Mercruiser outdrive horizontal alignment

[Bobson2]

I have an '88 Cobalt with a Mercruiser 4.3 engine. The coupler splines stripped out presumably because the engine and outdrive were not aligned. I have replaced the coupler. I can align the coupler in the vertical direction by raising and lowering the front of the motor but the alignment is off in the horizontal axis. There is 1/4 inch clearance on the port side but only a bit less than 1/8 inch on the starboard side. Any thoughts on how to fix this?

 

[nola mike]

Book answer is that horizontal misalignment shouldn't happen, though I and a few others have had it happen. First steps would be to check your rear mounts and check your transom and stringers for rot. I'm not sure, but suspect that uneven front mount height can do it as well.

 

[Bt Doctur]

If you didnt replace the rear mounts too ,alignment may still be an issue

 

[nola mike]

If you didnt replace the rear mounts too ,alignment may still be an issue

Was that to me or op?

 

[Bobson2]

If you didnt replace the rear mounts too ,alignment may still be an issue

The rear mounts looked okay but when I reinstalled the engine there was a bigger gap between the port side bell housing and transom support than on the starboard side thus the mounts may be defective and the engine cocked a bit. I appreciate your thoughts.

 

[Scott06]

The rear mounts looked okay but when I reinstalled the engine there was a bigger gap between the port side bell housing and transom support than on the starboard side thus the mounts may be defective and the engine cocked a bit. I appreciate your thoughts.

Lessen the bolts and slide front of engine left or right . I was able to tweak mine by just nudging it .

 

[Bt Doctur]

The rear height between the rear mount should be the same . If different a rear mount has failed and thats why the coupler was destroyed.When replacing a coupler always replace the rear bushings.
I have found lateral alignment off on a few boats ,that is corrected by loosening and shifing the front mounts, or removing the lags, getting it into alignment and re-drilling new lag holes

 

[Bobson2]

The rear height between the rear mount should be the same . If different a rear mount has failed and thats why the coupler was destroyed.When replacing a coupler always replace the rear bushings.
I have found lateral alignment off on a few boats ,that is corrected by loosening and shifing the front mounts, or removing the lags, getting it into alignment and re-drilling new lag holes

I appreciate all the help. I liken this to getting a restaurant table to stop wobbling. The reason the port transom gap was bigger than the starboard side is that the starboard front mount was lower than it should have been and this lifted the port rear mount. Seems that the front motor mount supports were not symmetric. With a 1/4" shim under the starboard front mount, the gap on the port transom mount went away and I was able to align the coupler and outdrive. Thanks for the replies.

 

[Scott06]

I appreciate all the help. I liken this to getting a restaurant table to stop wobbling. The reason the port transom gap was bigger than the starboard side is that the starboard front mount was lower than it should have been and this lifted the port rear mount. Seems that the front motor mount supports were not symmetric. With a 1/4" shim under the starboard front mount, the gap on the port transom mount went away and I was able to align the coupler and outdrive. Thanks for the replies.

Front mounts are adjustable why’d you have to put a shim in ?

 

[Bobson2]

The bolt on the front starboard mount was not long enough. I believe that the mount supports were not made tall enough. The boat has only 261 hours of use and the coupler splines were destroyed. The transom seems solid as do the mount supports. We'll see what happens now.

 

[Scott06]

The bolt on the front starboard mount was not long enough. I believe that the mount supports were not made tall enough. The boat has only 261 hours of use and the coupler splines were destroyed. The transom seems solid as do the mount supports. We'll see what happens now.

Interesting. Nothing wrong with a shim I would guess just seems odd the boat, unless the mount was replace due to rot previously) would be that far off -1” or so right? It’s certainly not as precise an industry as you’d think so as long as your alignment was good you should be fine.
I took my drive off for the first time since repowering my boat 5 years ago (230 hrs of use since) - sea ray 200 sport , I bought it with a cracked 4.3 and swapped in a 5.0, luckily the engine mount stringers were set up for both 4.3 and 5.0 from the factory so just filling Old and drilling new holes.

I could never quite get the alignment bar two finger push in perfect , I think I had so much grease in the coupler and slightly lighter marks on the bottom ... git it as good as I could out drive on, when I checked this year the witness marks are just about perfect still slightly lighter on the bottom but coupler and splines were perfect still... drive slipped right back on with a gentle push.

 

[Bobson2]

It was only off by about 1/4". I could have aligned it as it was at the very top of the mount bolt but I wouldn't have been able to get the lock washer on beneath the lock nut. Thus the shim. We'll see how it works out.