U Joint Failure: How Ugly can it get? How to prevent?
 

Merc 575sci w/ bravo XZ on a 2005 29' fountain.
Lovely boat, delivers every time.... never had a problem like this in 5 years.

{i posted elsewhere on the forum, but thought I'd put it here too}

HOW DID THIS HAPPEN? Just gave out with time or what?

Heard a noise, put in neutral.... revved up, no noise, put in gear, cruised at 3000 rpm for 60 seconds then bang, noise, and no forward.....

Now when i start it, it bangs and clanks....... sounds like a broken U joint.... it's loud.


What do you think? I won't have my trailer and truck down here (NJ Shore) Until Thursday.... although I'm tempted to go home and get it now, so I know what happened.... It's on a pontoon boat lift and I'm not interested in working on it over the water.

Should I have it fixed by a u joint shop or just buy a new part? It's like $1000!!!! WTF!!!!

sure sound like a U joint. Be careful with leaving it in the water sometimes it can take out the bellows as well. Take a look around the inside where the shaft comes through the gimbal bearing and make sure no water is coming in. Another big cause of that also comes from running the boat with the drives trimmed up to high. If you trim way up because of shallow water or accidently fire the boat up while its still in trailer position that will tear them up pretty good as well.

It could be a U-joint, it could be the drive. Remember, the shaft is spinning all the way through to the upper if the drive is in neutral, forward, or reverse. Everything is bolted together pretty tightly, and a loud noise could be transferred from one place and heard another.

U-joints are robust, but this may be an issue caused by some improper usage at or over some point of time. Running with too much trim over time will completely overstress the U-joints. I also see folks all the time that start and run their motors with the drives trimmed all the way up either on the trailer or while in the water. You CANNOT do this with any Bravo setup.

You can't do anything with the drive on the boat. And you can't float the boat without the drive on it (without jerry rigging it). You may need to replaced bellows and or other parts as well, which you do not want to do while hanging on a lift over the water.

1) Get the boat off the pontoon lift which is not designed for your hull and can hurt the hull.
2) Get it on the trailer, and get the drive off the boat. You ought to be able to determine U-joint vs. drive in very short order.
3) Be happy if it IS the U-joint that came apart, that it didn't just rip the whole transom assembly apart and sink the boat, which has happened to quite a few.

I hope this did not happen to yours......

http://www.offshoreonly.com/forums/d...reak-like.html

Guys thanks so much. I suspected the u joint and I hope it's only that..... with no collateral damage.

I am guilty of fresh water flushing the boat about 10 times this summer with the drive lifted all the way up... that's the cause i'm sure.


Running at 5 trim out is what the guys are running on this forum and I guess that's not the cause.

holy cow. if this IS what happened what is the repair?

I had a failure like that & it took a piece out of the gimbal bearing housing. The bellows wouldn't seal up & I had to replace the transom assembly.

uhh. I'm sick. Couldn't have happened on sunday evening... had to happen on Friday morning.

There is a video posted on here somewhere of a guy starting a boat in the street or driveway, all happy and proud...

...drive trimmed all the way up. :D

Kudos to you for sharing info on flushing the boat with the drive up. These things happen. It's how we all learn.

Yeah well, I'm not too proud to admit a mistake.... I surely won't make it again.

Now about that checkbook :lolhit: