Gimbal bearing alignment Bravo 1
 

In changing the plugs on my starboard engine. I noticed a top motor mount nut that was loose. Being concerned about the engine being out of alignment now. I pulled the drive off (Bravo 1) with a little coaxing it came off fairly easily. When I put the alignment tool in the gimbal bearing as far as it would go I noticed it didn't seem to be square with the face of the gimbal housing. Looking at it at different angles it looked the same. It's a left, right misalignment. With out moving the alignment tool I put a combination square on it. Indeed it is not square with the mounting face of the gimbal housing. The engine does need to be aligned. The gimbal bearing seems to be in good shape, no slop and its tight in every way I can move it. There's also no appreciable wear on the drive shaft to indicate it is in a bind in the gimbal bearing or on the splines. My questions are. Should the tool, inserted, be square with the gimbal housing mounting and drive mounting face? Is it possible the gimbal bearing wasn't seated completely therefore causing the misalignment I'm seeing? I have a pic but not sure how to upload it here.

I bought this boat at the end of last summer. First time I've had the drives off.
Thanks in advance for any help.
R

Hey I got your message - I will get back to you later or tomorrow. I am traveling. Merc has 2 methods here and one is to help with installing the engine coupler and the other is a tool to help engine alignment spot on. It is NOT your standard alignment tool used here.

You need to make sure that your motor was installed properly and level as why your alignment is off (accordingly to what you are saying). There might be a reason why it is off. So I will add - make sure you do not have rot or sag that could drop your engine especially on one side ie: rotted stringers or engine block mounts or even the transom. I would check all of that out. Rotted transoms can make engine alignment impossible.

You need to make sure your engine coupler was installed correctly and NOT warped from an improper install. You can check this by installing the CORRECT engine alignment tool - (hopefully you have that covered) With the alignment tool installed, start the engine and watch how round the alignment tool spins around. If the tool does not spin a perfect circle most likely it could be a coupler problem and possible warped or even loose.

Or make sure you have the correct inner transom parts installed and installed correctly so the engine can be mounted 100 % correctly. I will post a SB to help about how the inner transom should be set up for engine mounting. If you find all this correct in your app then i can post more.

I see your app might be a 1989 vintage - 80's and 90's boat were filled with wood that can become dry rotted or wet rotted overtime. Just saying as more times than not this is the case in older boats.

Here is a link below about the SB on the inner transom assembly to make sure you have the correct set up depending on what you have. Make sure if you have the springs needed plus they are in good shape and installed correctly (both) - If one is missing that will throw off your alignment. And if you have the newer transom assembly not uing the springs and the springs are installed that will throw your alignment off as well. Make sure the complete set up on the inner transom assembly is all correct and correct parts used. This link should help with all of that.

http://www.marinemechanic.com/merc/d...her-design.pdf

It seems the top motor mount nut has worked its way loose. Not sure how, could be a number of reasons. Looking at the mounts and comparing the two the side that had the loose nut is lower than the other side. I'm sure it needs to come up to be aligned. Looking thru the gimbal bearing at the coupler supports that.

Yes it is an 89 w 454 mags. I recently replaced the exhaust tips and there was no indication that the transom is anything but rock solid. I did everything I know to do at that time to check the entire transom for any weak spots.
I've also checked the stringers for rot as well. Best as I can with the engines still in the boat. Again get seem to be solid. The SB doesn't list 454 and mine is older than years listed does the procedure still apply? If so then I will need to purchase the update kit listed correct?

Thanks for you time and help!

By CORRECT alignment tool are you referring to the long bar that's commonly used? I will ck that as soon as time allows. As well as the rear mounts per the SB.

The 454 was not an option for installs in 2003 so the SB will not list it. You have the springs and they need to be mounted in the inner transom plate correctly - all that is shown in the SB to I posted. OLD version install versus newer version plate which is 2003 and up with no springs. Just look at the set up with the springs installed - its all in the service bulletin I posted how it needs to be.

As you say if one side is lower than the other there can be a reason as I mentioned above or someone does not have the side motor mount adjusted correctly compared to the other side. They are adjustable (side to side ). Anyways I can post the tool number to help check it more precisely. I do not remember the part number off the top of my head. Will have to look it up.

Mercruiser warns that some alignment tools are not correct to use. A few off of ebay or online that have been copied but not to exact specs so hopefully your tool is the same that the OEM spec their tool with all the correct dimensions. Just saying

I do know the tool that Sierra sells is correct but can not vouch for any online, ebay, craigslist and so on.

BUP, using a newer transom assembly w/o the springs and an older flywheel cover have any effects on alignment?

Ok that's what I thought. Just wanted to verify I was on the right track.
I figured some alignment tools were more accurate than others. I'll see if I can find dimensions of the Seirra tool and ck the tolerances of mine to make sure it's correct. There's no telling what the previous owner did or why. Hence my reasoning for going thru everything to make sure it's correct. It'll be a few days before I can investigate your suggestions. When time permits for you to look up the part# will be fine.
Thanks, You get down to Houston let me know, I'm buying the beer.

Reaper311, Nice week to work on boat in Houston area 75-80 deg. for the next week. I have an alignment tool if you need one, where in Houston you located, I'm in Magnolia area.