Uppers shredded... whats the cause?

[rbryn]

2003 260DA with 320 hours (160 of which were in the past year)

We were running at about 4000 rpms when there was a loud "thud" and then an awful noise from drive. a 3hr tow back to MarineMax revealed the gears in the upper drive completely shattered and the housing itself damaged beyond salvage. With the parts being $4000+ I'm looking at trying to figure out the "WHY did it happen" part.

We aren't Marine Mechanics and I try to do my own maitnenance when possible. Drive lube was good with plenty in the reseviour, there were no leading indicators or problems prior to the failure. Although we can't swear we didn't hit anything in the water, we were in 45' of water and there wasn't any scarring on the skeg or prop to indicate a hit (although my wife swears she heard something hit).

Other than "just failure" would there be any other reason for it to fail that I'm missing... I'de hate to think it will happen again in the next 300 or so hours.

 

[Dave S]

You might want to call the folks at http://www.sterndrives.com/ They sell new and remanufactured Mercury Sterndrives and might be able to give you some insight on what causes these types of failures.

It is also possible that Mercury may be willing to hlep out with a reduced price on the replacement drive since you don't have that many hours on it. It never hurts to call Mercury and see where that one goes.

Dave

 

[skolbe]

My dad had both Bravo III's fail on his 2002 Amberjack. They failed back to back years. He has all maintenance done by the dealer. I suspect it is heat that builds up and causes them to blow. Mercruiser and Sea Ray were not a lot of help. My dad had bought an extended warranty that paid to have rebuilt drives. He had the new style Bravo III's installed and paid the premiums. My friend sea trialed a 2005 - 400PC Formula that was a bank repo with 300 hours. Within 30 minutes a drive blew out.

 

[rbryn]

I suspect it is heat that builds up and causes them to blow. Mercruiser and Sea Ray were not a lot of help. ...... My friend sea trialed a 2005 - 400PC Formula that was a bank repo with 300 hours. Within 30 minutes a drive blew out.

That's about all I've gotten "it must have been heat build up"... doesn't give me a whole lot of confidence that I won't be back doing it again in 300hrs.

It's the equivelant of replacing the car's transmisison with only 15,000 miles on the odometer.

 

[rbryn]

It is also possible that Mercury may be willing to hlep out with a reduced price on the replacement drive since you don't have that many hours on it. It never hurts to call Mercury and see where that one goes.

Thanks... might give that a try on Monday.

 

[Dave S]

Take a look at the Drive Shower site mentioned above since there is a lot of good information there as well on the heat build up in Bravo 3s.

I had the Simrek Drive Shower on my previous 240SD which also had a Bravo 3. As far as I am concerned, this is the best Drive Shower available. The only reason I don't have one on my current drive is we have a lot of electrolysis corrosion in our Marina and with my boat being wet slipped I didn't want to jeopardize my extended warranty with Mercury by hanging more stainless on the drive. (They already replaced my lower unit once due to corrosion). But you can bet your bottom dollar that when the warranty expires I will be purchasing one for my current B3.

Dave

 

[BonBini]

If you want to analyze the failure you'll really have to look closely at things.

Bearings:
>Heat related your going to see discoloring of the bearings with burnt lube present.
>Lack of lube you'll see disintegrated bearings without any lube present.
>Over loading you'll see fretting of the rollers and races.

Gears:
>Impact damage you'll see a gear tooth with a very quick break, showing little to no beach marks.
>Slow gear tooth break from shock loading you'll see a series of beach marks at the point of failure starting small then cycling larger before sheering.
>Over loading you'll see fretting to the tooth face.
>Alighnment will show up in wear pattern

Hire a pro: Hire a tech to do it for you and go with there opinion.

DIY: Since it sounds like a complete drive is in order. Perhaps you can tear the old one apart on your garage floor, lay it all out and figure out where the fire started, and then the root cause.

I sincerely hope all that was of some help to you and not just some Failure Analysis rambling. Sorry about your luck this early in the season.

 

[Fun Times]

I'm not sure if this guy still has them or not, But it could be worth a call.
I have a pair of Bravo III with props, 2.2 gear ratio and 24 pitch props, $2500 ea, or $4400 pair. Wayne 702-370-8635

http://www.riverdavesplace.com/forums/showthread.php?t=29175

 

[rbryn]

If you want to analyze the failure you'll really have to look closely at things.

Bearings:
>Heat related your going to see discoloring of the bearings with burnt lube present.
>Lack of lube you'll see disintegrated bearings without any lube present.
>Over loading you'll see fretting of the rollers and races.

Gears:
>Impact damage you'll see a gear tooth with a very quick break, showing little to no beach marks.
>Slow gear tooth break from shock loading you'll see a series of beach marks at the point of failure starting small then cycling larger before sheering.
>Over loading you'll see fretting to the tooth face.
>Alighnment will show up in wear pattern

........................

Hire a pro: Hire a tech to do it for you and go with there opinion.

Thanks! that's exactly what I was looking for!

I strongly believe in letting the pro's do what they know best. This is beyond my capabilities at present and I'm only inquiring in order to prevent a repeat later down the road. I'm pretty good at tearing things apart, but putting them back together again is not as much fun

This should give me enough info to take the old housing, pull it apart and determine what and if the contributing factors are.

 

[rbryn]

Heat can definitely be an issue. Once you are back in the water, you might look at installling a drive shower to help keep it cool.

Something like this may work....http://www.driveshowers.com/

Never seen one of these on a SeaRay in our area, but I'll definitly be doing some more investigation if it turns out to be 100% heat related... reading the site - alot of it seems to be plain common sense. I can definitly see how one would be beneficial.