Engine Drive Coupler

LilRedNeckGirl

Petty Officer 2nd Class
Joined
Jan 25, 2010
Messages
184
1985 gm / Mercruiser 181 cid / 3.0 liter/ 140 horse power.
Running twin engines.

the Starboard engine recently had a failure in the drive coupler. The spline on the coupler were totaly gone.... THe rubber to metal bond was fine, just the spline @ all of them, were gone.... So bad, the drive would not pump water, nor turn the prop.
that engine/drive was removed a few times. first to install a SDE drive unit, the second time to remove a broken starter bolt and install new starter. The last time,@ the starter bolt, was just 4 months prior to the spline failure. At that point, the drive couldnt have had 25 hours on it. @ we fished local all last summer, with trips of no more then 15 minutes....

MY QUESTION, how and why , would the spline on the coupler be totaly gone? is this normal wear?
It seems we are talking about a simular set up @ a car transmission spline where the drive shaft connects or into the engine block. Ive never seen or heard of an auto spline being totaly eaten/worn away.
What are the causes of this type of spline failure?
Lisa
 

Augie56

Seaman
Joined
Feb 26, 2012
Messages
73
Re: Engine Drive Coupler

Running the prop into rocks will send shock waves through the outdrive and coupler, all while chewing up an aluminum prop. SS props are worse, because they don't absorb squat when it comes to smacking rocks and debris. Accumulated abuse like this can fracture the splines and start the process...once one or two shear away, the whole coupling will loosen up and self-destruct very quickly.

Not saying you operate your boat like this, but this scenario could be one reason for premature coupler failure.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Engine Drive Coupler

Couplerfailures1.jpg
 

Howard Sterndrive

Rear Admiral
Joined
Nov 5, 2008
Messages
4,603
Re: Engine Drive Coupler

a car transmission spline where the drive shaft connects or into the engine block. Ive never seen or heard of an auto spline being totaly eaten/worn away.

cars don't use aluminum splines like a boat does. Once the spline wears >30 or 40%, whether from high hours or alignment or lubrication issues, it will strip out under load
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,465
Re: Engine Drive Coupler

1985 gm / Mercruiser 181 cid / 3.0 liter/ 140 horse power.
Running twin engines.

the Starboard engine recently had a failure in the drive coupler. The spline on the coupler were totaly gone.... THe rubber to metal bond was fine, just the spline @ all of them, were gone.... So bad, the drive would not pump water, nor turn the prop.
that engine/drive was removed a few times. first to install a SDE drive unit, the second time to remove a broken starter bolt and install new starter. The last time,@ the starter bolt, was just 4 months prior to the spline failure. At that point, the drive couldnt have had 25 hours on it. @ we fished local all last summer, with trips of no more then 15 minutes....

MY QUESTION, how and why , would the spline on the coupler be totaly gone? is this normal wear?
It seems we are talking about a simular set up @ a car transmission spline where the drive shaft connects or into the engine block. Ive never seen or heard of an auto spline being totaly eaten/worn away.
What are the causes of this type of spline failure?
Lisa

Ayuh,.... Generally speakin', it's from a lack of Grease,...

Alota Trollin', 'n a lack of Grease will do that in a very short order.....
 

MarkSee

Lieutenant Junior Grade
Joined
Sep 10, 2010
Messages
1,172
Re: Engine Drive Coupler

Ayuh,.... Generally speakin', it's from a lack of Grease........

Which is why they put 1 or more zerk fittings on the coupler and maybe every few trips out a few pumps from the grease gun will help????

Mark
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Engine Drive Coupler

Which is why they put 1 or more zerk fittings on the coupler and maybe every few trips out a few pumps from the grease gun will help????

Mark

Those zirks are only on the Gen II couplers. The 1990 Alpha I and earlier couplers didn't have them.
 

MarkSee

Lieutenant Junior Grade
Joined
Sep 10, 2010
Messages
1,172
Re: Engine Drive Coupler

Those zirks are only on the Gen II couplers. The 1990 Alpha I and earlier couplers didn't have them.

OMgosh, that really sucks then.:eek:

I just figured that since I had those on my gen2 in the Maxum and I have them on the bravo in the Sea Ray.....wrong assumption:facepalm::facepalm:....but probably why pulling the drive annually on the pre-gen2 drives for maintenance is so critical.

Mark
 

LilRedNeckGirl

Petty Officer 2nd Class
Joined
Jan 25, 2010
Messages
184
Re: Engine Drive Coupler

it seems, and correct me if I am wrong, that the most probable cause for this failure is " Lack of grease". the boat is run in deep water with no major obstructions. there has been no prop damage on the aluminum props, and in fact, after the summer, the paint on the new props {4 blade 17 pitch} is not even scratched. the prior props, on the boat since we bought it 5 years ago, had only minor nicks and were replaced due to advise gathered here that a 21 pitch was too much for the 140 horse engines.
Additionaly, this year, we did NOT do much, if any trolling. Striper never showed up in numbers, we made only one bay run and with that actualy headed off shore and drift fished the towers reef. past that, we fish 99% for the big blue catfish, at anchor. @ 15 minute run to the fishing area, anchor up and spend the day.
ONE MORE QUESTION. Does replacing this part require pulling the engine from the boat...?
With the drive being removed just 4 months prior, and that drive being a 2 year old SDE drive, Its sounding more like the mechanic who installed the drive did not grease the spline properly, or used the wrong grease . Clearly, on all the outdrive and engine pulls, if worn or broken spline were an issue, a compatent mechanic would have seen the issue and replaced the part while the emgine was out. On that repair, the mechanic had forgot to attach a few things, one of which was a bracket that supported the main wire harness connector. That connector seperated and stuck us in the middle of the York river for a half hour until I found te issue.
My bottom line... I feel my mechanic 'might' be trying to get over on me. slow economy, me with a history of doing what it takes to keep the boat right & safe, regardless of cost, etc. I asked for the old parts and was told they would be left in the boat. now they just happened to be ' thrown away'. If anyone has additional comments, wisdom, etc to share, I would greatly appriciate it before I confront the boat mechanic with my feelings. Lisa
 

dubs283

Vice Admiral
Joined
Jul 27, 2005
Messages
5,058
Re: Engine Drive Coupler

it seems, and correct me if I am wrong, that the most probable cause for this failure is " Lack of grease"

yes, you should be pulling your drive at a minimum every other season (depending on number of hours used), greasing the coupler and checking engine alignment, along with the other routine maintenance items

Its sounding more like the mechanic who installed the drive did not grease the spline properly, or used the wrong grease . Clearly, on all the outdrive and engine pulls, if worn or broken spline were an issue, a compatent mechanic would have seen the issue and replaced the part while the emgine was out. On that repair, the mechanic had forgot to attach a few things, one of which was a bracket that supported the main wire harness connector. That connector seperated and stuck us in the middle of the York river for a half hour until I found te issue.
My bottom line... I feel my mechanic 'might' be trying to get over on me. slow economy, me with a history of doing what it takes to keep the boat right & safe, regardless of cost, etc. I asked for the old parts and was told they would be left in the boat. now they just happened to be ' thrown away'. If anyone has additional comments, wisdom, etc to share, I would greatly appriciate it before I confront the boat mechanic with my feelings. Lisa

time to find a new mechanic, if the coupler was that close to being worn they should have noted it and brought it to your attention

wether they are trying to pull one over on you, noone can tell except the mechanic - either way it sounds like they arent very thorough which goes a long ways in boat repair
 

LilRedNeckGirl

Petty Officer 2nd Class
Joined
Jan 25, 2010
Messages
184
Re: Engine Drive Coupler

Well, Ive emailed the boat shop / mechanic and noted my feelings that this issue should have been either caught a few months back when the engine was pulled, or that the issue was probably caused by a failure to grease the spline upon reinstalation.
Also have a huge complaint that the mechanic did not put the old part in the boat for my inspection, and instead, threw it away.
They are apparently speaking with the mechanic, and contacting mercruiser, which tells me streight up, they are flying by the seat of their britches. Ill post again when I get an outcome on this issue.
Thanks bunches to those that chimed in with their knowledge . Lisa
 

LilRedNeckGirl

Petty Officer 2nd Class
Joined
Jan 25, 2010
Messages
184
Re: Engine Drive Coupler

a question i posted that was never addressed. Does replacment of this part, require that the engine be removed from the boat? can it be done by simply pulling the outdrive and working through that opening?
 

Bondo

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Staff member
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Apr 17, 2002
Messages
70,465
Re: Engine Drive Coupler

a question i posted that was never addressed. Does replacment of this part, require that the engine be removed from the boat? can it be done by simply pulling the outdrive and working through that opening?

Ayuh,... The motor's gotta come out 1st...
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Engine Drive Coupler

a question i posted that was never addressed. Does replacment of this part, require that the engine be removed from the boat? can it be done by simply pulling the outdrive and working through that opening?

The question if the coupler can be replaced without pulling the engine is quite common, so thought I would take the time and show why the engine has to come out instead of just saying you have to pull the engine.

The engine in the picture below is out of the boat.
The coupler is shown by the red arrow and is bolted to the crankshaft with 6 studs and locknuts. There is also a shipping plug in the coupler in the picture, so you can't see the splines.
The rear motor mounts in the flywheel cover are shown by the green arrows.
The yellow arrow shows the small gap (around a 1/2" ) between the coupler and the flywheel cover.

To get to the coupler lock nuts, the flywheel cover has to be removed.
You can now see why the engine has to come out.


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