High Hours and Service Life?

[harborlights]

I have seen some large diesels in boats with 60k-100k hours on the engine. What kind of service is required to rack up so many hours? Does that hourage mean the original block is still in service?

[hellosailor]

What's "large" mean? I'm thinking, like a locomotive engine. That's a "large" diesel to me.

But regardless of size it typically means change the oil on schedule, don't abuse the engine by overheating or excess idling, and do the normal mainenance. Which in some engines, even in regular tractor trailer engines, can mean a teardown every half million miles or so followed by a complete rebuild.

All depends on what you've got and what it allows for. Really "industrial" engines will have replaceable cylinder liners, so you can reline them instead of boring out the cylinder walls.

[Sailmonkey]

What is large?



To me, this is large and should last over 200000 hours with regular service.

[harborlights]

I thought a Detroit Diesel 12v71 was a large diesel which would need to be rebuilt ~20,000 hours. That's a lot of overhauls. I figured the block would warp after the first or second overhaul.

[spearfish3]

Originally Posted by harborlights

I thought a Detroit Diesel 12v71 was a large diesel which would need to be rebuilt ~20,000 hours. That's a lot of overhauls. I figured the block would warp after the first or second overhaul.

Turbo charged Detroit Diesels were lower hour engines between rebuilds but they could be rebuilt in the boat. They were and still are popular with charter boats for that reason. Naturally aspirated versions would go a long time, maybe even to the 20k hour range.

Lugger and John Deere Diesels in trawlers can go to the 20k hour mark before an overhaul and I would not be surprised if some went longer.

My dad was in the mining business and would have Cummins and Cat engines routinely hit 12-15k hours between overhauls. He liked the Cat 3406 and Cummins KT1150 engines. My favorite was a 3508 that was in a dragline that I was an oiler on one summer. It was slow turning and sounded like a locomotive.

I think you will find that most extremely long lived engines are slow turning and very large displacement. The ships engine above is a great example. In more normal applications, you are looking at duty cycle engines that significantly derated from the standard marine configuration. If you put 20k hours on a boat, you will have had a lifetime of memories.

[harborlights]

Originally Posted by spearfish3

Turbo charged Detroit Diesels were lower hour engines between rebuilds but they could be rebuilt in the boat. They were and still are popular with charter boats for that reason. Naturally aspirated versions would go a long time, maybe even to the 20k hour range.

Lugger and John Deere Diesels in trawlers can go to the 20k hour mark before an overhaul and I would not be surprised if some went longer.

My dad was in the mining business and would have Cummins and Cat engines routinely hit 12-15k hours between overhauls. He liked the Cat 3406 and Cummins KT1150 engines. My favorite was a 3508 that was in a dragline that I was an oiler on one summer. It was slow turning and sounded like a locomotive.


I think you will find that most extremely long lived engines are slow turning and very large displacement. The ships engine above is a great example. In more normal applications, you are looking at duty cycle engines that significantly derated from the standard marine configuration. If you put 20k hours on a boat, you will have had a lifetime of memories.

The engineering is fascinating stuff. I'm a young guy just getting into this stuff so it's a little confusing. How could someone rebuild an old Detroit 4 or 5 times without boring too much of the cylinders away in the boat? Are the John Deeres better engines?

[Sailmonkey]

Originally Posted by harborlights

The engineering is fascinating stuff. I'm a young guy just getting into this stuff so it's a little confusing. How could someone rebuild an old Detroit 4 or 5 times without boring too much of the cylinders away in the boat? Are the John Deeres better engines?

Two words.

Wet liners

[a64pilot]

Big motors can last indefinitely as everything is replaceable.
I recently learned that my little 4JHE has wet liners, but they aren’t replaceable. I knew it had wet liners and assumed like all others that they were replaceable, but I guess not.
Wet liners are one hallmark of a “true” industrial type of Diesel to me.
I always did “in frame” overhauls of backhoes and tractors, cause it seems if you kept the oil changed every 100 hours the crank and cam never wore out and the main and rod bearing are easily changed, that with new pistons and rings and overhaul the head and fuel system, and you have a new engine.

[Nicholson58]

Originally Posted by Sailmonkey

What is large?

Attachment 175441

To me, this is large and should last over 200000 hours with regular service.

Holly smokes! That’s my diesel!

Our Westerbeke is 115 HP 6 cyl 1984 with lots of thousands of hours. It was a repurposed British Layland tractor engine. Really beafy and physically huge, 1000 rpm. I have a Franz 1 micron bypass crankcase filter so the oil stays really clean. We change oil when the viscosity drops. This engine starts instantly and puts along faultlessly.

[harborlights]

Originally Posted by a64pilot

Big motors can last indefinitely as everything is replaceable.
I recently learned that my little 4JHE has wet liners, but they aren’t replaceable. I knew it had wet liners and assumed like all others that they were replaceable, but I guess not.
Wet liners are one hallmark of a “true” industrial type of Diesel to me.
I always did “in frame” overhauls of backhoes and tractors, cause it seems if you kept the oil changed every 100 hours the crank and cam never wore out and the main and rod bearing are easily changed, that with new pistons and rings and overhaul the head and fuel system, and you have a new engine.

There could really be one day a Detroit with 150,000 hours on it because you can replace everything? What happens to the block after 7 or 8 rebuilds?

[a64pilot]

Why would anything happen to the block, unless it’s way overheated or something large and heavy dropped on it or something.
Even if something happened, replace it.

[harborlights]

Originally Posted by a64pilot

Why would anything happen to the block, unless it’s way overheated or something large and heavy dropped on it or something.
Even if something happened, replace it.

I don't know. I guess I thought most blocks would be warped by then.

[a64pilot]

Nothing to warp them, actually there seems to be quite some evidence that a block that has gone through thousands of temp cycles etc. is “seasoned” and stronger than a new one.

[Lepke]

Large engines with 100,000 hours have had the bearings and liners changed, probably several times. The block maybe several castings, either welded or bolted together. Heads usually only cover 1-2 cylinders. Crankshafts that haven't seen oil loss are still usually standard when the engine is scrapped. Continuous duty engines have bigger crank journals, wider bearings and better cooling. The oil in the pan is circulated out of the engine thru a cooler and filters and then back to a pressure pump. Normally the oil is heated before starting, causing less wear. Often pressure is applied before starting, too. A number of studies have shown most engine wear occurs at startup. Many ship and tugboat engines run 24/7 and the oil is changed while running. Fresh oil is drawn by the pressure pump and existing oil goes to a waste oil tank until it runs clean. Later the waste oil is filtered and added to diesel and burned as fuel.

Detroit Diesels are very reliable diesels and the basic design happened in the 1930s. They don't have an injector pump, so no bleeding issues. Injector is mechanical and contains a plunger that makes necessary pressure. They have sleeves in the cylinders, so after overhaul the engine has same as new performance. If a turbo Detroit is pushed really hard, heat will cause areas in the water jacket to swell. When that happens the cylinder has to be bored and an oversize liner used. Normal life for a high hp turbo Detroit is about 3-5000 hours. A good operator will get 7000. I got 10,000 on engines I owned, but kept the oil clean and the hp down unless necessary. Natural Detroit engines routinely go 20,000 hours. Some are never overhauled in their life.
An independent log truck owner I know, with a Cat 4106, runs a million miles between overhauls. Cat has left the truck new engine market and is concentrating on marine and industrial engines.

[model 10]

Originally Posted by a64pilot

Nothing to warp them, actually there seems to be quite some evidence that a block that has gone through thousands of temp cycles etc. is “seasoned” and stronger than a new one.

Yes, BMW built 1200hp F-1 engines with old cast iron blocks.