SeaRay 315 MerCruiser 4.3 EFI - after 1500 hours

Ursa Major

New Member
Jan 22, 2024
Boat Info
Sundancer 315 2007
two 220hp V6 MerCruisers
Internet sources state that life expectancy is below 1500 hours.
What happens then? a complete rebuild?
What are the costs?

The internet is wrong. There's no reason a well kept motor can't last 3,000+ hours...
Hmmm ok.
And then what? A rebuilt?
What needs to be done and what are the costs?
Hmmm ok.
And then what? A rebuilt?
What needs to be done and what are the costs?

Looks like you can get the whole shot for <$4k. So a rebuild should be less than that?

These are reman from Michigan Motorz.

Keep up on maintneance, use good quality oil/etc... as noted they'll typically last a long, long time. But of course anything mechanical can "just fail" at anytime, as well. But that's not the norm - so except for that... you keep running them until you have an issue and THEN you figure out what your options are based on what happened.
$3300 for a rebuild.
guessing labor would be 2-3 times more. Yikes!
Deferred Maintenance probably kills more boats than anything else
Typical marine engine killers are overheating (lack of cooling water - ineffective raw water pump), water ingestion (exhaust manifolds leaking internally), or running the engine near or at the top of it's rpm for most of the engine hours.

As stated, regular maintenance will minimize the first two and common sense will negate the third killer.

A friend had 3500 hrs on his 37' express and the 454 engines still ran just fine. He had it since new, took it from the Great Lakes, down the Mississipi, along the Caribbean Islands as far south as Venezuala and back. Much of his travels were at 12-1500rpm. Took him 5yrs, but was fanatical about maintenance. He said the engines were getting a bit weak but were not burning oil. Took a beating on the resale and took a while to sell, but it didn't owe him much. Just goes to say what proper maintenance and not punishing the engines can do!

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