Engine hours
- Thread starter ccdjoe
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In my experience hours is a mostly useless metric for marine gas engines. Useless because marine engines don't typically wear out to the point they need a rebuild - due to rings, bearings, valves, timing chain, cam lobes getting worn down beyond spec. That would take probably take somewhere around 10,000 hours, I would guess. I've read that diesel engines should be able to run 30,000 hours before a rebuild is needed. Of course very few recreational boats ever see hours like that - it would take 200 years.
Marine engines blow up, most commonly because they ran lean on water contaminated gas and a piston exploded, or the exhaust manifold / riser rusted and dumped water into the cylinders. Or they were installed wrong to begin with, and water kept backing up into the exhaust. When that happens, it is not related to number of hours on the blocks.
Marine engines blow up, most commonly because they ran lean on water contaminated gas and a piston exploded, or the exhaust manifold / riser rusted and dumped water into the cylinders. Or they were installed wrong to begin with, and water kept backing up into the exhaust. When that happens, it is not related to number of hours on the blocks.
Hours is helpful if you want to keep maintenance records with it. It's also helpful if you think you need to change your oil after x hours mid-season. Outside of that, it's by total number of years or some other issue as Alk noted above.
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Marine gas engines fail for any number of reason including corrosion from lack of use and the same wear and tear as road going engines. Gas engines work a lot harder in boats than in cars because of load level. In most cars engines are almost never running for hours at 75% load... still corrosion is the silent killer with humid saltybair coming in the cylinders they open valves. 1000 to 2000 hours is probably realistic
Diesels will also suffer from corrosion and lack of use. 30 00 hours ? Never in recreational use, not just because nobody will put that many hours in their lifetime but because recreational marine diesels are rated at higher HP than the commercial version. 30000 hours in commercial use, yes with proper maintenance that s possible
Depending on how the boat is operated, you can get anywhere between 1000 and 10 000 hours out of a recreational marine diesel. Power to CID ratio is one of the critical factor... push an engine close to the magic 1 hp per 1 CID and life expectancy will plummet. Look at older Detroits for instance... highly tuned 692 popular in smaller sportfish in the 80s or 90s would often need rebuild between 1000 and 2000 hours especially since most sportfish run hard to and from fishing ground. Same engines in cruisers typically run at lower speeds for comfort would last much longer
Also, maintenance requirements in many diesels are given in hours OR gallons burn whichever come first. Harder you run, harder on the engines.
Personally I ve had diesel gensets with 10 000 still running great... when the boat I used to run sold a couple of years ago, the Cat 3412Es has 5500 hours and paaaed survey and oil analysis with flying colors. But the boat was never pushed hard with at least half the hours at hull speed and because it had the larger optional engines even on plane at 22 kts we were running at about 55% load. Big difference in longevity.
So bottom line... many many factors will affect how long engines last
Diesels will also suffer from corrosion and lack of use. 30 00 hours ? Never in recreational use, not just because nobody will put that many hours in their lifetime but because recreational marine diesels are rated at higher HP than the commercial version. 30000 hours in commercial use, yes with proper maintenance that s possible
Depending on how the boat is operated, you can get anywhere between 1000 and 10 000 hours out of a recreational marine diesel. Power to CID ratio is one of the critical factor... push an engine close to the magic 1 hp per 1 CID and life expectancy will plummet. Look at older Detroits for instance... highly tuned 692 popular in smaller sportfish in the 80s or 90s would often need rebuild between 1000 and 2000 hours especially since most sportfish run hard to and from fishing ground. Same engines in cruisers typically run at lower speeds for comfort would last much longer
Also, maintenance requirements in many diesels are given in hours OR gallons burn whichever come first. Harder you run, harder on the engines.
Personally I ve had diesel gensets with 10 000 still running great... when the boat I used to run sold a couple of years ago, the Cat 3412Es has 5500 hours and paaaed survey and oil analysis with flying colors. But the boat was never pushed hard with at least half the hours at hull speed and because it had the larger optional engines even on plane at 22 kts we were running at about 55% load. Big difference in longevity.
So bottom line... many many factors will affect how long engines last
- Joined
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For gas engines(my only experience) that 2000 hour number has been thrown around for forever. I really just think of it as another gauge of what I'm looking at when assessing a boat.
As long as there's no blow bye and the compression and oil pressure is good I believe there isn't anything you cant fix on a motor with it still in the boat.
As long as there's no blow bye and the compression and oil pressure is good I believe there isn't anything you cant fix on a motor with it still in the boat.