Video Link - Still Trying to Diagnose Squeal in Forward

[Therapy]

Good to hear you found it.

Best of luck.

[Chief Engineer]

I followed this...glad you found the problem

[Northeaster]

Update - I am not a happy camper!

After taking the prop shaft out in the fall / winter, and finding scoring marks where misalignment had caused the shaft to rub against the side of the stern tube and the edge / side of the bronze suffing box, I figured I had found the trouble. I centered the shaft near the center of the stern tube (What do I mean "near" the center? Well, the stern tube is not perfectly aligned with the propeller shaft and strut, so I did my best to center the shaft, so it would not rub again.)
Then, I moved and adjusted my engine mounts so the engine was aligned with the prop shaft.

The boat just went in the water, and I ran the engine for a while today, tied to the dock. Same as last year - Squeals in forward and not in reverse.
I am back to thinking that it must be a bearing or something in the transmission. Other than the squealing noise, it runs fine, and we put up with the noise for the last 2 years. Looks like I will put up with it again this year, and likely pull the trannie next year. Had it apart a couple of years ago, to lap the drive cones, as it had not been going into gear well. Works A1 now, other than the squealing noise.

We only motor for 5-10 minutes in and out of the marina, and on the occasional, infrequent low wind days, so I am not going to pull the transmission now that we are getting into prime sailing season!.

[Northeaster]

Hi Folks,
Decided to continue this thread, as.... well.. the saga continues.

Enjoyed great summer - lots of sailing, and some motoring, still putting up with the squeal sound in fwd (video link of noise on page 1)

Now that boat is stored indoors again for the winter, I have just removed the transmission and had a quick look.
- The damper plate looks quite uneven / warped a bit, and a couple of the springs have some flat spots on the sides of them (as if they have been rubbing on something (likely flywheel I guess). Will price a new damper disk, complete with springs.
- The propeller shaft turned easily, while gearbox was still attached (in neutral) and I don't think it is rubbing on the stern tube or stuffing box.
- There seems to be quite a bit of play / clearance in the input shaft, as I am able to pull / push it in and out. there is also some side to side play.
- there is a very slight amount of play in the output shaft. (in and out)

When I removed the bell housing / mounting flange, I did not see any shims behind the bearing races on the output shaft, and on the input shaft there is what looks like a washer with a slot in it - Are shims a full circle, or do they have slots in them, like 1/4 - 3/8" wide??

I have the manual, but I am unclear as to how I am supposed to measure the clearances. It shows what the clearances should be, but how do you go about measuring the distance between the races, when one race is in the end of the gearcase, and the other is in the |(removed) mounting flange?? Do I need to put the mounting flange back on 1st?
If someone could explain how measure, in simple laymans terms, I would really appreciate it.

[Northeaster]

Posting a couple of pics of the old damper plate / disk. If you look closely, you can see some wear marks on a couple of the springs, where they were obviously rubbing on something. I think that "something" would be the flywheel. Not sure if this is the noise culprit, but I think that the weakened springs (25 years old) may have caused more play between the inner and outer damper plate parts, and this may have caused some rubbing against the flywheel, as it turned. At 1500 - 3000 rpms, I am thinking that could have caused some noise.

Priced the damper plate at local Yanmar dealer (Halifax, Nova Scotia). Was ready for a hefty price, as I saw list prices of about $283 on -line at Torreson's, etc. But, was not prepared for the $580 local (robbery) quote. Luckily, found a new one on Ebay for $149, and $10 shipping.
May have to ship / pick it up in Maine, but am over that way every few months anyway.