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Ron@LOTO

Engine coupling failure with new boat

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As a newbie I bought a new 2016 Chapparal 246 SSI, 300HP boat in Sept 2016 and the engine coupling failed at 88 hours.  The manual said to lube it at 50 hours and with scheduling I had the marina lube it at 68 hours.  Twenty hours later it failed and left my family adrift on the lake June 2018.  The marina said they had seen engine couplings last for years and they'd look for defects when repairing ($1300).  Mercury declined any warranty support.  My question:  Did I do something wrong that caused this problem?  Too much indle time?  Gear change at above a certain RPM?  Did I hit something?  

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poor engine to coupler alignment from the factory or boat builder. Lack of lubrication plays a role but if you remove the drive for it`s required service, a bad alignment would show itself

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Too much Idle time would not effect it.

Gear change above certain RPM, again, no, since your shift and engine speed are tied together through the shifter.

If you hit something hard enough to damage the coupler, chances are your outdrive / prop would have been mortally wounded and you'd know it.

As BT Doctor stated, I would bet either a faulty coupler, crappy alignment or no / little lube applied when assembled / pre-delivery checked would be the prime suspects.

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I believe my alignment was rechecked at 20 hour initial service. I would have thought they would have checked it when you had it lubed.

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23 minutes ago, jd50i said:

I believe my alignment was rechecked at 20 hour initial service. I would have thought they would have checked it when you had it lubed.

Not usually. The drive has to come off to check the alignment. Then check the alignment through the gimbal bearing with the alignment bar / tool.

Lubing it is done thru the zerk fittings in the coupler, drive installed.

Do it on mine every spring before drive goes back on (store drive on a stand in garage during winter).

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The coupler on your ride is aluminum so lubrication and alignment are critical. That said, if the proper extreme pressure lubricant is used, and alignment was checked pre-delivery as required then a coupler can go 1,000 hours and beyond as they are not the weakest link in the chain. The work boats and big block engines use stainless steel couplers and that is a nice upgrade that I hope your mechanic went with. The service manual says alignment check pre-delivery and every 300 hours thereafter, and greasing the coupler every 100 hours, or once a year, whatever comes first. It would seem that the dealer failed to check yours. The type of grease used is critical also as a simple MP lube just won't cut it.  If the initial alignment was that far off from the factory, you may also have issues with the gimbel bearing prematurely. W

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You will find out what went wrong when they replace the coupler and confirm the alignment was way off.

If they replace the coupler and force the drive back on, it will fail in short order too.

Have found the alignment off laterally also

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Wow.  I am grateful and happy to learn there is a universe of informed Chapparral  boat owners willing to help.  Thank you!  My takeaway is the engine coupling was mis-aligned either at the factory or an overlooked step by the dealer.  Neither will fess up.  Hopefully the marina that is repairing it will do a proper alignment.  Expect to see the boat back in the slip this week.  Thanks again.  

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Ron,

As others have said, it failed too soon.  That being said, a suggestion.  Specifically ask the marina/mechanic to check alignment, and align if needed.  While any good marina/mechanic should do this automatically given the outdrive is off, some folks just remove and replace.  Not necessarily because they don't care, sometimes it's simply how they were trained, lack of service manual, failure to use the service manual, interrupted by a phone call/another customer/a coworker, etc.  By having the specific discussion and asking, you'll likely get the root cause diagnosed and corrected.  Often, but not always, misalignment can be detected in how the boat performs in turns.  If the engine/drive rumble as the radius tightens (depending on speed of course), it's often a telltale.  Finally, if you have time and an interest, inspect the coupling.  Lack of/improper lubrication and misalignment usually can be seen.  If misaligned, wear is typically uneven or concentrated.  Lack of lubrication/improper lubrication typically shows a more uniform wear pattern, metal to metal scrapes, gouges, shavings... 

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