alignment issue

dwheeler7676

Cadet
Joined
Dec 26, 2007
Messages
14
I had to pull my lift-kept 1990 Merc 5.0LX/Alpha1 this spring to replace a leaking gas tank (which may have have been hastened by water leaking into the bilge (while running?) over several low-hour seasons in the brakish waters of the upper Chesapeake Bay). While the engine was out, I also pulled off the inner/outer transom plates to replace the lower (anodic) through-bolts, transom seal, bellows, manifolds, water pump, etc. Other than time (it ultimately took all summer), everything went smootly until re-installing the transom plates and engine itself. (The transom plate seal, transom plate itself and all glass/wood/stringers/etc. looked great - the persistant leak appeared to be due solely to the water pump.) Then;

A) With time (summer) running short, I cracked the inner transom plate while torquing those bolts to the proper spec (too much anti-sieze?). After a liberal dose of cussing (which, not surprisingly, had no effect), I resigned myself to continuing on, leaving the now properly torqued but (hair-line) cracked inner transom plate in place, and reinstalling the engine/outdrive.

B) After re-installing the engine, an initial visual check of the aligment revealed the engine splines to be centered (left and right), but 'low' with respect to the gimbal bearing - no amount of adjustment by the front engine mounts could fix this. I do not have an "official" alignment tool (yet), but was using a friend's (aluminum and plastic) home-made tool which agreed with my visual assesment, though it would nonetheless seat fully. A drive shaft from an old outdrive confirmed the problem, as did a fitted rod seated deep into the engine splines. (The centerline of the engine splines point or run about 1/4" above the lower inner edge of the gimbal bearing, instead of running through the center of it.)

With time (and warm weather) running out, I reinstalled the outdrive despite the misalignment (after a little extra 'persuasion' - rocking, shoving and bumping - but not more than I've used in the past to reinstall the outdrive after it's yearly maintanance) and brought the boat home for the winter. (I am assuming, with the engine centerline sitting "low" wrt the gimbal bearing centerline, that the gimbal bearing is now supporting the rear on the engine to some degree, significantly increasing wear on the bearing, likely resulting in early and immintent failure.

Question(s):
-Since the rear engine mounts sit directly on the inner transom plate (properly atop the fiber and coiled washers) how can the alignment be off (low) so that the 'holes' (engine splines and gimbal bearing) don't line up? The front engine mounts can adjust for the "tilt" of, but not (centerline) "position" of the engine splines, correct? (The rear engine mount washers, fiber and coil, *are* in place.)

-Is this amount of misalignment 'gross', or 'typical', in a practical sense? (Obviously it is not "preferred".)

-Despite the inner transom plate being cracked, the through-bolts securing it to the outer transom plate shoud 'fix' the alignment of the two plates (hence the gimbal bearing position), correct? I don't think hairline cracks in the iner transom plate (located below the rear engine mounts) should be the cause this misalignment. Do I really need to replace the inner transom plate for hairline cracks below the rear engine mounts?

-Comments/Recommendations? (I am fully resigned to having to pull the enine/outdrive again before putting boat back into full service... next year!)

Thanks in advance.
 

JCF350

Lieutenant Junior Grade
Joined
Oct 21, 2007
Messages
1,149
Re: alignment issue

A) With time (summer) running short, I cracked the inner transom plate while torquing those bolts to the proper spec (too much anti-sieze?). After a liberal dose of cussing (which, not surprisingly, had no effect), I resigned myself to continuing on, leaving the now properly torqued but (hair-line) cracked inner transom plate in place, and reinstalling the engine/outdrive.
These BREAK when flexed usually due to soft wood in the transom.

B) After re-installing the engine, an initial visual check of the aligment revealed the engine splines to be centered (left and right), but 'low' with respect to the gimbal bearing - no amount of adjustment by the front engine mounts could fix this. I do not have an "official" alignment tool (yet), but was using a friend's (aluminum and plastic) home-made tool which agreed with my visual assesment, though it would nonetheless seat fully. A drive shaft from an old outdrive confirmed the problem, as did a fitted rod seated deep into the engine splines. (The centerline of the engine splines point or run about 1/4" above the lower inner edge of the gimbal bearing, instead of running through the center of it.)
Do not use visual use the correct tool.

Your gonna end up wiping out the splines in coupler before you hurt the bearing. You need to take this back apart and fix it.
 

95yj

Petty Officer 1st Class
Joined
Feb 21, 2007
Messages
279
Re: alignment issue

You need to start with the correct alignment tool. Don't know how far off your alignment appeared to be, but when replacing the gimbal bearing, you need to use the alignment tool to "center" the bearing, then proceed with the alignment. If the engine appeared to be low, maybe it's just because the gimbal bearing wasn't seated properly in its race. Get the proper alignment tool for around $50 and pull the drive and check.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,464
Re: alignment issue

Ayuh,........

Getting it Right using Broken Parts,+ Bubblegummed Tools Probably ain't gonna Happen.......

As noted,.... Transom Plates Don't just Crack without a Reason,....
It has to sit True,+ Flush on the transom...... It appears your must have been Cocked,... No Way it should have Cracked with 45ft.lbs. of torque......
And,.......
This is Probably Why you can't get the right/left Alignment Right......
 

dwheeler7676

Cadet
Joined
Dec 26, 2007
Messages
14
Re: alignment issue

Re: Crack without reason:

The transom plate was sound, hard as a rock (there was no leakage around the transom seal, bottom bolts, etc). However, as I stated, I was advised to liberally coat the through bolts with anti-sieze, which can affect the actual torque achieved, so it is possible that the bolts were overtightened, in spite of using a torque wrench set to the correct setting. So my next question is, so what?

It the plate is now cracked, what difference does it make? The bolts are all tight (maybe over tightened) so the transom seal shouldn't leak, and the inner/outer transom plates are aligned (via the through bolts) so everything should line up? Other than the emotional distress of knowing that it is cracked, what problem do those hairline crack(s) actually cause? I'm looking for knowledgeable experiance here, not warm feelings (I already acknowledge that I should pull it again next spring and replace it, but what is going to keep the same (alignment) problem from reoccurring if replacing a cracked transom plate has no effect on engine/drive shaft alignment?)

Thanks in advance.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: alignment issue

If it cracked, it was installed improperly. How it was installed improperly and the results of it being installed that way is impossible to say.
Also, antisieze will not cause an overtorque condition, even if you use a whole bottle on one bolt/stud.
 

dwheeler7676

Cadet
Joined
Dec 26, 2007
Messages
14
Re: alignment issue

Re: Gimbal bearing alignment:
The gimbal bearing was purposely *not* removed so that when reinstalling everything, it's position would not be a variable. The misalignment was, however, evident as soon as the engine was lowered back in place. Only *after* the alignment was checked and found to be off was the gimbal bearing removed, repacked and replaced, while the misalignment remained unaffected.

Re: Tool: I've seen a couple of different tools available, some are just a rod with the proper splines and shaft diameters (i.e., resembling a drive shaft), while others have a collar that slides on (or is affixed?) near the gimbal bearing. What is the proper type? I'll likely purcahse or borrow one when I pull it again in the spring, but how is it used? (Simply slide it in through the gimbal bearing into the engine coupling, so if it slides in fully then alignment is okay ? (Go/No-go?) Please advise.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: alignment issue

Re: Gimbal bearing alignment:

You DO NOT align the gimbal bearing as such, you align the engine coupler to the Gimbal bearing. That is done using the front motor mounts.
 

dwheeler7676

Cadet
Joined
Dec 26, 2007
Messages
14
Re: alignment issue

Don-

'Check' on gimbal bearing not being aligned as such, but since it is free to rotate [nearly] 360 degrees in any direction, it needs to be pointed in the right direction (or "aligned") with the engine coupler for the tool (or driveshaft) to slide in correctly, that's all I was saying about that (usually inserting the tool, or driveshaft, into the couple accomplishes that, whether while checking with a tool or installing the outdrive).

The discussion keeps going in circles around words like "checking" and "proper"... the real question for the expert is, "What if, when the alignment is checked, the engine coupler is found to be sitting too low with respect to the gimbal bearing?" Currently I am experiancing this condition, and no amount of adjusting the engine mounts brings it into 'alignment', whether checked with the naked eye, driveshaft, or tool.

The engine mounts can only correct the tilt, or angle, of the engine coupler by effectively raising or lowering the forward port or starboard corners of the engine. The rear of the engine is sitting directly on the inner transom plate (atop the fiber and coiled washer, that is) so the engine coupler should be fixed and centered with respect to the height and position of the gimbal bearing. (A) Has anyone else ever seen this happen? (B) If so, why did it occur and what was the cure? (C) If not, why again, and... (I assume the recommended cure would be to do it "properly" and "check" again). Note: A valid expert's answer to 'A' is, "No, I have never seen this happen."

Thanks for hanging in there.
 

95yj

Petty Officer 1st Class
Joined
Feb 21, 2007
Messages
279
Re: alignment issue

The proper tool is Merc p/n 91-805475A1 and fits all Pre, Alpha Gen I & II and Bravos. Unfortunately, it's $100 while there's a lot available for around $50. The ones with the collar are for the TR and will fit your setup, but you don't need to spend the extra money on them.

The reason I mentioned spinning the bearing is the same thing you just referenced. Since the rear of the motor is bolted to the housing, then the coupler can't be sitting lower than the gimbal bearing unless something isn't installed correctly or else something is broke.

That said, I'll butt out of this and let Don say something more intelligent than I can on the issue.
 

dwheeler7676

Cadet
Joined
Dec 26, 2007
Messages
14
Re: alignment issue

95yj-

Thanks for the tool info (esp. part no's), and also words about coupler/bearing (which mirror mine), despite the lack of an answer or cure for my dilemma.

Guess I'll figure it out in the spring when I get to go at it again!

Thanks again.
 

oops!

Supreme Mariner
Joined
Oct 18, 2007
Messages
12,932
Re: alignment issue

dwheeler
welcome to i boats.

i can hear from your tone your getting frustrated.
you must understand, we are not standing there looking at it. your discriptions are very good. check this, or try this, is what a mechanic at a shop is gonna do before he comes to a conclusion.
the people that have responded to you so far repersent many years of trained, and practical expertiece,
may i suggest to re-read their posts, gleaning any *** bit of info....and check it on your boat ! then tell us what you saw and we can go from there.
personally i would pay serious attention to the transom
as bond-o said....it cracked for a reason.
but i dont think the damaged plate will cause you grief, but the allignment will, if not this season, next.
oops
 

JCF350

Lieutenant Junior Grade
Joined
Oct 21, 2007
Messages
1,149
Re: alignment issue

Re: Crack without reason:
It the plate is now cracked, what difference does it make?

Those plate don't just crack. If you see a crack it is broke. Depending on where it is broke it could give you alignment problems.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: alignment issue

May I chime in with a suggestion?

If the engine is sitting lower than before, and you put new rear mounts in, then it is possible they you didn't install the spacers above the mounts. This would put the engine about 1/8" too low and no amount of adjusting of the 'front' engine mounts, on the side of the engine, would get is right. This all assumes that the crack in the transom plate is below the line of the rear mounts. If the crack is above, then all bets are off.

Chris................
 

dwheeler7676

Cadet
Joined
Dec 26, 2007
Messages
14
Re: alignment issue

Thanks again to all who have responded to date. All your responses have been gratefully and thoughtfully considered. Actually, I am not getting frustrated, just trying to lead the discussion towards a meaningful end - knowing full well that diagnosing such a complicated issue is difficult at best, if not impossible, over the internet - this while acknowledging that a job not done properly is an incomplete job.

What I have gleaned from the preceeding posts (though not all might agree) is that a crack in the [thin] inner transom plate casting [*below* the rear engine mounts] would most likely *not* cause an immediate problem all by itself, at least not with the aligment of the engine coupler to gimbal bearing (since the mounts are located above the cracks - and the through bolts align the inner and outer transom plates, which in essence fix the relative postion of the gimbal bearing wrt to the rear of the engine/coupler).

Note: I did assure and verify the correct placement of the two washers (fiber and coil) between the rear engine mounts and the transom plate as well as the spacers above, hence this confusion. The transom itself was/is in great shape (I have seen comparatively 'soggy' ones), solid and without any signs of a wet or compressive core (apparently the rubber transom seal never leaked as originally feared and I replaced the two lower anodic bolts in time). Other than a liberal dose of anti-sieze on the transom plate bolts and being interrupted (several times) while gradually tightening them (possibly causing one side or bolt to be tightened more at one time before reaching the recommended torque), I have no explanation for the plate cracking - possibly there was some 'give' to the transom that wasn't obvious. The gimbal ring position being relatively low wrt to the engine coupler (coupler centerline was about 1/8" above the lower edge of the gimbal bearing - or about 1/2" - 3/4" too low) was evident upon first dropping the engine in place and even running the engine mount bolts all the way down (or up) could not correct it. The driveshaft *did* however slide into place when installing the outdrive, albeit with a little extra persuasion (done just to get the boat out of the 'marina', trailered home, launched and put back on my lift for the winter).

Since *no* one (except me) has said that they've seen this type of alignment issue before, I must conclude it is rare at best and (to date) unexplained. I will pull the engine again, replace the transom plate, be very, very careful to evenly torque the transom plate bolts, being sure all washers, etc. are in place before checking engine alignment (using a proper alignment tool)... in the *spring*, that is!

Thanks again, everyone! (Wish me better luck, next time.)
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: alignment issue

I suspect you have mis-understood my last post. I am not referring to the fibre washer with the double coil washer inside it. I have read your posts that you installed that. I'm referring to the spacer inside the flywheel cover that goes in before you press the rubber mounts in. Refer to the diagram, item #3....

Chris.........
 

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flabum

Chief Petty Officer
Joined
Feb 17, 2007
Messages
567
Re: alignment issue

The rear mounts are secured by two bolts, washers and spacers. If you put the washers under the spacers, you could be pushing the back of the engine down causing your problem. The washers go above the spacers.
 

flabum

Chief Petty Officer
Joined
Feb 17, 2007
Messages
567
Re: alignment issue

I suspect you have mis-understood my last post. I am not referring to the fibre washer with the double coil washer inside it. I have read your posts that you installed that. I'm referring to the spacer inside the flywheel cover that goes in before you press the rubber mounts in. Refer to the diagram, item #3....

Chris.........

Chris, isn't that mount off-center as well? Doesn't it have to go in one way?
 

wil7483

Petty Officer 1st Class
Joined
Jan 19, 2007
Messages
377
Re: alignment issue

The entire thread is moot....the author doesn't seem to understand the importance of the alignment tool. W/O using the proper tool to check his alignment he will never get it correct. He said himself that he "eyeballed" it.

If he put the spacers and washers in correctly then the engine will sit at the proper height and all he needs to do is use the proper tool, i.e. not his eyeballs, and align the engine by raising or lowering the front of the engine.

Everything else is symantics. He has to invest in the proper tool to do the job and stop trying to determine if it is correct with his eyes and makeshift materials. Trust me, if the engine was 1/4 inch lower or higher as you presume then the outdrive wouldn't have gone on no matter how much you beat on it! I know this from experiance.

Get the right tool, a merc manual, and do the job correct.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: alignment issue

Chris, isn't that mount off-center as well? Doesn't it have to go in one way?

As far as I remember they are symmetrical in all axis. There is no 'upside down' or backwards. You have just got to be aware that the spacer must go in, or the engine coupler will be about 1/4" lower than the gimbal bearing.... Hey wait, isn't that the poster's problem?

Chris............:D:D:D
 
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