Mercruiser 4.3 alpha 1 gen 2 alignment questions

[Blurb]

I am in the process of replacing the bellows, gimbal, bearing, u joints, trim limit and sender and the kitchen sink. First time DIY and everything is going swimmingly…except…shocker…

With the existing gimbal bearing, which is rusty and grinding due to water intrusion last summer and then sitting all winter in storage, when I insert the alignment tool (does not slide in easily takes some force to get it in all the way but it does reach the back) with some grease on it I see solid spline lines on the upper 3/4 of the circular arc with very faint light lines on the bottom 1/4 of the arc. To me this indicates that the forward mounts need to be lowered ever so slightly. My question is should I align the engine before I remove the damaged gimbal bearing or should I put the new one in and then recheck alignment? Could a bad gimbal bearing show a false misalignment?

Next question is there a rule of thumb for how many turns to effectuate a specific amount of lowering?

History time: 6 years ago I had a shop do the bellows and gimbal bearing. And they said that the engine was aligned as close as they could get it and that the adjustment mounts were maxed out.

Next question if it does need to be raised on the forward mounts how can that be done? Are there shims or extended mounts I need to get?

So my questions seem to be in divergent directions as one seems to indicate the engine needs to be lowered in the mount but the other is a what if scenario should it need to be raised. Just trying to get ahead of potential scenarios.

If it matters the boat is a 1998 Caravel 18’ bow rider.

Thanks for any assistance.

 

[Scott06]

I am in the process of replacing the bellows, gimbal, bearing, u joints, trim limit and sender and the kitchen sink. First time DIY and everything is going swimmingly…except…shocker…

With the existing gimbal bearing, which is rusty and grinding due to water intrusion last summer and then sitting all winter in storage, when I insert the alignment tool (does not slide in easily takes some force to get it in all the way but it does reach the back) with some grease on it I see solid spline lines on the upper 3/4 of the circular arc with very faint light lines on the bottom 1/4 of the arc. To me this indicates that the forward mounts need to be lowered ever so slightly. My question is should I align the engine before I remove the damaged gimbal bearing or should I put the new one in and then recheck alignment? Could a bad gimbal bearing show a false misalignment?

Next question is there a rule of thumb for how many turns to effectuate a specific amount of lowering?

History time: 6 years ago I had a shop do the bellows and gimbal bearing. And they said that the engine was aligned as close as they could get it and that the adjustment mounts were maxed out.

Next question if it does need to be raised on the forward mounts how can that be done? Are there shims or extended mounts I need to get?

So my questions seem to be in divergent directions as one seems to indicate the engine needs to be lowered in the mount but the other is a what if scenario should it need to be raised. Just trying to get ahead of potential scenarios.

If it matters the boat is a 1998 Caravel 18’ bow rider.

Thanks for any assistance.

To get more grease on the bottom you need to raise the front not lower it.
we must have the same boat. What you describe is exactly the alignment witness marks I got on mine years back When I did a repower. Never could get it to text book witness marks. Never had an issue with it in the 9 years since, drive comes on and off easily.

id put the new gimbal bearing in center it and see what the alignment looks like

 

[Blurb]

To get more grease on the bottom you need to raise the front not lower it.
we must have the same boat. What you describe is exactly the alignment witness marks I got on mine years back When I did a repower. Never could get it to text book witness marks. Never had an issue with it in the 9 years since, drive comes on and off easily.

id put the new gimbal bearing in center it and see what the alignment looks like

Hey Scott thanks for the reply but I think you may be mistaken on the direction needed to correct the alignment.

From a post in this thread:

engine alignment how to's

just got my engine alignment tool, here is where I am at ,dropped in engine measured engine mount bolts to put in approximately at same height ,the alignment tool does go in with a little wiggling should it slide in wtih no resistance or should it slide freely thanks for any advice

forums.iboats.com

Are the spline marks heavy on the top or the bottom?

If they are heavy on the top you need to Lower the front motor mounts half a turn and check again. Keep doing this step until you achieve the results listed above.
I am not terribly concerned as the current alignment worked fine for 6 years.

I also saw one video of a guy who puts the alignment tool in and turns the engine over and whacks the alignment tool as it’s turning over and it sets the gimbal bearing angle to align with the drive splines.

Check out at about the 19 minute mark. Not sure I’m ready to try that but it interesting lol

 

[JASinIL2006]

I’d install the new gimbal bearing first, then check alignment.

 

[Scott06]

Hey Scott thanks for the reply but I think you may be mistaken on the direction needed to correct the alignment.

From a post in this thread:

engine alignment how to's

just got my engine alignment tool, here is where I am at ,dropped in engine measured engine mount bolts to put in approximately at same height ,the alignment tool does go in with a little wiggling should it slide in wtih no resistance or should it slide freely thanks for any advice

forums.iboats.com

Are the spline marks heavy on the top or the bottom?

If they are heavy on the top you need to Lower the front motor mounts half a turn and check again. Keep doing this step until you achieve the results listed above.
I am not terribly concerned as the current alignment worked fine for 6 years.

I also saw one video of a guy who puts the alignment tool in and turns the engine over and whacks the alignment tool as it’s turning over and it sets the gimbal bearing angle to align with the drive splines.

Check out at about the 19 minute mark. Not sure I’m ready to try that but it interesting lol

yes I had it backwards... Point I was trying to make (seeing the comment about the shop getting it as close as they could) is you can find some that dont give textbook witness marks and work just fine for years. My boat is a great example, have 400 hrs over last 9 yrs towing a lot of skiiers yet not perfect witness marks

 

[nola mike]

IMO the witness marks are a distance second in importance to how easily the tool slides in. If the tool doesn't bind neither will the drive.

 

[Blurb]

IMO the witness marks are a distance second in importance to how easily the tool slides in. If the tool doesn't bind neither will the drive.

Thanks Mike. I’ll update once I get there. Work has slowed my progress and a few other issues have arisen that I think need to be dialed in first. Appreciate the help!