What are High Engine Hours??

[Lepke]

It depends on the engine mfg, how you do your maintenance, and how hard you push your engine. Most yacht engines should go 10k hours or more with good care. Some do more. Turbo engines can do a lot less if you hot rod.
I have old Detroit Diesel naturals. Built in 1947 and rebuilt once by me about 10 years ago. They had way more hours than I could document at 30,000.

Instead of rice burners, Perkins, Lehmans, and especially Volvos you ran smaller Detroits like 353s, once rebuilt, they would last the life of the boat and longer.
When I was a fisherman, there were thousands of 671s in fishing boats that had never been overhauled. Most were bought as surplus running engines and only got their oil changed and the occasional tune up.

 

[SteveK]

When I repowered my boat, the display has a built-in hour meter. As you say, they're generally of poor quality and die prematurely. So I bought a quality hour meter and wired it to the ignition switch.

View attachment 139161

Ted

Thanks Ted, now I have seen one.

 

[fryedaze]

We are at 7200 hrs on twin 210hp 6BT5.9Ms. that works out to 12,600 gals of fuel each. They run at 1500 rpm and burn 3.5 gph combined. Oil changes 200-250 hrs (twice a year). Oil samples are near perfect and there is no oil consumption. I like the 20,000 to 30,000 gallon before overhaul. That would work well for us[emoji16]

 

[PM]

A good Diesel should run at a minimum of 25,000 hours, most gassers will be ready for rebuild at 5,000.

pete

 

[mvweebles]

A good Diesel should run at a minimum of 25,000 hours, most gassers will be ready for rebuild at 5,000.

pete

And you base this on what?

 

[Eli27]

What do people feel are high engine hours on a 1985 350HP marine diesel?

People with 1980s engine feel free to give the HP, hours and how your engine is holding up?

BTW - I did a general google search and got answers from 5,000 to 15,000 hours. Of course the thing is hours tell nothing about how the engine was operated, just how long it was.

High engine hrs? Here is a real world example on a Ford leyman. The engine hrs is 2750. Fairly low hrs. But its from 1978. OK, not a big deal right? Well i know the boat sat for the last 7yrs and prior to that it was run twice in 4.

What does that mean? It sat alot. After 7yrs the engine oil is gonna be mud. When the engine sits that long with no lubrication, initial startups are extremely hard on engines because of the non existent oil on engine parts.

Moisture plays a huge factor. And that can turn awesome long running engines into grenades.

So how many hrs is high? The is one guy on here who had 30hrs on a rebuild and the engine locked up. I have a friend who has a 1981 Grand Banks with twin leyman 120's. 13000 hrs and are original. I know people who have replaced them with 4k on them.

And be careful when they say "oh i take care of my engine. Its very well maintained" Somebody who changes his oils every 200 miles and runs his boat 50hrs a season for that 1 or maybe 2 trips a year, that engine is not being run proplerly for longevity.

Maintenance AND running your engine properly are the keys to longevity.

My .02 from engines ive rebuilt and talking with builders.

 

[mvweebles]

It depends on the engine mfg, how you do your maintenance, and how hard you push your engine. Most yacht engines should go 10k hours or more with good care. Some do more. Turbo engines can do a lot less if you hot rod.
I have old Detroit Diesel naturals. Built in 1947 and rebuilt once by me about 10 years ago. They had way more hours than I could document at 30,000.

Instead of rice burners, Perkins, Lehmans, and especially Volvos you ran smaller Detroits like 353s, once rebuilt, they would last the life of the boat and longer.
When I was a fisherman, there were thousands of 671s in fishing boats that had never been overhauled. Most were bought as surplus running engines and only got their oil changed and the occasional tune up.

When I drove for a dinner charter yacht company on SF Bay, one of the boats was an old Pacemaker 65 with a pair of 671s that had been in charter service for over 10 years. The boat was well maintained to avoid missing a charter due to breakdown. While I was there, engines were scheduled for overhaul with about 16k hours on them. I don't recall why they were scheduled for overhaul - boat remained in service until end of busy season, which is when I left to focus on deliveries.

15k feels about right rule-of-thumb interval for rebuild interval, assuming decent maintenance. Maybe a bit less for my Perkins 4.236.

In my opinion, the reason there is so little consensus on this topic is because recreational owners log so few hours (OC Diver being a notable exception). Ultimately, I'd guess that 99% of rebuilds for boats like TF members generally own are caused by some sort of adjunct failure or drastically deferred mainteance; or as a prophylactic such as when pulling an engine to replace fuel tanks. Wear and tear/high hours account for a miniscule number of engine rebuilds in our category

Peter

 

[tiltrider1]

While not a normal boat engine and nOt in a marine application, I personally put 28,000 hours on an Isuzu 5 liter diesel. The engine worked fine when I sold the truck. Smoked a bit if left idling but no power issues.

 

[Jeff F]

Wear and tear/high hours account for a miniscule number of engine rebuilds in our category.

I think that's right.

Just to point out the obvious here, we're talking about equipment manufactured ~40 years ago. You're potentially facing shortages of parts and skilled labour.

I've come to evaluate older boats at least in part on how much it would cost to replace/rebuild the engine. My current boat scores very well in that regard.

Put another way, what's the value of the boat with a bad engine, or what's the plan for remediation?

 

[High Wire]

Sometimes it’s not wear that leads to replacement. It’s the lack of availability of parts. Lehmans, Perkins, Cummins, and Cats still have good parts availability for legacy engines.

 

[Comodave]

Bob Smith told me that the watermen in the Chesapeake would bring in their Lehmans in around 20K hours for a preventative rebuild. But they were running their engines much more regularly than pleasure boaters so I would expect their engines to go longer.

 

[Pack Mule]

As an example, a Cummins 6B (natural 135 HP) could still be good with 20K hours.

A 6BT (turbo 210 HP) could be still good at 10K hours.

A 6BTA (turbo, after cooled 370 HP) might not last 5K hours.

Ted

Thanks Ted. I’m looking at a 6bt 210 with 6500 hrs. We might just get back in the trawler saddle.

 

[O C Diver]

Thanks Ted. I’m looking at a 6bt 210 with 6500 hrs. We might just get back in the trawler saddle.

I have a 6BT in my Dodge pickup. It had 525,000 miles(10,000+ hours) on it. If you take care of them and change the oil regularly, they'll last a looong time.

Ted

 

[rslifkin]

Thanks Ted. I’m looking at a 6bt 210 with 6500 hrs. We might just get back in the trawler saddle.

The 6B Cummins series has a pretty good reputation for longevity relative to its power output and displacement. So I wouldn't be too concerned at 6500 hours. Check it out well (yourself or an engine survey) and if it comes up as healthy, it should have plenty of life left.

 

[Bmarler]

Thanks Ted. I’m looking at a 6bt 210 with 6500 hrs. We might just get back in the trawler saddle.

Glad to hear it. It was disappointing when you had to decommission the last boat.

 

[RT Firefly]

Greetings,
Mr. PM. GOOD TO SEE YOU BACK!!!!

 

[Tim]

Engine hours

My 1988 gb 42 with a single cat 3208na has 6200 hours with no oil burn and starts immediately cold or hot.

 

[RickyD]

I may not be the first to post this but beware the older boat with very few hours. Not used, probably not maintained regularly, probably hidden issues everywhere. My 1991 Californian 55 was beautiful when I bought her but had been used as a bedroom for a couple years. Lots of issues everywhere that would have been discovered if the owner really used the boat. Many were ticky tack some not so much. Water maker needed work, hey they never used it. Generators needed work, hey they never used them. Engines needed some minor stuff like heat exchangers even though the starboard engine had only 103 hours on a long block rebuild. I had about 1800 hours total on the starboard engine and 1900 on the port, probably because of the rebuild. Previous/previous owner indicated that the stb engine always ran hot until it didn't run. Way out of any warranty. I keep fixing stuff now in my fifth year of ownership, average cost of repairs, maintenance, and improvements, about $2,111 average per month. This includes some big stuff. 2x bottom paint. New bow thruster, new motor for davit, oil cooler for port engine, heat exchanger for port coolant, new canvas for fly bridge, all new Furuno nav gear, new battery chargers and six L16 house batts, six cutlass bearings, new exterior Naiad stabilizer seals. The list goes on and on. It does not include Bottom cleaning, wash/wax, slip fees, property taxes and stuff I forgot. Add those in and it just gets scary. And what is on the to do list? New carpets, new curtains, new canvas for sundeck, and anything else that crops it's ugly head. BUT----I love her.

 

[Circumnavigator]

There's only one mention above of oil analysis -- that's something that will tell you more than the hourmeter.


Several mentions above of the rating -- the Cat 3406 is (was?) available with ratings from 300hp up to well over 700. Although each higher rating came with more stringent rules about how often you could run it flat out, I would expect engines with lower ratings to last longer.


Jim

 

[UrsusMaritimus]

We have 4569/4581 on the Perkins 6.354s in our boat. They run like a top and we do an engine oil analysis at every oil change. Every time, the analysis looks basically the same. What will concern me is if it comes back markedly different. I don’t think I’m being overly optimistic to expect 10,000 plus out of these old engines.

 

[Alisske]

As an example, a Cummins 6B (natural 135 HP) could still be good with 20K hours.

A 6BT (turbo 210 HP) could be still good at 10K hours.

A 6BTA (turbo, after cooled 370 HP) might not last 5K hours.

Ted

Teds got it right. I would just add that i look at it from a HP/lb ratio. A 1500lb straight 6 lehman producing 120hp (NA) can basically outlive us all if maintained correctly.

Of course, condition, maintenance, etc… is just as important

I had a extremely well maintained Lehman 120 with 5000hours that I drove to Bermuda from Long Island. 5 days straight of 1800RPMs. Stopped each day for oil check.

Would do it again with that engine

 

[Capt Ray]

Getting engine oil LAB reports at every oil change is CHEAP... and like a blood test with your physician, it tells a LOT about what is going on. My engine oil LAB reports + my maintenance records will add thousands to my resale value.

Reportedly, CAT now uses "gallons of fuel" as their preferred metric over "engine hours" for scheduling oil changes and other major service intervals...

 

[cardinaltlee]

My experience working on thousands of aircraft engines indicates that the most important number is the frequency of usage. I have found that engines that run 100 hours a month will easily go past 5000 hours. The engines that average 5 hours a month seldom make it past a 1000 hours without major work. My very limited experience with boats seems to indicate that they work the same way. Run them at 60 percent power and run them a lot and they will last a lifetime.

 

[Mako]

Stopped each day for oil check.

Wow that’s something I would not do. I learned to measure oil level with the engine running. Even with twins.

 

[Art]

What's high hours on a 504 cummings diesel?

General comments on 504 cummings... when not too many hours and well cared for.

 

[cafesport]

If it’s rated for continuos duty 50k might not be unreasonable.

 

[Blissboat]

My experience working on thousands of aircraft engines indicates that the most important number is the frequency of usage. I have found that engines that run 100 hours a month will easily go past 5000 hours. The engines that average 5 hours a month seldom make it past a 1000 hours without major work. My very limited experience with boats seems to indicate that they work the same way.

That's certainly been true in my experience. Engines are built to run, not to sit. Quality engines in workboats are good examples, accumulating many thousands of hours with routine maintenance.

Any marine engine that is showing hours disproportionately low for its age has been sitting cold and still for a long time, and should be viewed with caution. The less information available about its history of use, the more caution.

 

[Art]

Quote:
Originally Posted by cardinaltlee View Post
My experience working on thousands of aircraft engines indicates that the most important number is the frequency of usage. I have found that engines that run 100 hours a month will easily go past 5000 hours. The engines that average 5 hours a month seldom make it past a 1000 hours without major work. My very limited experience with boats seems to indicate that they work the same way.

That's certainly been true in my experience. Engines are built to run, not to sit. Quality engines in workboats are good examples, accumulating many thousands of hours with routine maintenance.

Any marine engine that is showing hours disproportionately low for its age has been sitting cold and still for a long time, and should be viewed with caution. The less information available about its history of use, the more caution.

To a large extent I agree with the two quotes above.

However, there are other factors I've experienced regarding "gasoline" engine extended durability, during my over five decades of many road vehicles and boat ownerships.

1. Not too high RPM during ongoing use...
2. Torque not taken too much advantage of during accelerations...
3. Often lubrication fluid [oil] and filter replacements with the highest grades
4. Really good lubrication additives put into oil. Like ZDDP [for engines without catalytic converters]
5. Annual oil lubrication flushes [interior engine cleanouts] with Seafoam or extremely high-dissolve Berryman's B-12

All in all - Pronounced operator care also extends the life of engines... whether the engine is often or not too often used.

 

[ronobrien]

What do people feel are high engine hours on a 1985 350HP marine diesel?

People with 1980s engine feel free to give the HP, hours and how your engine is holding up?

BTW - I did a general google search and got answers from 5,000 to 15,000 hours. Of course the thing is hours tell nothing about how the engine was operated, just how long it was.

I worked in the service dept of a truck manufacturer (Mack) and we dealt with off road vehicles which ran up many more hours than miles. As an estimation for comparison we would use 30 statute miles for each hour of operation (actually hours in this case was counting revolutions, not time) . In the end, while hours are important, use and care are much more impactful, both in the positive and negative to an engine's condition and life expectation. Also running a diesel CONSISTENTLY below full load is not good. The piston rings use the cylinder pressure to seat against the cylinder walls. It is good to run them at full load for 5-10 minutes every time out. Edit: after running up to operating temperature of course.

 

[rslifkin]

I worked in the service dept of a truck manufacturer (Mack) and we dealt with off road vehicles which ran up many more hours than miles. As an estimation for comparison we would use 30 statute miles for each hour of operation (actually hours in this case was counting revolutions, not time) . In the end, while hours are important, use and care are much more impactful, both in the positive and negative to an engine's condition and life expectation. Also running a diesel CONSISTENTLY below full load is not good. The piston rings use the cylinder pressure to seat against the cylinder walls. It is good to run them at full load for 5-10 minutes every time out. Edit: after running up to operating temperature of course.

Pretty much any engine will benefit from at least a little time under moderately heavy load, even if it's in short bursts (such as in a car where you can't keep your foot down for very long). And in applications where it's possible, some time coasting down with the RPM held up in a lower gear is beneficial for keeping the rings moving freely, especially on gas engines where they're throttled and build vacuum in that situation.

Generally with the boat, once we've run a handful of hours at slow cruise (which for us is 1250 - 1300 rpm with the throttles barely cracked open), I pop it up on plane for 5 - 10 minutes to get some good load on the engines. Get some pressure on the rings and get everything good and hot (oil, spark plugs, etc.).