Serious rattling sound from Bravo3, but was recently rebuilt

sdrevik

New Member
Jul 9, 2007
86
Knoxville, TN
Boat Info
1992 SR Sundancer 270DA
Engines
454/B3
Recently purchased 1992 Sundancer 7.4L B3 outdrive, previous owner had lower outdrive rebuilt recently (verified with mechanic), last fall I believe.

On our 4th outing, the trip out was smooth. I had noticed the fuel mixture has been rich lately (gas smell in exhaust). After powering down in a cove for about an hour, restarted and got the most awful rattling sound. Immediately checked prop- no fouling.

Made it back (10 min drive, didnt go to WOT), but rattling persisted (passengers were nervous). Doesn't do it at all in neutral. Max RPMs fall from 4100 to 3300 to 3500. Trim up/down doesn't matter.

Thoughts?
 
I should add...

.. freshwater use only & the mechanic (a Sea Ray expert) gave it a 3-hour inspection only a month ago. Engine temp and oil pressure fine.
 
I don't know what it could be but you need to get it checked out right away. I would not run the boat until you get it checked.
 
Oh yeah... mechanic is coming out Monday, but would like to ensure I have a good list of things to have him look at.

I just can't figure how it went from running smooth goint out to total about-to-pull-itself-apart rattling. Very odd.
 
Your driveshaft and u-joints spin all the time even when the outdrive is in neutral. Since you say it is quiet in neutral, then that pretty much eliminates everything except the internals of the outdrive. Do you have the noise in both forward and reverse?
 
Forward and reverse, yes. It's pretty clearly an outdrive issue (the question is what, how much, and how long...)
 
sdrevik said:
Forward and reverse, yes. It's pretty clearly an outdrive issue (the question is what, how much, and how long...)

Break
Out
Another
Thousand....

Sorry....after throwing $17,000 into engines and trans on my 310, i have become synical.....Its for sale if you know anyone.... :smt100
 
Sounds like your lower unit. Drain the oil in the outdrive. I bet it is full of metal and probably smells burnt. Whoever worked on the lower unit last probably made a mistake.
 
The result

Lube oil was fine, I check that every 2-3 outings.

Nope, apparently one of the gears or bearings just broke apart and little pieces of metal started flying around. I'll find out more about the previous rebuild when I meet with them tomorrow (see below).

Lower section is gone, that's the bad news. The good news is some other poor sap ran his boat over some rocks on his maiden voyage about 6 months and put an 18" hole in his hull, but didn't scratch his outdrive. Just happens to have the same gear ratio (220), and no boat to put it in. So I get an outdrive with only 6 hours on it for half price ($4500 + install). Should be back in the water this weekend, in time for Labor Day.

A rebuild, I assume, just replaces gaskets, seals, and probably some bearings, but I assume a major component just lost a tooth or something. I am curious, though.
 
The result

Lube oil was fine, I check that every 2-3 outings.

Nope, apparently one of the gears or bearings just broke apart and little pieces of metal started flying around. I'll find out more about the previous rebuild when I meet with them tomorrow (see below).

Lower section is gone, that's the bad news. The good news is some other poor sap ran his boat over some rocks on his maiden voyage about 6 months and put an 18" hole in his hull, but didn't scratch his outdrive. Just happens to have the same gear ratio (220), and no boat to put it in. So I get an outdrive with only 6 hours on it for half price ($4500 + install). Should be back in the water this weekend, in time for Labor Day.

A rebuild, I assume, just replaces gaskets, seals, and probably some bearings, but I assume a major component just lost a tooth or something. I am curious, though.
 
Bravo 3 Postmortem

So here's the damage:
Dsc001.jpg


Lesson learned:
There is no such thing as a rebuilt Bravo 3. The tolerances are too tight, even a Mercruiser trained technician says he couldn't put one back together and have it work properly. There are only remanufactured and new.

Learning this lesson: $4500 + labor

Having your boat back in the water by Labor Day: priceless.

:smt021
 

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