Engine Alignment Question for Mercruiser Pre-Alpha

CableGuy1978

Seaman
Joined
Jul 13, 2010
Messages
66
G'day Folks,

Just a quick question regarding engine alignment.

I recently had my motor pulled to do some work on the rear of the engine. Prior to this, the rear engine mount bolts were just a standard bolt with a nylon lock nut and a single steel washer under the head of the bolts. There was nothing between the bell housing and the transom plate.

After pulling the motor, I picked up the proper rear mount kit complete with double wound lock washers and fiber washers. I have installed the mounts as seen in a file from a Mercruiser manual, with the fiber washers and the lock washers on the transom plate. The alignment was perfect before I pulled the engine and I careful to not change the front mount to preserve the alignment. Before removing the engine I checked it with my alignment bar and marked on it how far it was in when it bottomed out in the coupler

So when I put it back together, the alignment is completely out of whack. I have the front of the motor raised almost as high as it will go, and I am able to bottom out the alignment tool, and it doesn't seem to take much force to insert it either. There are more prominent spline marks showing on the top of the bar in the grease which tells me the alignment isn't entirely correct.

It makes sense that adding the extra thickness at the rear would have an effect on the front exponentially, but the front engine mount has been adjusted up by around 2 inches higher than it was before. The adjustment will not allow me to have the spacer, lock washer and the nut to be placed under the front mount as there is no thread left there. for that, I can build up the stringer in the boat itself to allow the bracket to sit higher.

I am leaning towards removing the double wound lock washers from the rear mounts to bring the rear down more. I have been advised though that the fiber washers should be used for shock absorbing.

So my question is, is it a good idea to remove those double washers? Is it actually ok to remove the fiber ones as well? I read in a text somewhere that Merc actually omitted both washers to allow for better rear alignment, but did replace the fiber ones. But I'm pretty sure it was only for a newer style Mercruiser.

Just thought I would drop a line here first before I start turning wrenches again.

Thank you!
Jason
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Engine Alignment Question for Mercruiser Pre-Alpha

IF, you used new OEM (not aftermarket) rear motor mounts you shouldn't have the double wound lockwasher. HERE is the Merc Service bulletin covering their use.

As far as your alignment goes, if you are getting heavier marks on the top of the bar, you need to drop the front of the engine down some to equalize the marks.
Here is a thread that shows (in a video) how to get the alignment JUST RIGHT.
http://forums.iboats.com/showthread.php?t=382029
 

CableGuy1978

Seaman
Joined
Jul 13, 2010
Messages
66
Re: Engine Alignment Question for Mercruiser Pre-Alpha

Thank you Don for pointing me in the right direction!

My mounts are aftermarket from GLM. At this point, I am going to remove the double wound washers, and set every thing back in place and realign from there.

Both videos with the incorrect and correct alignments were great! I have never aligned an engine myself, but know in theory how it works. It is excellent to see just how easy the bar will slide in if the alignment is correct.

Thanks again, I'm getting closer to having this old scow back int he water! :D
Jason
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Engine Alignment Question for Mercruiser Pre-Alpha

My mounts are aftermarket from GLM. At this point, I am going to remove the double wound washers, and set every thing back in place and realign from there.

NO, NO, NO, leave the double lock washers in there like they are supposed to be, and adjust the alignment like it should be.
 

CableGuy1978

Seaman
Joined
Jul 13, 2010
Messages
66
Re: Engine Alignment Question for Mercruiser Pre-Alpha

I hope you happen to follow this thread... So I didn't get your last reply until just now and I have already been messing around with the engine. Fortunately I have a hoist, and tools and the boat is here in my driveway so it's not a big deal to lift the motor as many times as I need.

But since your last post I was trying to align the damn thing over and over by making small adjustments on the front mount until the spline marks on the top were even. It seemed like even with 1/4 turn down, on the front mount would make the difference between marks on the top and not being able to insert the bar without a lot of force, which I didn't do of course. I did remove the double wound washers, and left only the fiber washers in. The mounts are still loose and just for the hell of it I tried the bar and it went in with no force whatsoever! Even easier than before I ever touch the alignment before I started this project... The only thing I am worried about is how important those double wound washers are. Before there was never anything at all between the bell housing and the transom plate.

Anyway, as it sits now the alignment is perfect, and after all the trouble of getting to this point I hate like hell to move it. Buy you are the expert, and I am only just learning this stuff! Hahaha.

Thank you VERY much for wasting your Saturday on the forums, it is greatly appreciated to say the least! :)

Jason
 
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