Mercruiser 140 coupler transom gimble (spun another coupler)

[Wakesilver]

Happy Memorial Day!

We took the boat out for its first run of the season yesterday. I replaced the coupler and the rear mount bushings back in 2009, using an alignment tool and advice from here and other places. I got somewhere around 30-40 hours on the replacement. As we were doing a victory lap the boat stopped moving at 3000rpm and rev'd high. And then there was that old familiar smell of burning rubber. Darn. Still thankful that a spun coupler often re-engages at a lower rpm, we throttled down and puttered back to the boat launch and trailer.

I hear if they are poorly aligned they fail within a couple hours. I thought I was in the clear since I used the tool and such and had entered my third season. I don't remember the tool sliding in "like butter" but I remember moving the front mount up and down until I got it as free as I could and the witness marks in the grease seemed pretty even all the way around.

I am wondering-hence the post-how not to have this happen again. Could I be also seeing the symptoms of other trouble, like a soft transom or stringers or a worn gimble bearing? The front mount of the motor never looked quite right to me either, previous owner was in there and so was I trying to get it right last time. It there a way to check the initial position with rulers or lasers or ? to make sure that I am within reason before trying again?

I like tinkering, but splitting the drive and pulling the motor every three years is a little much.

Thanks!

 

[Don S]

Re: Mercruiser 140 coupler transom gimble (spun another coupler)

Did you grease the splines? A coupler with the splines worn out usually indicates lack of lubrication, and not being aligned properly makes it worse. The splines on the shaft also have to be in good shape, or they can increase the wear on the coupler as well.



Might want to look at this videos in this thread http://forums.iboats.com/showthread.php?t=382029

 

[Wakesilver]

Re: Mercruiser 140 coupler transom gimble (spun another coupler)

Thanks for the video links, Don!

Mine did not slide in as easily. The outdrive splines looked OK back in 2009 and were greased well. I will report back once I pull the drive. Would a gimble/gimbal bearing replacement be in order after going through a couple couplers? My hunch is that when the previous owner redid the floor the alignment was tweaked and that my last go wasn't as good as an improvement as I had hoped.

 

[Don S]

Re: Mercruiser 140 coupler transom gimble (spun another coupler)

The outdrive splines looked OK back in 2009 and were greased well.

Greasing those splines is a yearly job, and the alignment has to be right.

No, the gimbal bearing is not the problem.

My hunch is that when the previous owner redid the floor the alignment was tweaked and that my last go wasn't as good as an improvement as I had hoped.

Doesn't really matter what was done, if the alignment is right and the coupler is greased yearly, it should last a long time.

 

[Wakesilver]

Re: Mercruiser 140 coupler transom gimble (spun another coupler)

Outdrive is off. Almost forgot to shift into forward...
-Splines look good, plenty of pretty blue grease on them and they measure the same front to back.
-Dusted off the alignment tool and tried it with remaining blue grease. Tool starts ok but does not finish easily. Very short grease marks on the the top, long ones on the bottom.
-Small amount of water in bellows
-Port trim cylinder does not collapse as much as the starboard by 6-8". Trim pump made some funny noises as I tried to level them to each other. Did not succeed. Thinking I am going to need flush the fluid and have a look at them too...

 

[Don S]

Re: Mercruiser 140 coupler transom gimble (spun another coupler)

-Port trim cylinder does not collapse as much as the starboard by 6-8". Trim pump made some funny noises as I tried to level them to each other. Did not succeed. Thinking I am going to need flush the fluid and have a look at them too...

They never will run equal when unhooked. The one that moves the easiest will move first, then the other one will catch up. Every time.

-Small amount of water in bellows

Any water is too much.

Tool starts ok but does not finish easily.

There is your answer, it's out of alignment.

 

[Wakesilver]

Re: Mercruiser 140 coupler transom gimble (spun another coupler)

Thanks Don. Yep. I blame it all on the last guy who worked on it...me.

There was some white powdery junk down by the water pickup o-ring and over by the shift lever. Is that a symptom of anything?

Since it looks like we're going in deep, is there anything else to check right away?

I have a kit for the drive gasket/o-ring but do not have a coupler and for sure not a bellows kit, tool, and adhesive.

 

[Wakesilver]

Re: Mercruiser 140 coupler transom gimble (spun another coupler)

New coupler is in.

Did I read other posts correctly that the gimbal bearing may need to be horsed with the bar to get things to align?

Also, front motor mount is missing the #2 spacer (25-35903). Should the entire top section of the motor mount be rigid? Seems like I have 1/4" or so play because of the missing piece. Thinking about doing a new 32833 mount and missing piece and the rubber spacer washers too.