A break, I can't get.

M

mchad

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Over the winter in dropped a new Merc 383 mag MPI to replace a blown 350 carb'd in my '00 Crownline 242. Motor is fantastic. After my 20 hours or break-in, I'm planing at 300 rpm less then before (2" more prop pitch as well) and about 10mph more top end. Anyway, I recently noticed a tapping from the drive. Definitely coming from the drive, not the motor. Marina (merc dealers) looked at it, and said he thinks it's prob a bearing on its way. So, now I have a brand new motor, and a soon to fail Bravo 2. What to do. I could have them rebuild it, but I expect that's going to be a couple of grand. I could buy a brand new Bravo 2 for around 6k, and have a completely new "drivetrain".

My question is what are your thoughts on the reliability of a rebuild, vs. a brand new drive. $4k worth of piece of mind? Can a rebuild drive be considered just as reliable as a new one?

I'd rather not add to the $15k I've already dropped this year, but I also don't want to end up floating waiting for sea-tow with a drive in pieces...

Thanks
 
That might leave the oil looking glittery,did you drain and refill the drive? Disassembleb the drive or listened
 
We didn't pull or drain the drive. The tech did say there didn't appear to be anything in the oil reservoir (which I'm not sure there would be, metal doesn't float in oil I don't think) but he's been doing this for a long time, so I do trust him mostly.
 
Gotta drain some oil to see what's happening.

Can you give a better description and where the tapping is coming from? BII are tuff drives. Get a stethescope and listen yourself to locate the noise. Might be anything from flaps to U-joints. Tapping don't compute.

All that mechanic is doing is guessing. Sounds to me like he's setting you up for a new drive.
 
sound any different when you turn?

Listen to Charlie and use a hose or stethoscope to locate the sound.

Your "mechanic" will fix you with a new drive.
 
quote:
Originally posted by pdecat

sound any different when you turn?

Listen to Charlie and use a hose or stethoscope to locate the sound.

Your "mechanic" will fix you with a new drive.

Click to expand...


No difference. Same dead center bottom, or trimmed up, left or right. Yes, it needs further investigation. However once it's out and on land, I suspect I'll still need a decision to make, so still what's the opinion on rebuild reliability vs new, worth the triple investment?
?
 
Go with what you have now, and keep a Kicker for that emergency trip back home. I doubt you'll need it though.
If your not leaking water or oil and it's always had oil in it, never run dry, it's likely to run for a long long time yet.
 
I'd check the prop to see if you hit something. Only thing at the bottom is gears,shafts and bearings.

First, is it tapping only in gear or in neutral, too. Is the tapping regular. Is there a difference with RPM? Are you doing the checking in the water?

I don't understand tapping. You sure it ain't more like a clicking or ticking? I get a vague sense of tapping with a bent shaft...but those things are tuff. Maybe a cracked gear or tooth.

Either way, the bottom has to be removed. You can buy a lower case. How heavy is your boat? If it's under 6K you might be better off with a BIII lower.
 
quote:
Originally posted by jtybt15

I'd check the prop to see if you hit something. Only thing at the bottom is gears,shafts and bearings.

First, is it tapping only in gear or in neutral, too. Is the tapping regular. Is there a difference with RPM? Are you doing the checking in the water?

I don't understand tapping. You sure it ain't more like a clicking or ticking? I get a vague sense of tapping with a bent shaft...but those things are tuff. Maybe a cracked gear or tooth.

Either way, the bottom has to be removed. You can buy a lower case. How heavy is your boat? If it's under 6K you might be better off with a BIII lower.

Click to expand...


It could very well be considered a ticking. Happens in neutral (I haven't been able to listen yet when in gear) and varies with rpm. Prop is as new. I expect it is coming from the top of the drive, since if hear it on the swim platform, but like someone said, I'm just guessing too. Marina said a chipped tooth is a possibility as well. I'm thinking a replacement drive would get me back on the water fastest, as opposed to them spending a couple of weeks rebuilding. IDK...
 
quote:
Originally posted by jtybt15

I'd check the prop to see if you hit something. Only thing at the bottom is gears,shafts and bearings.

First, is it tapping only in gear or in neutral, too. Is the tapping regular. Is there a difference with RPM? Are you doing the checking in the water?

I don't understand tapping. You sure it ain't more like a clicking or ticking? I get a vague sense of tapping with a bent shaft...but those things are tuff. Maybe a cracked gear or tooth.

Either way, the bottom has to be removed. You can buy a lower case. How heavy is your boat? If it's under 6K you might be better off with a BIII lower.

Click to expand...


Oh, and I don't think I want to go with a III - add the cost of 2 new props, and the corrosion potential bothers me as well. I liked the B2 - when it was quiet!
 
They say a picture is worth a thousand words, so what's audio worth? I was thinking, I could talk about the noise all day, why not record it and let the experts hear for themselves...

http://youtu.be/CVYLz6RbY6Y

The sound does not change at any steering or trim angle.
 
Sounds like flaps to me. Doesn't sound like metal.

Does the intensity change with increased RPM?

Also a possibility the flaps broke off and are stuck in the drive. Again doesn't sound mechanical.

Oh, I swapped my alpha for a BII and love it.
What's your gear ratio and prop size/pitch.
 
quote:
Originally posted by jtybt15

Sounds like flaps to me. Doesn't sound like metal.

Does the intensity change with increased RPM?

Also a possibility the flaps broke off and are stuck in the drive. Again doesn't sound mechanical.

Oh, I swapped my alpha for a BII and love it.
What's your gear ratio and prop size/pitch.

Click to expand...


It's a 2.20 and a 21p prop.

I forgot to mention that it gets louder when hot. When first started, it's barely audible, but after hot, that's what you hear. At higher rpms I can't hear it as much, but I'm usually underway and there's too much background noise for my untrained ears.
 
Gotta get a stethescope or even a small rubber hose and locate the exact area of the sound.

I wish I had a 2.20. Mines a 2.0 . I have 17 1/4 X 23, 17 3/4 X 21 and a SS prop but forgot the size.

Your diameter would probably be 19 or 20 , maybe bigger with a 21 pitch. Those large BII props have a lot of stern lift so you should be able to trim out a touch more to raise the whole boat higher out of the water at speed. My boat better performance very similar to yours. What I like the best is better mileage since I can run 24 MPH at 3200. Dang boat weighs 7600 lbs for a 24' boat.
 
quote:
Originally posted by jtybt15

Gotta get a stethescope or even a small rubber hose and locate the exact area of the sound.

I wish I had a 2.20. Mines a 2.0 . I have 17 1/4 X 23, 17 3/4 X 21 and a SS prop but forgot the size.

Your diameter would probably be 19 or 20 , maybe bigger with a 21 pitch. Those large BII props have a lot of stern lift so you should be able to trim out a touch more to raise the whole boat higher out of the water at speed. My boat better performance very similar to yours. What I like the best is better mileage since I can run 24 MPH at 3200. Dang boat weighs 7600 lbs for a 24' boat.

Click to expand...


Its actually a 17 3/4 X 21 - QA1946R

Re: the noise. It's going to be a major pain. I expect I'll have to pull the boat out to do any real diagnostics, and the drive seems to need to be hot to get the noise to the level on the video I posted. How the hell do you get a drive hot out of the water?
 
At least you should be able to get up close and personal to locate the noise. I hope it's the flaps. You can pull the prop and check the prop shaft for trueness.
 
Went over today and started up. Tapping definitely increased in volume after a few minutes. Increased frequency (meaning tapped faster) proportionally with increased RPM. Same sound in fwd, neutral and reverse. However, interestingly, it seems that the noise is coming more from where I would expect the U joint to be, rather then the drive itself. I hung my head over the swim platform and I could hear it less then at an area directly over the transom. In fact pressing my ear against a surface above the transom let me hear it as if it was directly below it.

Sound is barely perceptible from the engine bay, and only at the far aft end of it. It was too windy to go out, so this was all done at the dock.

I would like to think it was the U joint, but I've never heard of u-joints making noise when straight - only in turns.
 
It's your flaps!! Easy fix unless they fell down. They're generally right at the top of the Y pipe.
 
Good news, sort of. They got the boat out yesterday and opened up the drive, dropped the fluid. He said the drive looks to be in very good shape, no unexpected shavings in the oil, no broken teeth on the gears visible from the top covers. They suspect the top cover bearing is the culprit. However they can't disassemble today due to staffing issues (read: someone is out sick) - so tomorrow we'll know for sure.

Fingers crossed...
 
Fixed. The main driveshaft bearing (just aft of the u-joint) was the culprit. While they were in there, they said I *should* replace the u-joint and gimbal bearing. So I did. Sounds like new. I'm happy. Until I get the bill that is...!
 
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