Is engine coupler toast?

[captainnate]

mercruiser 120 (sn 3331071)
MC1 outdrive
1972 Starcraft Nova aluminum boat

I replaced the transom plywood, and I am in the process of trying to get things back together. The alignment seems wrong. I thought it was aligned, but then I rotated the engine, and the alignment is off. Is the engine couple warped? It sat for a long time; maybe it was in the wrong position and stayed that way. Also, the front mount is all the way to the lowest point, which also seems suspicious. I have not replace the gimbal bearing yet, don't know if that matters; it seems to be in okay shape.

 

[alldodge]

Re: Is engine coupler toast?

I don't think you coupler is the issue. Were the same holes used to install the drive or were new ones made? Did you rebuild the engine mount base in front?

 

[captainnate]

Re: Is engine coupler toast?

Thanks for the response. The holes were the same in the transom. I did not rebuild the front engine mount base; do you think I should have?

 

[captainnate]

Re: Is engine coupler toast?

Maybe I should have followed the instructions in the manual exactly (not trying to be sarcastic). However, I may have to use a new wood front mount base, or at least drill new holes in the old board.

 

[captainnate]

Re: Is engine coupler toast?

I just remember something. I found a few thin shavings when I took the transom apart. I initially thought they were from the outdrive shaft, but maybe they were from the coupler. Could the coupler have a few shaved splines, and thus cause the alignment problem?

 

[thumpar]

Re: Is engine coupler toast?

Try having someone turn the engine over while watching the coupler and see if it has a wobble.

 

[muc]

Re: Is engine coupler toast?

The spines on your coupler look pretty good.
Might be able to save your coupler by setting the alignment so it is off the same amount all the way around when it’s rotated. After running it for a year, recheck and most time you will find that the coupler has straightened out.

Full disclosure: Don S (I really miss him) didn’t agree with me on this. But the factories have had me do this on new boats and I have done it on some older stuff as well.
The front mount being all the way to the end of adjustment almost always means something is wrong.

 

[alldodge]

Re: Is engine coupler toast?

Thanks for the response. The holes were the same in the transom. I did not rebuild the front engine mount base; do you think I should have?

Then I believe your stringers have an issue. Just as muc mentioned there is an issue and it doesn't look good. You fixed the transom but you probably have a bow going on with the strimgers, and they have probably been compramised by the same thing that caused the transom issue.

 

[captainnate]

Re: Is engine coupler toast?

Thanks for the help, everybody. The boat is aluminum, the stringers are aluminum; I thought stringer problems was more of a fiberglass boat issue? It seems odd to me that the alignment can be good, and then the only variable I change is turning it over to a different position (90 or 180 degrees) and then it is out of alignment. Could my rear mount bushings be bad? Could the gimbal bearing be causing this? I don't know when it was last replace, however, it appears to spin fine.

 

[captainnate]

Re: Is engine coupler toast?

it might be time to back it underneath the old swingset, hoist the engine, and take a second look

maybe the coupler is bad from sitting in a MN pole barn for 15 years

 

[GA_Boater]

Re: Is engine coupler toast?

Nate - I just saw your thread about replacing the front motor mount. Could it be that with a fresher bushing in front the motor is sitting a bit different in reference to the floor. Also with the bad transom wood prior to replacement the alignment may have been off before. And finally, just to cover all the bases here is a good write up (post #2) and a couple of videos for reinforcement of the procedure. http://forums.iboats.com/mercruiser-i-o-inboard-engines-outdrives/proper-use-alignment-bar-436175.html

The vids are by iboats member Friscoboater.

 

[captainnate]

Re: Is engine coupler toast?

Thanks again, GA. I think I will hoist the engine again and see if I can see any difference in the rear mounts. I may also use a new front mount wood support, and drill new holes. Short of that, I don't know; maybe order a new coupler. I'm starting to think outboards may have some advantages.

 

[GA_Boater]

Re: Is engine coupler toast?

Before lifting the engine away from the rear mounts, undo the front bolt, lift the front a little bit and check the alignment. When the front mount wood is replaced that's how you figure out rough placement of the front mount so that alignment is relatively close.

 

[captainnate]

Re: Is engine coupler toast?

Okay, GA, I will try that. I also want to check and see if my rear mount special split lock washers are in the right place (not real sure how they wouldn't be). I didn't glue the fabric washers in place when I did it the first time, maybe that made a difference. Maybe my rear mount bushings are bad, time for a second look. Other than that, it must be the coupler. I noticed mercstuff.com only has one kind of rear motor mount http://www.mercstuff.com/images/motormounts.jpg On-Line Catalog Page 08 : MerCstuff.Com Do I still need the "special split lock washer" if I use these new mounts?

 

[captainnate]

Re: Is engine coupler toast?

Okay, so I lifted the engine again, made sure the lock washer were in the right place, and followed the manual instructions on the order of things, and I still have the same problem. It has a sweet spot, but the rotate the engine about 180 degrees, and it is not aligned. Time to order a coupler and rear engine mounts. I don't think I made any mistakes when I built the new transom; I had 2 inches all around. I used a torque wrench on all eight bolts that go through the transom. I hope I'm not missing something simple, and replacing parts for no reason; time will tell.

 

[GA_Boater]

Re: Is engine coupler toast?

Just a thought - Is the gimbal centered? Some of the how-to's mention bumping the bar to get the gimbal centered with the coupler.

 

[84EdH]

Re: Is engine coupler toast?

Nate, when you say aligned....180 not aligned. how much not aligned? I mean will the alignment bar go in, but not as smooth? With my engine I needed a tiny nudge sideways of the front of the engine. the rear mounts would be torqued, then loosen the front mount try and nudge the engine sideways...1/16th? I used a wedge to keep the engine pushed one way, re-torque front mount. even using the same holes on transom plate could be off a tiny bit.

also: if not already re-torque the transom plate bolts. I found my transom compressed a bit after a rebuild and I re-torqued twice. hope this helps.

 

[tank1949]

Re: Is engine coupler toast?

Nate, when you say aligned....180 not aligned. how much not aligned? I mean will the alignment bar go in, but not as smooth? With my engine I needed a tiny nudge sideways of the front of the engine. the rear mounts would be torqued, then loosen the front mount try and nudge the engine sideways...1/16th? I used a wedge to keep the engine pushed one way, re-torque front mount. even using the same holes on transom plate could be off a tiny bit.

also: if not already re-torque the transom plate bolts. I found my transom compressed a bit after a rebuild and I re-torqued twice. hope this helps.

Sometimes we accidentely bump gimbal and shaft "appears" not to go in smoothy. Also, my alignment tool went in very smoothy on last install but I could never get it to come out as easy. We suspected to much grease causing sucking on tool. Be sure to use lift ring to raise and lower motor. Dont run the risk of damanging crank snout or HB.

 

[captainnate]

Re: Is engine coupler toast?

Thanks for the replies. I took the coupler off and took it to the marina. The old guy there said it looked good, pretty much new condition. I'm going to take the boat down there this week and he is going to help me with the alignment and look at a few other things. Hopefully I will make it to the lake befo summer is over.

What is HB? Crank snout? Is that the front mount?

 

[captainnate]

Re: Is engine coupler toast?

He also said the rear mounts looked good.