Update: I've finally been down and checked the alignment.
First step was to spin the shaft. There was some crunching that sounded like mussel shells, then it spun freely.
Then I unbolted the coupling and tried to decide where the center point should be. Nigel Calder says you can approximate it by flexing the shaft around and finding the limits and then choosing the center of that.
With a Hurth
v-drive, I can only flex the shaft so far before it hits the inside of the transmission
output ring flange. It hits the flange before the shaft log in all directions and "feels" centered, but it's hard to say for sure (note, I have a PSS, so it's flexing all the way from the cutlass bearing).
I had trouble judging the alignment. It seemed to be a bit off, but when I spun the flanges it would be good. I was worried that I had a misaligned coupling or output flange, but then noticed there was a lot of gunk on the output flange. Once I cleaned it up, the alignment was excellent. I'm not sure if this would have been a problem once bolted on hard, but I'm glad I cleaned it up.
This is getting long-winded, but I'm not sure I'm closer to a solution. I feel like I have two possibilities:
1- There's some sort of problem with the cutlass bearing. This might be due to the inboard shaft end being in a slightly different place with the new installation
. The cutlass bearing is only 3 years old, but maybe it was worn one way and now is getting pushed in a different direction?
Honestly, I don't understand how this issue would mean that I'd get this very sudden onset of the very loud sound that would then go away for a while once I decreased rpm
for a few seconds.
2 - This is a new theory... The boat is horribly covered in sea life (coming out tomorrow for cleaning). I've read that a poorly cooled PSS can howl or squeal when it overheats. This is an issue on fast boats where a vacuum can be created and the cooling water
The problem started after a new engine
(maybe 20-30 hours after install), but this might be a coincidence. The boat is slowly choking with life and I could hear it around the shaft in the log. When I "burped" the seal, the water
that came in stank like the water in the head
flush hose after it's been sitting for a couple weeks.
What if there's so much life in there that cooling
water isn't circulating and the shaft starts to overheat?
Last time we came in to dock
, the howling was happening every minute or two. It's never been that bad before, but it always gets worse as a trip progresses. When I ran the engine in gear
at cruising rpm
for 15 minutes last night, I couldn't get it to go. Perhaps because the PSS seal hadn't heated up enough yet?
Is this plausible?
All that's left for me to do at this point is to inspect the cutlass bearing and prop over the weekend while I'm out of the water and hope for the best if they seem fine. I can't think of any other possibilities.