|Topic Review (Newest First)|
|12-29-2008 07:30 PM|
I'd go with cutlass bearing. Your repower put in a more powerful engine with more torque, from the prop / keel picture the rest is original to the old system.
Simplest solution usually works, check what changed and of those things that changed which can cause the symptoms.
If it made noise in neutral it would be the motor/belts etc..if it was the tranny the tranny would be making the noise, shredding and being obvious (screwed by now and unable to shift perhaps). Simple way to check is to take a sample with the dip stick, wipe it on a clean white cloth and look hard for metal bits.
Torque shifting friction to one side of the cutlass bearing; maybe.
|12-29-2008 05:29 PM|
Is there anyway to verify that the prop is properly seated and mounted to the shaft? Perhaps under loads a misalignment results in uneven loading of the shaft? (maybe you've already done this...)
Barring that, I come back to the tranny because problems they are something you can hear from the cockpit. Gear Oil Sample?
|12-29-2008 04:18 PM|
Originally Posted by timebandit View Post
I did notice a little gear box oil getting past the seal on the dip stick and dripping down the side when at high RPMs. This is why I think there may be too much oil in the gear box.
|12-29-2008 04:16 PM|
Originally Posted by jr438234606 View Post
Shaft alignment is another story. It could be that. Was shaft alignment checked after the boat was splashed, following the re-powering?
Originally Posted by jr438234606 View Post
|12-29-2008 04:03 PM|
|timebandit||First thing I would check is to be sure the mount bolts are still tight.|
|12-29-2008 03:59 PM|
The sound is not sustained. It only makes the sound when the engine is thrown into a heavy sudden load. For example, when coasting forward, and then suddenly throwing the engine into reverse at cruising RPMs. In this case, once the boat slows, and gradually starts moving backwards, the sound stops.
The way I discovered this was when I use reverse to slow the boat--like when coming into dock. I went and checked things out on my lunch break. it appears that I may have a little too much gear oil in the gear box. I'm going to verify this, but I wouldn't think this would cause the sound.
|12-29-2008 02:57 PM|
Well, it stands to reason you'll get the most torque when the motor is in gear, so I'll stick with my suspicion of the motor mounts until you do your visual inspection and find out other wise. To be honest, though, if that's not it, I'm not sure what would cause the sound.
Another thought - Is the sound sustained when your revs are up or does it occur only when you power up. If it's sustained, I would look at the coupling, stuffing box and cutless bearing. If it occurs only at the moment you rev and then is mostly quiet, I would go back to looking hard at the mounts.
|12-29-2008 02:49 PM|
Thanks for that. Here is some additional info:
Engine is new.
It's more like a scraping sound. It's not a belt. I figure it must be the shaft.
It only happens when motor is under strain, in gear, not just reved up in nuetral.
Engine was perfectly aligned at install.
Engine beds are original, but with slight modification aft.
I have not done visual inspection, but plan to today.
Here are some thoughts i had:
Torque is shifting engine, shaft is eating into cutlass bearing.
Bearings in gear box are bad.
Shaft is bent slightly, and only gives a problem under heavy load.
Prop is cavitating.
|12-29-2008 02:44 PM|
Originally Posted by bubb2 View Post
If Northshore Marine did the work, then good luck!
|12-29-2008 02:42 PM|
You say it's a screeching/scraping sound though - that's a little confusing to me which is why I suggested earlier if you could identify the region it's coming from. That may make an "internet diagnosis" easier.
To specifically answer your questions above:
If the engine is improperly mounted, it will temporarily misalign. If this was an older engine, I would suspect the rubber component of the engine mounts were worn. The motor's torque will cause it to jump when revved. This is easy to check. Just watch the motor as someone revs the motor up. If there is an issue, you'll see it lurch noticeably.
If that is what's happening, then yes, you are at risk of damaging the cutless bearing, as well as the stuffing box and the coupling.
It looks like you modified the engine bed to accommodate the new motor. When was this done? At the install or after some period of use. How have you measured the alignment?
(I've said this before, but I'll say it again now - gorgeous boat.)
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