Help! Coupler Wobble and Alignment Issue? 2005 4.3L MerCruiser Alpha 1..

[bans25]

I’ve owned this 2005 Stingray with a 4.3L Alpha 1 for three years. It’s always had a mild vibration that never went away.

Recently, the gimbal bearing started making noise. I pulled the outdrive (it was tight coming off), replaced the bearing, and checked alignment. The alignment tool was tough to insert and remove.

I adjusted vertical alignment and got it close. Using a 1” wooden dowel in the coupler, I saw possible horizontal misalignment too. I haven’t tried loosening the motor mounts from the stringers and shifting the engine side to side yet — I’m not sure how much play there is.

After rotating the crank 180°, vertical alignment was suddenly off again. I cut the dowel shorter and ran the engine with it in place — visible wobble (video coming).

So now I’m wondering if I’ve got two separate issues:

1. This wobble confirms a bad coupler correct?
2. How much horizontal adjustment is possible at the mounts, and could both issues be related?

Kids are one me to get the boat in the water.

Any feedback is greatly appreciated and honestly, a few words of sympathy at this point wouldn’t hurt either.

Bill in Southern, NH.

P.s the 1” dowel is straight/no warp

 

[Bondo]

1. Is the wobble a sign of a warped or failing coupler?
2. How much horizontal adjustment is possible at the mounts, and could both issues be related?

Ayuh,.... Coupler wabbles are never good,.......
If yer lower mounts have the hole/ slot, 1/4" to 1/2", maybe,....
Anything is Possible,......

 

[alldodge]

A 1 inch dowel rod may close but it's not within spec (note tolerances)

If coupler is warped you can rotate the engine 90* and there will be a difference in direction

You need a true alignment bar

 

[bans25]

I have a true alignment bar (and I use this to install the bearing as well). It fits in very tight and when I turn by hand it is not smooth/ feels like it binds up. When I stared the motor with the alignment tool in it causes the vibration. No vibration if I remove the alignment bar.

I’m 99.9998% sure I have a bad coupler at this point..

Hopefully, I can adjust the horizontal alignment with the slots mentioned above.

Any recommendation on couplers? The OEMs ones are pricey.

I appreciate the feedback!

 

[alldodge]

Never heard of anyone buying an after market and came back complaining, but I don't get out much sometimes

 

[nola mike]

Is it the same amount of effort to turn/pull out the alignment tool regardless of engine rotation? Witness marks on the alignment tool? Cheap ass me might be willing to go with Sierra, but that's not a job you want to redo or fail on you.

 

[Jmunk]

Is it possible the coupler sat for a period of time with more pressure on one side being out of alignment. Have you thought about getting the alignment as close as you can and running it for a bit to see it gets any better and “re-centers”. Just something that came to my mind, may not work. Just a thought. Worst case you’re pulling the motor anyways.