2006 5.0mpi stripped engine coupler

[ryan04]

I'm running a 2006 Tahoe with a mercruiser 5.0 mpi coupled to a bravo 1 outdrive.

I was on the water and a buddy got on the wakeboard. I punched it and it seemed like the boat was struggling for fuel. Started to lose speed so I just laid off the throttle. The following day I took some friends out crabbing and a half a mile from the dock it felt like we hit something (we most assuredly didn't) a crazy whining/zip noise then we lost forward gear, reverse etc but the boat continued to idle perfectly.

After I got the boat on the trailer I spun the prop by hand. I put it in fwd gear and could spin the prop both directions with ease by hand. Same with reverse and neutral.

When I got home I pulled the drive. I confirmed that by shifting the drive by hand on the bench that forward, neutral and reverse gears are all operating perfectly. Drive oil is nice and clean and free of metal shavings.

Next I looked through the gimbal bearing into the engine coupler. I couldn't really see anything so i put a magnet in there and it came out with a ball of shavings stuck to it haha. I managed to clean out the coupler and it appears to be stripped out. There are still teeth near the end of the shaft but 3/4 of the teeth are gone now.

I put the drive back on in fwd gear and shifted the throttle to reverse which pulls the cable into the boat. I then reinstalled the drive. This would confirm it's not a shift cable as the drive is in fwd gear and the cable isn't even close to hooking on. I then could spin the prop by hand once again.

Basically what i'm after here is when I pull the engine (which will be next to impossible as the engine bay is tiny and has next to no access haha) do you boys have any tips on what else to do while the engine is out of the boat?

I'm going to service the drive on the bench. On the boat i'm going to replace the lower shift cable as it's been getting sticky, gimbal bearing, all appropriate seals, spark plugs and the aforementioned blown engine coupler. Anything else?

Thanks Fellas!

 

[tpenfield]

Nice going, Ryan . . .

I've only pulled 1 engine (454 Mercruiser), and it was great, because I was able to collect all of the tools that I had dropped under the engine over the years and could not reach.

It would be a good time to clean up the engine bay, check for any structural issues with the stringers, transom, engine mounts, etc. Clean up any wiring that is messy and maybe re-paint the bilge, if needed.

You can certainly do other stuff that may be needed or to your wallet's content. Gimbal bearing, U-joints, bellows are all good fun. If they are original, then probably a good time to replace them. Make sure you have the Mercruiser Bravo Service manual, particularly if/when replacing the bellows.

How do the teeth on the Bravo drive shaft look :noidea:

 

[Bt Doctur]

you lost the coupler from mis-alignment, rotted engine bed, pulled front lags, collapsed rear mounts

 

[Rick Stephens]

First thing, before pulling motor is check alignment. If the alignment is off, then when you pull the motor you are looking for why. Bt Doc is right on.

 

[ryan04]

Thanks for the info boys. We do a lot of slow driving. Trolling speed, slow speed for the little kids on the tube etc. I’m pretty sure that’s what killed it haha.
I’ll be checking the engine alignment before I pull the engine then of course again when I reinstall it.
The boat is as clean as it gets. Stored indoors in a heated garage year round. It’s never spent any time outside overnight so I’m confident in the stringers and engine bay integrity. BUT you never know. haha. Never say never when it comes to boats.

 

[ryan04]

Oh ya! Forgot to comment on the upper yoke/drive shaft. The teeth are still there. I ran my Calipers along a few and they’ve definitely lost some material along the way. At a glance they look ok but if you look closely you can see the difference in width down each tooth. I’m swapping out that shaft as well.

 

[Searay205]

properly lubed and aligned coupler outlive 2 boat lives. your couple to young to fail unless you 5000 hours on it. why did it fail?

my guess wants lubed. when i pull my outdrive my coupler has nice gooey quicksilver smelly extreme grease on it. every single time year after year....