Mercruiser Engine Coupler Failure -- How long do they last question

[Maclin]

I guess my main question is, do they (engine couplers) just wear out and spin the rubber part after a while? Or just some of them, like the one I have :grumpy: Mine spun while out on the lake last weekend cruising at near top RPM's, just starting into the 3rd hour of running that day, really nice out. Definitely the coupler, boat lost propulsion, engine overrevved and the rev limiter in full alarm caught it just before I backed it down, burning rubber smell and smoke at the back of the engine. No overheat, engine ok. Shifted ok, the boat could move under 1200 rpm's for a while as I ascertained my condition, but that only lasted a few minutes until the boat quit moving so I shut it down before an overheat could occur.

I know usually there is a series of events that can shorten the life of an engine coupler. None of those events (engine mounts shifting, water intrusion taking the gimbal out and alignment faulty on R&R, etc...) are evident so far on the failure of this one. Bryant boats are very solid, all composite structure everywhere, they guarantee engine and outdrive install for 5 years, boat structure is lifetime, so think-hoping the engine mounts shifting is not the issue, just strictly coupler failure.

Alpha One Gen2 in a 2002 model boat.
Transom S/N:
0M289557
Drive S/N:
0M405513

Took the outdrive off this morning. Driveshaft splines are fine. U-joints are fine. Bellows was dry. Gimbal bearing looks perfect, spins smooth with little effort, inside diameter surface is totally smooth. This drive was very well maintained up to this point it appears.

Can't see up into the coupler past the gimbal very well. I was expecting to see the gimbal all messed up and have to take that out then look, and post after that. I am not going to disturb any of that now. With a spotlight I caught a glimpse of those splines, looked like they still had the good square shape.

Next is to remove engine and replace coupler and then see what happens with alignment. May not be able to do that for a while due to workspace and lift issues.

Right now I am going to put the drive back on temporarily just to prevent any outside elements affecting the innards.

Please add comments and advice as I plan the next steps to get the engine out and coupler replaced then installed/aligned.

Thanks!













Shoutout to achris for the helpful video on removing these drives

 

[alldodge]

Unless there was something wrong with the manufacture of the coupler they usually last the life of the boat.

 

[Bt Doctur]

have you checked the oil level in the drive?

 

[Bt Doctur]

and the drive must be removed first before removing the engine

 

[Maclin]

Unless there was something wrong with the manufacture of the coupler they usually last the life of the boat.

That is what I thought. Seemed a forever part. Guess I won't know until I get the engine out and look at the mounts, then see what happens with alignment. Just worrying about what could have caused this.

The drive went right back on, of course the coupler was in total "forced" alignment after the event!

 

[Maclin]

Bt Doctur
Thanks, Oil level is good. I was going to leave the drive off this time but it may be a while before I get after the engine removal, so I just now put it back on for anti-weathering in case this drags out some. Looking into DIY garages with hoists and lifts. I have a chain hoist but nowhere to use it at home now. Hopefully can prepare everything and get the boat to a shop and do the engine removal and coupler R&R and reinstall engine, then get it back home for the rest.

Internal boat part removal is key here, kind of a short boat "back there". The engine will have to come up some, then move boat back some, then engine up and boat moved forward out of the way, this is the chain hoist method I envision anyways. Will have to see if a roll-around engine lift could go high enough to get the bottom of the engine up and over, boat is kinda tall on the wagon.

How long is Merc's Warranty period on these with an un-provoked failure :lol:

 

[alldodge]

How long is Merc's Warranty period on these with an un-provoked failure :lol:

I think Merc uses the "out of sight" warranty, once your out of sight ,,,, :facepalm:

 

[stonyloam]

You shouldn't need to completely remove the engine from the boat, just lift it and pull the engine ahead (or boat back) enough to access the coupler bolts. Should save you a couple of feet in height needed.

 

[Maclin]

Thanks stonyloam , I will check out the clearance once I get all the seats and stuff out of the way in the back. That would be nice.

 

[Bt Doctur]

If you had to force the drive back on for now that indicates alignment failure. See if the 2 rubber washers are able to spin or is the housing resting on them. Resting on then is a collapsed rear mount or the front mounting nuts loosened up and the front of the motor dropped.

 

[bruceb58]

Do you pull the drive annually and check alignment? If you don't, that is why the coupler failed.

 

[Scott Danforth]

I think Merc uses the "out of sight" warranty, once your out of sight ,,,, :facepalm:

its actually when the deposit check is out of site of the salesguy

 

[Maclin]

I just got the boat this March. Yearly maintenance was guaranteed to have been done, and the evidence from today supports that.

I probably posted too soon with not enough information, I had actually expected to see bad stuff when I removed the drive today. All looked great to me, and with my limited MerCruiser experience that confused me about what could have gone wrong.

The drive went back on real easy all the way first time with no Calibrated Size 9 Merc Kick Assist* today after I took it off to see what I could see. I realize with a spun coupler that does not mean a whole lot. Will know more when I R&R coupler and look at the old one then do the engine alignment.

Thanks everybody, will keep you posted.

* copyright achris

 

[HT32BSX115]

That is what I thought. Seemed a forever part. Guess I won't know until I get the engine out and look at the mounts, then see what happens with alignment. Just worrying about what could have caused this.

The drive went right back on, of course the coupler was in total "forced" alignment after the event!

My last boat (66 Marktwain, Mercruiser 150) went more than 35 years before the coupler "failed"

When it did fail, the aluminum coupler splines completely wore out like someone drilled them out! The rubber part was still intact.

If yours failed prematurely, it was likely due to mis-alignment.

I am not sure I believe the alignment *must* be checked every year on a fairly late model boat where it was aligned properly and there's no rot in the transom or stringers (engine mounts) etc......

If it's an old boat with a soft transom, the alignment might never stay "right" ....so you can probably expect the coupler to fail eventually......

 

[Maclin]

Thanks HT. That kind of thing is what I need to know, so I won't just do a quick R&R without some diagnosing at each step.

a '66 MerCruiser 150? Maybe it was really a leftover Kiekhaefer, why it lasted so long

 

[HT32BSX115]

a '66 MerCruiser 150? Maybe it was really a leftover Kiekhaefer, why it lasted so long

It was a Mercruiser #1 drive (white) + 230 cu-in GM 6-cyl.

Dad bought it new, it had 1500 hours on the engine when it (the hr meter) broke in the early 80's. I ran it until 2005 when I sold it. (39 years total) the head had never been off. It actually still ran pretty good although by then the compression was down to around 100psi on the lowest cyl!

 

[Bondo]

That kind of thing is what I need to know, so I won't just do a quick R&R without some diagnosing at each step.

Ayuh,.... There's a Few things that'll take out a coupler quickly,....
As noted above, it's Usually a lifetime part, if maintained,...

Lack of grease is a big killer of splines,... They wear to points, 'n then strip-out,....

Catchin' Air with the boat of course will wipe out a coupler, or more,...

Believe it or not,.. Trollin', as in fishin' at idle, when combined with a lack of grease is a Huge problem for a coupler,...
The constant, loadin', 'n unloadin' of the splines, wipes 'em out,...

Puttin' a short-shaft ole MC-1 drive onto a V-motor will strip out the aft end of the splines in a hurry, as only 'bout 1/2 of the spline is engaged,...
Been there, Done that,...

'n of course, Bad alignment, 'n Hard starts tear up the joint 'tween the metal spline coupler, 'n the rubber donut,...

 

[Maclin]

"Catchin' Air with the boat of course will wipe out a coupler, or more,..."

Woops. Had honestly not considered this. I hit hard once this time, so I guess I need to really look over the mounts and structure there, thanks @Bondo.

Caught air and bounced myself up off the seat and came down really hard once that last trip. It also happened on 2 previous trips this year as well. This trip's event hurt my butt and back and attachments enough to where I had to stop and figure out if I had actually done something to my back. I was going 25 maybe due to conditions already, to me it seemed a random surprise boat jumping. I am feeling it again just now as I type :wacko:

The surf boats have started showing up where I usually cruise, and even though I give them a lot of distance, the severity of the resulting multi-faceted wave interaction at a 1/4 and even 1/2 mile away is hard for me to judge.

Fortunately I found a different Park on that same favorite lake to put in at, no surfers (yet) around there. Unfortunately I found it while I was being towed in to a different ramp than I had put in at (whole other story).

 

[HT32BSX115]

Lack of grease is a big killer of splines,... They wear to points, 'n then strip-out,....

Trollin', as in fishin' at idle, when combined with a lack of grease is a Huge problem for a coupler,...
The constant, loadin', 'n unloadin' of the splines, wipes 'em out,...

I would say this is what happened to that 66 Mercruiser. I don't think there was ANY grease (yeah I know.......ANY GREASE...........!!!!!)

For the last several years all Dear old DAD did was trolling!!!

 

[achris]

Hmmm. Ok, a few thoughts. First question, what is the engine?

I had my old 165 with the original coupler at 22 years old, still going. I have a friend with a 4.3LX, 1995 (I installed the engine and still maintain it), so 22 years, still original coupler. My previous 4.3, 1994, still original coupler. My current engine, 4.3MPI 2006. I don't 'hang around', regularly hitting 40 knots, and lots of prop walking. Unless there is a mitigating reason, 20 plus years is not unreasonable.

Chris.....

EDIT: engine in signature, 2002 4.3MPI. I was expecting BIG V8 :facepalm:
Yeah, might be a case of you got 'lucky'... Merc's warranty is 'drive-way'. Warranty only exists in the drive-way and once you've driven away, no more warranty. Not sure what your consumer laws are like in USA, but in Australia, if you can demonstrate that the failure is 'premature', it's at the dealer's cost, regardless of age. That said, 15 years, although to us would constitute 'premature', a court (not familiar with these matters) could conceivably call that an 'acceptable life'...