Oh NO: Drop the Transmission!

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Well, not really the trans, but the “output coupler” that bolts onto the trans, that’s what we dropped! And yes, it dropped off in one of the most remote (so it seemed to us) places in Maine, Winter Harbor on the east side of Vinalhaven. Even though we check our engine nearly every hour when running, I can see no real way I could have caught this mechanical breakdown before it happened. Yes, I did have two very slight indications a few days prior. One clue was a dripping stuffing box that needed tightening and the second was a few drops of transmission fluid, but other than that, all seemed normal in the engine room.

Then while anchoring in Winter Harbor, after running the Fox Island Thorofare in pea soup fox, we heard a loud CLUNK when we dropped the shifter into idle reverse! I heard this from the bow, and Radeen heard this from the helm. She immediately returned to neutral, and I walked back from the bow and said…”What the heck was that?!”…we thought we picked up another lobsta pot and wrapped the prop. We could not see any floats, so we went back to idle reverse, then idle forward, and that’s when we discovered we had no prop wash. WHAT? Did the prop fall off? We had no propeller, we thought. Down to the engine room for an inspection, and that’s when I saw the transmission’s output coupler had dropped off (pulled off) the back of the transmission! This is something you do not want to see anywhere, much less in a remote anchorage in Maine.

Back to the bow, to continue with the anchoring, and lucky for us, we were in a safe place, with 25 feet of water and plenty of swinging room. Now it was time to inspect this breakdown and figure out what to do. First I took photos to document it and to send to Norm Pierce for advice. Then with close study and a review of the Yanmar service manual, it became obvious that the output coupler has a nut that bolts it onto the back of the transmission. So, an easy fix, separate the drive shaft (oh yea, real easy), find the nut between these plates, and bolt it back together. So that’s what we did.

Of course it took from 1600hrs to 2000hrs to separate the 4 drive shaft nuts and bolts as they were nearly frozen onto the threads. I used PB blaster and took it easy backing the nuts and tapping on them and re-treading them being careful NOT to shear one of these bolts holding the drive shaft to the coupler. By 2000hrs I had it all apart, and found the coupler nut in what appeared to be near perfect condition except for a major dent in the outer threads. This dent I assumed happened when the nut fell off and it seemed this dent was preventing me from spinning the nut on in what I thought was the correct direction. I tried to tap the dent out and I tried to open the dent to free the threads, but nothing worked. I did discover that the nut would thread on in what I thought was the opposite way, and that became the only way I could re-assemble this coupler.

So, the plan was set, we would re-assemble this nut, in a reverse direction, hoping that it would get us back to Boothbay where we could take care of a proper repair. At 0600hrs the next morning, we re-assembled the transmissions output coupler and used a pair of 90 degree bent needle nose pliers to tighten it the best we could. Of course I was working in tight conditions and standing on my head, but we were able to tap on the bolts notches and tighten the nut a bit. Our plan was to run in forward only, as reverse would be pulling on the nut and possibly loosen it again. Who needs reverse anyway?! (Note, this is right handed nut, normal threads with a right handed prop. So a quick change from forward into reverse could loosen the nut.)

Back towards Boothbay we headed, with stops in North Haven and then Rockland, and then we made Boothbay in time for the Maine Island Packet Rendezvous. Once at Boothbay, we were working with Boothbay Region Boat Yard. The recommended Yanmar service for this issue is to pull the transmission and send it back for a re-build where the output coupler would be torqued to the proper loads. This was a shock to us, and we would need to spend a week+ in the yard plus $1500 for a re-build and yard labor. We decided to go with our own temporary repair after I found out that I HAD replaced the nut the correct way and that the dent was deliberately made after it is installed. It’s called “calking the nut”, or whacking a dent into the threads into the shaft to prevent it from spinning off. (Yea right, you see how well it worked!)

With the encouragement of eternally optimistic Bob Drake, IP380 Drake’s Passage, we departed Boothbay together, with his offer of a tow in mind. After new transmission fluid and several runs out to the ocean and back from Boothbay, we felt confident to go for it, and take our chances and run for Rock Hall, MD, with this temporary fix! We had other Island Packet fleet members who offered to run with us and help us if we needed it. Thank you to Lyon’s Pride, Surprise, and CAVU, who on various legs, ran with us. We ran long motor runs: Boothbay to Rockport Mass 15hrs; Rockport to Cuttyhunk 15 hrs; Cuttyhunk to Block 7hrs; and Block to Cape May, NJ 30hrs. Lucky for us, the output coupler is still attached to the transmission with no leaks, so it looks like we will make it back to home port where we can properly take this apart and tighten it with the correct wrench and torque. In the words of Capt’n Ron, “If it’s gonna happen, it’s gonna happen out there!”

Lucky for us, we could fix it, and lucky for us, it ran all the way home!

Lessons Learned:

To check if your transmission output coupler is loose, do this:

  1. Watch the coupler while it is placed into forward and then a reveres, if it is loose, it will clunk aft when pulling in reverse.
  2. Use a pry bar and try to pry it aft then forward. If you can move it, it is loose

If it does come apart:

  1. Make sure you have tools to separate the coupler from the drive shaft
  2. Make sure you have PB blaster spray solvent to loosen the nuts
  3. Carry spare bronze shaft nuts and bolts if you break then

Tools Needed:

  1. Mirrors on telescoping rod
  2. 90 degree need nose pliers, also used to pull impellers, but was the main tool used to re-assemble and tighten
  3. Open ended wrenches and adjustable wrenches for the shaft coupler bolts
  4. 30” crow bar to loosen and tighten the stuffing box nuts

MUST HAVE: as advised by Norm Pierce of Pierce Yachts Boothbay Maine

  1. A zinc collar bolted onto the shaft 1 inch in front of the stuffing box, preventing you from “spitting a shaft” into your rudder and locking up your rudder! Norm Pierce made me put this on in 2006. Thank you, Norm!
  2. See Norm’s Photos here:
  1. Imagine if you are under sail, or if you hit reverse hard and pull the shaft off the transmission, it will jam into the rudder, this zinc collar prevents that. Norm installs one on every yacht he launches!

The warnings I had and how I could have caught this before it happened.

  1. The stuffing box started to leak with a steady drip way more than usual a few days before. This was after running all summer with that new Teflon stuffing that did not leak all summer. But now in the middle of Maine, it started to drip a lot. Hint: the shaft had moved back, but I did not catch it. I instead, I tighten the stuffing box to stop the leak.
  2. Three little drops of transmission fluid appeared on the engine room wall off the transmission. It spun up and flung onto the wall. I noted this in the log book 2 days prior. This was an indication of the coupler was loose off the seal. Caught that, but missed what it was saying.

Lucky for me, the prop shaft did not drop off in any of these tight channels with rocks all around that we had run through so many times. Overall, it was another great learning experience and now I have shared it with you, so go check you output coupler.

The output coupler nut, is notched and needs a special tool

Our “special tool” 90 degree needle nose pliers used to tighten

Output Coupler and the nut

Winter Harbor on Vinalhaven Maine, a beautiful place…
but a lonely place to make a repair! We appreciated IP380 Memphis Belle and IP420 Oro Negro nearby and checking in with us during that long evening!

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