in the assembly back-to-back with the open sides of the seal such that one faces fore to retain oil, and the other faces aft to keep the water out. Again I use the red silicone sealant from Permatex, but you can use the same or the equivalent of whatever the workshop manual suggests. You just don't want it to leak.

The two seals will cost about $4.00 each. A new assembly will be near $300, so it is worth doing.

Good luck with the project. When you are done, you will know more about your boat!

Thank you Fletch and Dick.  That info will be great to work with.

Edited by Ron Waterson - 16 January 2016 at 4:52pm

Awesome.  Thanks for taking the time to explain.

John,