My Replacement of the Volvo-Penta Seal on a 43DS
Apr 24, 2024 19:34:10 GMT
Post by seattledale on Apr 24, 2024 19:34:10 GMT
My Jeanneau 43DS is a 2005 model with a Yanmar 4JH3 50hp diesel, 35mm prop shaft, and a Gori 18” diameter 3-blade folding propeller. I purchased the boat in 2021. While I have had no problems with the seal in the three years I have been sailing the boat, it definitely appeared that the time to replace it had come. Particularly after I discovered that it requires greasing each year (news to me) and the manufacturer says it should be replaced every 5 years. Thus began my education as to how to properly treat this essential item. I called the previous owner and got a rather vague response – “Ahh, I can’t really tell you much….” when I asked about its history. So now I started to wonder if it had EVER been changed or serviced. But, it wasn’t leaking, yet. The Forum here was a wonderful source of information and I thank the members for providing great responses to my inquiries. I hauled out last week at a DIY boatyard. Here is the story of my trepidation going into this task, my depression during the task, and the glorious feeling of accomplishment upon completion of the task.
A few months ago I purchased a new Volvo-Penta seal. The original seal in my boat is stamped 828524, but this came up as Obsolete in my local distributor’s database. I was assured by two distributors and a couple of Forum members that if I have a 35mm shaft, the correct seal is part number 828526. I went ahead and ordered 828526 and it is indeed the correct seal for a 35mm shaft. Interestingly, here in the States it appears no matter who you order it from, the seal is direct shipped from a warehouse in Mississippi. The price is $228 and it comes complete with the seal, the clamp, the orange plastic guide used when sliding the seal down the shaft, and a tube of Volvo-Penta grease.
Once the boat was out of the water the work began. I had 5 days to remove the coupling at the transmission end of the shaft, remove the old seal, install the new seal, put the coupling back together. And I had to get two coats of bottom paint on the hull. By myself.
Separating the shaft coupling from the transmission flange was easy. There are four 8mm socket head bolts that were easily removed. From outside, I pulled back on the propeller to separate the coupling from the transmission flange. You need enough space to get a large 36mm deep socket into the forward end of the coupling to remove the M24 nut that is threaded onto the end of the shaft. You will also need a breaker bar on that socket because it is on TIGHT; “Red-face tight” as one Forum member described it. And you will need some method of preventing the shaft from turning while exerting a lot of pull on the breaker bar. The four 8mm bolts on the coupling are on a 100mm diameter bolt circle. I used a 12” (300mm) length of angle bar and drilled a couple of holes to pick up two of the holes in the coupling such that the angle bar contacted the hull to counter the torque. Surprisingly considering the horror stories I had heard about removing the M24 nut, it only took a few grunts of tugging before the nut started unthreading. My M24 nut is a Nylok type with a blue ring of nylon on the last four threads. It also appears they had used some red Locktite on the threads in front of the nylon (see photo). I understand that one must sometimes heat Locktite with a torch to remove the fastener but I’m glad I did not resort to a torch as that might have destroyed the plastic nylon.
Then the fun began. I had a couple of commercial wheel pullers but they take too much space to fit. And the prop shaft end had no center dimple to press against. Already having suspected the commercial pullers might not work, I had started to fab a DIY puller a month ago but then my friend handed me the perfect item from his scrap pile: a rear spindle from a 1972 BMW. This is a disk of about the same diameter as the coupling and has four 14mm holes on a 100mm bolt center that align perfectly with the shaft coupler’s holes. The center of the BMW spindle had a large spline opening where the axle shaft used to go. I covered this opening with two large thick washers. Now, using four 3” long 3/8” bolts I attached the spindle to the forward end of the shaft coupling using 3/8” nuts and washers. I screwed the M24 nut back on the end of the prop shaft inside the coupling, but just a few threads of engagement, enough to hold the nut in place but still quite a distance from contacting the bottom of the coupler bore. I then selected a random long socket from my tool kit that easily slid inside the M24 nut; this guaranteed that the socket would contact the end of the prop shaft in the center. I started evenly torquing the four bolts, thus compressing the spindle towards the coupler and pushing the socket into the shaft end. Well, I kept tightening those four bolts to the point where I got worried they’d snap; they were only normal strength Grade 5 bolts. This is a tapered shaft so if it moves just a fraction of a mm it will pop off. It didn’t. Incredibly frustrating. I tried multiple times with no success. Off to the hardware store and I bought four new 3/8” hardened Grade 8 bolts, Grade 8 nuts, Grade 8 washers. These are much stronger. Per the engineering tables, these strengthened 3/8” bolts can be torqued to over 40 ft-lbs. Using a torque wrench I slowly and evenly brought up the torque to close to 40 ft-lbs on the four 3/8” bolts. Still nothing. After a long telephone conversation with my mechanical engineering buddy, he said I needed to pour heat into the coupling, aiming at about 200degF (94degC). This coupling is fairly heavy and it would take a while; he figured about 15 minutes. I had been working on this for two days now and was getting somewhat depressed. But it was now or never. I hit the coupling body with the propane torch on high (after protecting the areas of hull near the flame. And 5 minutes later…BANG! The coupling released the shaft with quite the announcement! Once it cooled down I removed the puller (BMW spindle), reached in and unscrewed the M24 nut and gently lifted the coupling off the shaft. And that night was the first sound sleep I got in days.
Next, I removed the clamp and pulled the old seal off the stern tube and off the shaft. The shaft looked remarkably good where the seal had been; no serious scratches or grooves. I gently polished it with some 800grit paper. Then I examined the stern tube where the large end of the seal clamps to the boat. The specs for the 828526 seal state the stern tube is to be 54mm diameter. I measured and found Jeanneau had used a 50mm stern tube. Then I took a closer look at the original seal and found there was a thick rubber sleeve stuck inside the large end of the seal. I pulled it out, it seemed like it had been added when they assembled the boat. Hadn’t come across any mention of this rubber sleeve in the Forum postings. But it appeared in good shape. I slid it over the stern tube and measured again, now it was 54mm. Hmm. This is purely speculation on my part, but I am thinking Jeanneau originally planned on a 25mm propeller shaft but then changed to a 35mm shaft with the larger 50hp engine, and thus increased the outer diameter of the stern tube by adding the thick rubber sleeve. Anyhow, I greased up the new seal, installed the lip protector plastic guide inside the narrow end of the seal as per the Volvo-Penta instructions, and carefully slid the new seal down the shaft and over the rubber sleeved stern tube. The new clamp was installed and tightened over the stern tube.
The coupling with its key was carefully slid over the forward threaded end of the propeller shaft. The angle bar was bolted to two of the coupler holes and positioned to contact the hull so as to prevent rotation when torquing the M24 nut. Using the 36mm socket and breaker bar I tightened the M24 nut. I had made some calculations as to how much to torque this nut; I measured it as a 2mm thread pitch and made some assumptions as to the friction factor. For better or worse I came up with a torque of 197 Nm (145 ft lbs). This was beyond the range of my torque wrench so I ended up having to guess a bit with the breaker bar, but as the M24 nut is a Nylok type and I used a bit of Locktite 271 Red, I felt reasonably comfortable; it’s on tight. The one thing you never want to happen is to have that M24 nut unthread itself; it is what prevents the shaft from pulling free of the coupling. For peace of mind, I added a 35mm shaft anode to the propeller shaft on the outside of the boat located 7” (180mm) forward of the cutlass bearing strut, figuring that if the propeller shaft ever somehow pulled free of the coupling, the anode would hit the cutlass bearing before the shaft could pass through the Penta-Volvo seal and leave me with a 35mm diameter hole below the waterline. Wouldn’t that be exciting….
So that’s my story. I made my splash-in date, checked for leakage around the new seal (none), and motored back to my marina over the next two hours while constantly checking that seal. I’m an electrical engineer, not a mechanical genius so I was somewhat out of my comfort zone. But all’s well that ends well I guess. Sorry for the long post but maybe my experience and observations might be of some use for anyone in a similar situation. Oh, since I doubt most would be lucky enough to stumble across a 1972 BMW rear wheel spindle to use as a puller, you can easily fab one yourself with just a piece of heavy steel plate (say ¼” or 6mm thick) cut roughly the same diameter as the coupler flange diameter, with four equally spaced holes on a 100mm diameter to match up with the coupler’s four holes. Happy sailing.
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