For the past 10 years I have been trying to solve a problem on a 1972 glastron with a terrible knocking sound.
At first we thought it was the engine, so we pulled it for a rebuild, but the engine was fine. The engine sounds great on a engine stand.
I have swapped lower units, no change.
Years ago someone suggested replacing the motor mounts. Two days ago I pulled the engine installed new motor mount bushing on the rear of the engine and in the front motor mount assembly (have not yet re-installed the engine).
Looking at the rear transom plate, there is significant play in the holes that the rear engine mounting bolts go through. I'm wondering if anyone has had experience with this and if this might be the cause of the noise.
In the video you can see the play of the bolt in the holes.
Has anyone run into this issue?
Did you find a solution?
I have the new bushing installed, and am debating if I need to do anything about the play in the mounting holes.
Any advice would be appreciated.
After I install the engine and test the boat I will update this video with the results.
7/20/2020 Still have the same issue.
I don't hear the sound when the running out of the water, or the engine on a stand.
Tried two different lower units.
Seems like the sound is when the engine is under load.
I was thinking that the flywheel might be rubbing against the flywheel cover.... Nope.
The engine runs fine, I just have not been able to pinpoint the noise....
Note: I did not not do anything about the play in the mounting holes.... so it is possible that is still the issue....
7/25/2022 Have not had the boat in the water for two years (too many other boats). I will update the next time I put the boat in the water.
-andy
5 окт 2024
