I recently had a problem with my 356 prop shaft & keyway & had to be towed in. Marina maintenance reported that the seal (I had a dripless stuffing box put in before the boat was initially commissioned 3 years ago) failed and caused the key to rust out and fail. The boatyard felt that the key was made of low grade material. Anyway, they had to replace the seal, shaft (which got chewed up when they key failed), keyway, fittings, shaft realigned, etc to the tune of $2,300. I called Hunter who said sorry but the Hunter dealer had replaced factory seal so they assume no responsibility. They have never heard of a key failing. Hunter dealer is undecided if they need to help with this bill as of yet. I need to add that I had a knocking sound when I was on about a 15-18 degree tilt before problem happened regardless if I was sailing or motorsailing. Still is happening with new shaft & realignment. Would appreciate any comments/advice.
Shaft/keyway
- Thread starter Capthunter356
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Strange!
The key rusted??? First, that key is a ways from the seal. And, second, it should have been covered by the flange. I can't figure out how that key would rust under the flange. Third, the shaft is also held by a set screw. Even if there wasn't a key in there, there should have been obvious indicators before the shaft came out of the coupling. There is an 'O' ring on the shaft seal bearing housing that should have prevented any water from migrating up the shaft. When a shaft seal leaks, it is from the bellows to seal bearing normally. That would throw water away from the shaft. Anyway, maybe others here would have a better idea than me. If it were my call, I would guess improper assembly to start with. As for the rattling you describe, it may be that the shaft is not centered in the log. I'd have someone look at it that is not associated with the yard. One other thing, when the boat has been out of the water, the seal needs to be 'burped' after launching to evacuate any air so that the seal is lubricated. If your yard failed to do that, you could have had a heat-related seal failure. Having said that, I still can't figure out how that would have had anything to do with the shaft, key et al. You do know you may have an insurance claim, right? The key and seal will probably not be covered, but the rest of the repair may. Good luck, Rick D.
The key rusted??? First, that key is a ways from the seal. And, second, it should have been covered by the flange. I can't figure out how that key would rust under the flange. Third, the shaft is also held by a set screw. Even if there wasn't a key in there, there should have been obvious indicators before the shaft came out of the coupling. There is an 'O' ring on the shaft seal bearing housing that should have prevented any water from migrating up the shaft. When a shaft seal leaks, it is from the bellows to seal bearing normally. That would throw water away from the shaft. Anyway, maybe others here would have a better idea than me. If it were my call, I would guess improper assembly to start with. As for the rattling you describe, it may be that the shaft is not centered in the log. I'd have someone look at it that is not associated with the yard. One other thing, when the boat has been out of the water, the seal needs to be 'burped' after launching to evacuate any air so that the seal is lubricated. If your yard failed to do that, you could have had a heat-related seal failure. Having said that, I still can't figure out how that would have had anything to do with the shaft, key et al. You do know you may have an insurance claim, right? The key and seal will probably not be covered, but the rest of the repair may. Good luck, Rick D.
Does not make sense
I have the same setup on my 356 and will do a quick check this weekend. I tend to agree with everything Rick said. If the seal failed or was leaking you should have seen water in the bilge. Any signs of water leakage from the seal area to the bilge?
I have the same setup on my 356 and will do a quick check this weekend. I tend to agree with everything Rick said. If the seal failed or was leaking you should have seen water in the bilge. Any signs of water leakage from the seal area to the bilge?
Maintenance?
I can't quite picture this problem happening quickly. In other words, typical inspections and normal boat maintenance should have picked up a condition that had to have happened over time. My key is bronze in a bronze shaft with a steel flange; set screw turned hard into the shaft and 'tied' with monel wire. If there were no set screw and things loosened up, wouldn't the shaft try to back out of the boat every time you shifted into reverse? Could that have happened under sail if the set screw were loose or missing? Over three years, Someone needed to be looking a this area of the boat once in a while to 'burp' the bellows; to replace the transmission oil, or any number of normal maintenance items.
I can't quite picture this problem happening quickly. In other words, typical inspections and normal boat maintenance should have picked up a condition that had to have happened over time. My key is bronze in a bronze shaft with a steel flange; set screw turned hard into the shaft and 'tied' with monel wire. If there were no set screw and things loosened up, wouldn't the shaft try to back out of the boat every time you shifted into reverse? Could that have happened under sail if the set screw were loose or missing? Over three years, Someone needed to be looking a this area of the boat once in a while to 'burp' the bellows; to replace the transmission oil, or any number of normal maintenance items.
Keyway woes
What type of prop do you have? Do you put the shaft in reverse when sailing to stop the shaft from turning? The Key should not '"rust" it is bronze, or should have been. I did have a key work lose and vibrate out once, but the setscrews held and I replaced the key with one slightly oversized, aligned the engine, and had no further problems. Keyways working lose are most likely caused by vibrations induced by poor alignment or a bent shaft. this is often accompanied by a leaky transmission seal and or a leaky packing seal. The vibrations in the shaft slowly "hammer" the bronze key until it is loose and vibrates out of the keyway. Some keyways are cut so that the coupling covers the keyway enough so it can't come out, some are not. I think the yard has at least some liability, however best of luck proving it. I am not an advocate of the dripless seals because often their failure is catastrophic resulting inlarge amounts of water coming into the boat, however I'll acknowledge that many people swear by them. I'll stick with my flax packing. It has worked forever in the Coast Guard 41 that I used to drive, and it has worked in every sailboat I've owned (4 with inboard engines)without failure.
What type of prop do you have? Do you put the shaft in reverse when sailing to stop the shaft from turning? The Key should not '"rust" it is bronze, or should have been. I did have a key work lose and vibrate out once, but the setscrews held and I replaced the key with one slightly oversized, aligned the engine, and had no further problems. Keyways working lose are most likely caused by vibrations induced by poor alignment or a bent shaft. this is often accompanied by a leaky transmission seal and or a leaky packing seal. The vibrations in the shaft slowly "hammer" the bronze key until it is loose and vibrates out of the keyway. Some keyways are cut so that the coupling covers the keyway enough so it can't come out, some are not. I think the yard has at least some liability, however best of luck proving it. I am not an advocate of the dripless seals because often their failure is catastrophic resulting inlarge amounts of water coming into the boat, however I'll acknowledge that many people swear by them. I'll stick with my flax packing. It has worked forever in the Coast Guard 41 that I used to drive, and it has worked in every sailboat I've owned (4 with inboard engines)without failure.
Leaking Shaft Seal
I don't see how the shaft seal could leak on the keyway. My shaft seal after ten years started to spit a bit but the water goes to the side, not forward. I would say there is something fishy about the entire initial installation. Too late now but you might have been better off with a second opinion. Is it possible that you kept the old parts?
I don't see how the shaft seal could leak on the keyway. My shaft seal after ten years started to spit a bit but the water goes to the side, not forward. I would say there is something fishy about the entire initial installation. Too late now but you might have been better off with a second opinion. Is it possible that you kept the old parts?
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