3.0 Merc Coupler broken?

akaSharkey

Cadet
Joined
Feb 12, 2006
Messages
25
Last year I noticed a grinding noise coming from the rear of the engine. Limped the boat back to the trailer drove home and winterized her and put her in the garage for the winter. Upon teardown found that all three corners where the coupler mounted to the flywheel were cracked. I ordered a replacement coupler, but before installing, was wondering if there was a cause that needs to be looked at or if it is normal for a coupler to fail. The boat is 13 years old, and sees moderate use every year. ?? Brian
 

wncrjb

Petty Officer 1st Class
Joined
Aug 29, 2006
Messages
253
Re: 3.0 Merc Coupler broken?

I would check to make sure your engine is in alignment, that might be one reason.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: 3.0 Merc Coupler broken?

Howdy,

No, It's not normal for a coupler to fail. The 1966 Marktwain I got from my dad (who bought it new) had a coupler last from 1966 to 2005 when I replaced it.

If it failed, you have some problems there that could be either rotten front (stringers) engine mounts or maybe it was never aligned properly. Poor alignment usually destroys couplers.

It's usually the rubber part of the coupler that fails....not anything metal. If the metal mounting area failed then it probably wasn't bolted onto the flywheel tight enough.

Replace it of course, but when you do you might want to check the engine mounts (the wood/fiberglass below the mounts) for rotten/soft wood because if somethings rotten in Denmark....your new coupler won't last long either.


Cheers,

Rick
 

akaSharkey

Cadet
Joined
Feb 12, 2006
Messages
25
Re: 3.0 Merc Coupler broken?

Thanks for the replys

All the mounts are solid. I had the outdrive off last year, and replaced the waterpump in the outdrive, aligned it when i put the outdrive back on. Dont know I will double check everything before reassembling. The only thing i noticed was the rubber nubs that go between the coupler and flywheel were missing. After I got it apart, Im just glad I made it back th the trailer last year. All three corners were broken off the coupler. Brian
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 3.0 Merc Coupler broken?

Rule of thumb.
If you loose a coupler, replace the rear engine mounts. 90% of the time an untrained, and sometimes an untrained eye can't see a mount problem.
You have to pull the engine to replace the coupler, and the rear mounts. It just seems smart to change the mounts at the same time you do a failed coupler. No matter what caused the coupler to fail.
 
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