Highest engine hours without rebuild???

my 2 cents

OK, Guys...just thought i'd throw my 2 cents in here......as a CAT specialist, an ASE certified Diesel technician, and a General Motors Master technician, i think i have a little insight on this subject......(although, i'm gonna need some help with bottom painting!!!!!)...Diesel engines will run as long as they are maintained.....i have seen 3126 CATs with well over a million miles on them...so you figure that's 166 hours for every 10,000 miles(at 60 MPH)....and i have also seen them blow up with 30,000 miles......a school bus that is stop and go will eat a motor in 30,000 miles....a Peterbilt might go 800,000 or more before an in-frame overhaul, just because it spends most of it's time around 2500 RPM.....so, in my humble opinion, it is better to run your diesels at a higher RPM and for longer periods if you want longevety......BTW on the line boring thing...if tolerances are ok, lione boring is not needed...when we do in frames on the big diesels, we put new rod and main bearings, new pistons, new cyl sleevesand have the heads worked...skip any of this stuff, you are wasting your money....BTTW the Hercules MCL's in my roamer were dead at 660 hrs....go figure!....

1946 hours Chrysler 318 engines

I have a pair of Chrysler 318 engines with 1946 hours on them, and they run perfectly! same owner last 17 years, boat was hauled out every winter, engines were always maintained properly. they start and run like brand new, and feel like they have a lot of life left in them!

Hi,

I like the reasoning but am afraid it is one of those things that works out well mathematically but doesn't generally play out so well in reality.

How many cars are run the same 7 days a week?

Cars don't generally don't breathe salt laden air or sit with their exhaust valves open and have a salt atmosphere drawn in by convection.

This is the biggest killer. I've seen marine diesels have dead cylinders and needing majors with as little as 600hrs from sitting on a waterway with a lot of current, and not being run often enough and the salt air corroded liners and valves/seats. Not enough use is a big killer also.

I've also seen marine diesels live a very short life because the engine room air boxes weren't adequate in airflow, or allowed way too much salt air/water into the engine room which was ingested by the engines.

Also each engine has a lifespan, some a lot more than others.....due to Rpm range, or HP rating.

Cummins 555

Many years ago I worked on an old sportsfisher that had 555 NA's. The engines had 27,000 hours on them and apart from normal routine maintenance they had never had a spanner put on them. The owner decided after so many years to have Cummins replace the injectors with exchanges. One of the replacements had a cracked cup which ended with oil dilution which resulted in a total rebuild. The owner being fastidious rebuilt the other at the same time. I guess if left alone, those engines would have easily gone over the 30,000 hours. Incidentally those engines are currently approaching 13,000 hours since the rebuild again with minimalistic maintenance on them. A lot to be said for the manufacturer.

Eats at them, but typically the motor wears out far before the salt does anything detrimental. Except maybe a circulating water pump or something. I know of someone that just rebuilt a saltwater cooled 26 year old 351W. It's preferable to have raw water cooling, but then you get into the expense of heat exchangers etc etc.....cleaning them.....etc.....etc..... in the long run, it may be cheaper to just go raw water and replace when worn out.....this is a different issue when you're talking about hard to replace engines such as 427's and stuff found in some of these chris crafts.....

Hi,

You better offer them to Cummins as museum pieces.

That was one of the worst engines ever built, to read of such a fantastic life-cycle is certainly refreshing.

I know of a few older Trojan internationals with 454 Crusaders that have only had tune ups and oil changes with over 3500-4000 hours on them and still run and compression check with no issues.

A friend if mine has a Sea Ray amberjack with 3800 un touched hours on it and the boat is run hard in fishing tournaments, he's been planning for a repower but each year the boat runs perfect!

Total Hours vs. running hard

I was going to post this as a new thread but let me pick up a line of thought here regarding how hard you run the motors. I am specifically talking about DD's either 871's or 1271's on a 1973 55' ALum ROamer and 1968 60' FG Commander respectively. My understanding is at low RPM's (1200 or lower? fill in the blank) you get incomplete combustion, low heat generation, and washdown of the oil on cylinder walls from the diesel, thus causing premature wear. Now, what is the risk when running them hard (2100 RPM or higher, fill in the blank for redline) for extended periods of time, say 2-3 hrs at a time? Besides burning a HUGE hole in your wallet with their thirst, I hear alot of comments on how the DD's are bullet proof and the allison tranny its mated to is also bullet proof. What is, and how high is, the risk of catastrophic failure in running them hard for a few hours? Were these motors not originally made to run at highway speeds for hours on end?

Mahalo

I recall that the South Ferry out of Shelter Island, New York had 69,000 hours on their Series 60 engines and that was in 2009. Nothing like a repetitive ferry route to build up long hours, as you can dial-in the speeds for the operation - a brief amount of Idle an then right up to 80% throttle and do it all over again and again.....

Hi,

I remember reading a report on a Series 60 that was in a truck operated by JB Hunt from Alabama and it had done 1,000,000 miles when stripped.

Nearly everything except the crank brgs were good for further use.

Not a bad effort.

That's not exactly good either. The Exhaust temps heat up for a short period of time, cool down to idle, then heated right back up and back and forth.....some expansion and contraction.

2100's is a little hard, less hard if they're Naturals.......2000rpms would be ok......but if the boat only stays on plane at 2100, then run them there. Keep a real good eye on your water temp if you do......And it depends, if they're propped where they achieve more than rated RPM's at WOT it's less hard on them. You do get incomplete combustion under 1200, but to various degrees depending on injectors, engine temp, etc......I've run lots of engines at 1000 rpms for long periods with no ill effects. With Detroits, I'll run them 4-6hrs (generally 6), then run them up to 1300rpms until the soot bakes off (about 3 minutes) then bring them up to 1950rpms for 25 mins......then back down to 1000.......

Well, it was good enough for at least 65,000+ hours!

This particular run is very short, 1/2 mile or so, and there are more factors at play than just exhaust temps. An efficient vessel design, the right loading of an engine selected at the right duty cycle, clean lube oil, good fuel and plenty of intake/exhaust air, efficient raw water piping layouts a captain with a good "throttle-hand", etc.

With Southside, South Ferry finishes fleet overhaul

Surviving the leaking defective aftercoolers a lot of Series 60 came with. The amount of hours is remarkable, no doubt. There are also a lot of factors that go into that long life as you've mentioned......Cat, rates their engines lifespan in both hours or fuel consumed......I wonder what the engine computer stated for lifetime fuel consumed, when those motors were rebuilt.

OTO, all it takes is one overheat situation on a good diesel and you need a rebuild sometimes.......