High Hours and Service Life?

[harborlights]

Originally Posted by Ecos

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

For real? o_o

[a64pilot]

Originally Posted by Ecos

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

I didn’t know that

[oleman]

The USN LST class of ship was powered by 4 General Motors (EMD) Large diesel Engines, basically re-purposed from the GM locomotive industry. It was very rare that any engine was ever totally removed in the life of the ship. Cylinders could be removed individually for repairs. The ship had two screws with two engines in parallel on each screw. Totally mechanical system. Engines were about 3000 HP each, could keep up with a slow USN task force and reliability was not an issue.

[nhschneider]

Originally Posted by Sailmonkey

Two words.

Wet liners

Minor correction: The Detroit 53, 71 and 149 series used dry liners.

Fair winds and calm seas.

[SouthernPride]

1973 Hatteras 53'
2 8V71N diesel engines.
Average 300 to 400 hours a year.
oil changes, wet liners, and I use air conditioning, blowers to keep cool.
No problems as of today.

[jacktheflyer]

Originally Posted by harborlights

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?

You can get some fretting at the base of the liners and the seals leak water into the sump. I've had engines go 75,000 hrs between overhauls. I was party to the second overhaul on these (White Superior V16 about 800hp). Key is low stress lo revving and continuous running to achieve these hours. I've also had Cat 3406 go 45,000 hrs between overhauls.

Scrubby

[steveinusa]

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?

Replaceable steel liners as the cylinder walls. Instead of boring out the cylinder you just replace the liners.

[a64pilot]

Originally Posted by jacktheflyer

You can get some fretting at the base of the liners and the seals leak water into the sump. I've had engines go 75,000 hrs between overhauls. I was party to the second overhaul on these (White Superior V16 about 800hp). Key is low stress lo revving and continuous running to achieve these hours. I've also had Cat 3406 go 45,000 hrs between overhauls.



Scrubby

So, just out of curiosity, how do you explain what everyone here seems to take as Gospel, that is you have to run a Diesel hard, as in 80% or more of its available RPM for one to last?

[john61ct]

The issue I believe is temperature, too low is no good.

An underloaded diesel is just fine as long as it is run hot for a while every so often.

[Cheechako]

Engines that run 24/7 last for more hours. Also, commercial engines are rated at lower rpms for "continuous duty". For intermittent recreational use the same engine may be rated at higher rpms. Lower rpms = longer life.

[model 10]

Originally Posted by a64pilot

I didn’t know that

There is a story about those old 4 cylinder cast iron blocks BMW collected. They were in a pile outside the race shop and guys would piss on them, part of the aging process

[sy_gilana]

Dont want to jinx anything but.


Our Onan MDJE generator from 1978 has nearly 30,000 hours.

Our Detroit 3/53 is at 4500 hours, also a 1978 model.


Neither have had a major o/h.



Religious servicing, pamper and care, a labor of love.

[hellosailor]

"So, just out of curiosity, how do you explain what everyone here seems to take as Gospel, that is you have to run a Diesel hard, as in 80% or more of its available RPM for one to last?"
Combustion engineering IS rocket science. Consider this, in order to find out what is happening in an engine, you need to somehow measure or look INSIDE the combustion chamber while combustion is going on. Right, how do you look inside a chamber where there may be a 1000 degree explosion happening hundreds of time per minute, without disrupting that process?
It was considered a great break-through when someone figured out how to install a quartz observation window in engine cylinder walls, literally allowing direct observation of the flame front with "minimal" disruption of the process. (Since the window changes cylinder wall contact, changes wear, changes the flame front, all to some extent.)

SO a lot of what goes on, and how it goes on, has still been changing. One point being Honda's improvements in the last 20 years, creating turbulence for a "swirling" fuel mixture and more thorough combustion, giving more power and a cleaner burn. Somehow everyone had missed that for a hundred years. And overlapping intake and exhaust valve openings, to encourage better flow of the intake charge and scavenging of the exhaust gas--which had previously been anathema, everyone figured that would lose power.
And then you need the financial resources to run that kind of test engine, and perhaps out 100,000 hours on it. Repeatedly, maybe across a dozen engines, for each variation you want to test. The phrase "deep pockets" comes to mind.

But on a64's question, decades of fleet service reports and warranty analysis all indicated that on diesel engines, if you don't run them hard, you get incomplete combustion and then hard carbon deposits formed on valves and valve seats and in exhaust elbows, and those carbon deposits would cause problems. You'd also get more cylinder wall damage. Running the engines at 80% (whatever) was supposed to put enough pressure on the piston rings to scrape the walls clean, make a cleaner fuel burn, and expel the particles better. It was all supposedly documented.
Was. Because diesel manufacturers using the "new" diesel engines (whatever that means) in cars and trucks and larger installations, now often claim this no longer applies. Exactly why, I don't know. I haven't had access to a combustion engineer in a long time--and they're they only ones who really get paid to learn the answers to this stuff.

On the question of how many rebuilds? Depends totally on the engine and maker. If they put enough "meat" around the cylinder walls, and you overbore them gently enough, you can overbore 4-6x without a problem. That is, IF someone also supplies oversized pistons and rings to fit the larger hole. Or, as noted, if the engine maker uses cast iron inserts. Caterpillar, GM, Peugot (!) have all been known to do that. Peugot used to use replaceable cylinder walls that were individually gasketed, with the gaskets prone to fail. Ooopsie. GM & Cat? Some engines are designed so a crew can go underneath the engine and drop an individual liner that way. (On what some of us would call huge engines.)

Very few recreational owners are going to do their homework and look into these things ahead of time. Fleet operators, steamship owners, railway barons...they're the ones who tend to worry about all this more.

[Cheechako]

One question may be "is the wear from stopping and restarting an engine worse than leaving it idle?" Truckers idle for many hours sometimes.

[a64pilot]

Originally Posted by Cheechako

One question may be "is the wear from stopping and restarting an engine worse than leaving it idle?" Truckers idle for many hours sometimes.

Back in the 70’s when high bypass filters and synthetic oil became the rage, many were also fitting pre-lubers. Either a pump, but usually a pressure accumulator and solenoid that would supply pressurized oil through the engine before starter engagement.
Some aircraft engines have had pre lubrication for well since WWII I guess, big old radials that had to have it, cause you may have 9 cylinders all running one one rod bearing, usually rows of seven though.
Anyway in the truck and automotive world turns out it didn’t make any measurable difference, so you don’t see them anymore.

Trucks used to idle almost every night to run the AC etc, now due to emissions they have what they call APUs, just generators but they don’t idle so much and in many places it’s illegal to do so.
However my theory on why it wasn’t bad for them is that you didn’t idle all night, get up in the morning and shut it down, you got back on the road and ran it for a decent time.