Life expectancy?

Also trying this over at boatdiesel, but no love so far, so hoping for at least some anecdotes here.

I am under contract awaiting survey on a vessel with a pairs of JD 6081AFMs. These come in four versions using JD rating system from M1 to M4 with horsepower range from 235 to 376. These are the M2 versions at 300 HP. They are turbocharged/aftercooled engines and currently reading in the mid 5000 hour range.

I am aware there is no way to know on a specific engine, but I am looking for any experience indicating a 'normal' service life to first overhaul.

Comparing the hour meters and the logs suggests that this vessel averaged 10.6 knots over its life so far. (I know, average tells me nothing about extremes) On the curves that would indicate an average of 1100 rpm these 2400 rpm engines. It would also suggest that on average again, they have burned around 15000 gallons each. Displacement is 8.1 L.
The original owner that had her built is an engineer and seems pretty particular at that.
Useful to keep in mind that this is in a passage making configuration and not a sportfish in terms of thinking about how it might have been run for loading.

So for the guru out there or anyone with direct experience with this powertrain, what say you about where these are along the path to a major? If these were NA engines I may be less concerned?

Thanks in advance for any wisdom here.









https://xanthiona.files.wordpress.com/2010/02/6081afm75_d_s0_r0.pdf

Using Detroit Diesel twin turbo, running hard but careful with clean oil, I got about 7000+ hours. Running at 80% of hp or less, about 11,000+ hours. Running 100kw+ generators with Detroits @1200 rpm, decades. No long experience with JD.

At full load that is 37HP /L .Your data indicates much lower average load maybe 20 Hp /L at that level they will never wear out with proper installation and maintenance.

bayview said:

At full load that is 37HP /L .Your data indicates much lower average load maybe 20 Hp /L at that level they will never wear out with proper installation and maintenance.

Click to expand...

I would add proper operation to the installation and maintenance above.

David

Those engines were very common in generators were they ran from 20,000 to 30,000 hours between over hauls.

If they have maintenance records to spec-then just nicely broken in. Turbos may be coming up for service/replacement.
As a comp. CAT expects 50,000 gal. Life expectancy for 3208 TA. Probably yours would be in a similar life expectancy range.

Might be worth a call to several JD rebuilders. My guess is that they can atleast give you the book ratings for the different M values. As an example, my 4045 with an M1 rating is 10,000 hours at I believe 80% continuous duty. I have the M3 rating which is only different in the computer programming. I wasn't willing to spend $800 to reprogram it to M1. My use is far below M1, so I'm expecting 20,000+ hours to the first overhaul.

Would also be nice to have current pricing on a complete rebuild.

Ted

O C Diver said:

Might be worth a call to several JD rebuilders. My guess is that they can atleast give you the book ratings for the different M values. As an example, my 4045 with an M1 rating is 10,000 hours at I believe 80% continuous duty. I have the M3 rating which is only different in the computer programming. I wasn't willing to spend $800 to reprogram it to M1. My use is far below M1, so I'm expecting 20,000+ hours to the first overhaul.

Would also be nice to have current pricing on a complete rebuild.

Ted

Click to expand...

The spec and loading characteristics are easy to find. They are at this link I included in post#1.
https://xanthiona.files.wordpress.com/2010/02/6081afm75_d_s0_r0.pdf

Best information I can find from rebuilders is 15K per side for all materials including turbos, coolers etc. but harder to estimate labor since these are each in one of the ama and I have yet to determine how they come out of there. Perhaps not surprisingly, a rebuilt long block drop in can be had easily for that same amount.
Based on a range of feedback, I sort of feel like these are around 1/3 thru a reasonable interval to first overhaul if they were treated decent. That will not happen in my lifetime. I do not cruise anything like the original owner. That dude had some serious ambitions and executed them. Inspiring for sure, just not me. I could not put on them in thirty years what he put on them in ten.

Bill,

I have something for you. I'm religious about oil changes and oil analysis. Was trying to get to the manufacturer's recommendation for oil change hours, but wear metals started rising. Keep in mind that I'm cruising the engine at approximately 40 HP, 2 GPH. This from an engine with 135 HP and almost 7 GPH fuel consumption rating. I discussed it with my JD dealer who is old school, and only does oil analysis when there's a problem. He contacted JD and they sent him an internal document for wear metals for all their engines. The amount of wear metal is breathtaking for an engine used in commercial applications (generators, farming, logging, etc.) with the 10,000 hour rating. My takeaway was that my engine life expectancy based on wear metals should be substantially higher. I also reduced the oil change interval rationalizing that a <$60 oil change was nothing compared to the rebuild cost and hassle of removing the engine.

If you would like a copy of the document, PM me an email address, and I'll get it to you on Tuesday when I get home.

Ted

Many engine manufacturers are moving away from hour based major overhauls and are moving toward total fuel burn. It’s a better indicator of life and can account for a wide variety of operating history eg many hours at low rpm/load to fewer hours at high rpm/load.

If you can make a good estimate of total fuel burn it may be worth talking to JD about whether they have any recommendations based on that.

We have a JD 4045 like Ted. The JD 4045 can be rebuilt in the boat. I read that it can be done in a day. Some quick searches indicate rebuild kits are quite reasonable. With a spare cylinder head and the accessories, I don’t think it would be a huge undertaking for a certified and professional JD tech...maybe 2 days.

It appears the 6081 may also be rebuilt in the same fashion.

I hope to get 20-30K out of ours. It will be difficult to put that time on, but we will try.

I look forward to learning about your new boat, presuming she passes muster. You own some interesting and substantial vessels...

Echoing Irene, that engine can easily be rebuilt. Access is the key as to the cost and timing for that effort.

A read of the maintenance log would offer some clues as to ongoing routine servicing being good bad or indifferent. She may be approaching time for a by the book total servicing no matter what the logs say. JD has a good list in their manual.

A weak spot on some JDs is the raw water pump. If original I'd throw them away and go with new ones. A complete removal and cleaning of the after cooler and heat exchangers should be done too as well as hose replacement. Why? These remiss maintenance areas are potential overheat items that cause premature wear thus advancing re-build time.

Bore scoping the engines is easy enough to do and along with knowing oil consumption could add some information. But quite honestly, if run and maintained right to 5,000 hours you're with many years in front of you on those 6081s.

Two questions- what boat and what year?

I would expect no less than 20k hours, and would be celebrating if I got more than 40k. 5k is no concern at all assuming to usual checks all pass.

Only slightly relevant. I got 24,000 hours out of an Isuzu engine over 10 years. The engine was not worked very hard but we also only got around to changing the oil once a year. I think calendar years is more the enemy than hours for diesels in the yachting world. This assumes you do proper maintenance.

sunchaser said:

Echoing Irene, that engine can easily be rebuilt. Access is the key as to the cost and timing for that effort.

Two questions- what boat and what year?

Click to expand...

First, the life expectancy thing. Ironically, I have owned an operated many of this 8.1 liter JD on dry land and consider it one of the best configurations JD has ever produced. It is one of the many reasons this boat caught my eye for sure. We have gone over 30K on many of them. But, I am a bit jaded on marine anything. The reliability and durability of marine equipment has just not measured up to equipment we operate on dry land in the same hands and technical support locally seems much tougher in terms of skill sets and availability.

Now, the boat...
I cannot actually name the boat before closing though a member here has figured it out already. Two reasons, one is that would just be bad juju before we close and two is that I will immediately need to resign my TF membership when the reveal happens as this crowd will revolt.
I can offer a tease though: It is a true passage maker as defined by Beebe and is, in fact, featured in the fourth edition, and has also been featured in the magazine with the moniker. It has three Transpacs under her belt and sports 45 courtesy flags. Its prismatic coefficient should be the envy of anything owned by any member here resulting in remarkable efficiency and a range of 6000 NM. Her designer is beyond reproach.
Thursday is the big day and acceptance must happen by Friday if it is going to happen. This whole thing is well out of what I would have considered my comfort range but I am quite excited and looking forward to learning about a whole new maritime experience. If we close, I will be looking forward to a 2200 NM delivery over some of the most exciting waters the world has to offer. Life is good.
Anybody need a boat? I may be one over my quota by weeks end!

Little update here.
Survey and sea trial of these engines today was real solid. Thermal imaging, exhaust gases, ability to reach rated rpm , speed trial, pressures, cooling, etc under all loads was at or above spec.
If I was looking for a reason to come to my senses, this ain't going to be it.

Fuel use as indicated by the ECM over a range of speeds was something that I could never have imagined in my previous life. While we all admit that fuel use is not the most significant consumer of funds in our kind of boating, it is still very cool to think about what engineers and architects have achieved in this vessel.

Steve Zimmerman posted a great article in PassageMaker maybe a year or two ago. Contact the magazine or Steve to find out about that article. It delved into Commercial and Recreational uses and engine ratings, if I remember correctly. Great stuff - as usual from Steve.

NCheaven said:

Steve Zimmerman posted a great article in PassageMaker maybe a year or two ago. Contact the magazine or Steve to find out about that article. It delved into Commercial and Recreational uses and engine ratings, if I remember correctly. Great stuff - as usual from Steve.

Click to expand...

Found it. Useful. Thank you. January of 2019.

https://www.passagemaker.com/technical/how-long-will-my-engine-last

life expectancy

klee wyck said:

Also trying this over at boatdiesel, but no love so far, so hoping for at least some anecdotes here.

I am under contract awaiting survey on a vessel with a pairs of JD 6081AFMs. These come in four versions using JD rating system from M1 to M4 with horsepower range from 235 to 376. These are the M2 versions at 300 HP. They are turbocharged/aftercooled engines and currently reading in the mid 5000 hour range.

I am aware there is no way to know on a specific engine, but I am looking for any experience indicating a 'normal' service life to first overhaul.

Comparing the hour meters and the logs suggests that this vessel averaged 10.6 knots over its life so far. (I know, average tells me nothing about extremes) On the curves that would indicate an average of 1100 rpm these 2400 rpm engines. It would also suggest that on average again, they have burned around 15000 gallons each. Displacement is 8.1 L.
The original owner that had her built is an engineer and seems pretty particular at that.
Useful to keep in mind that this is in a passage making configuration and not a sportfish in terms of thinking about how it might have been run for loading.

So for the guru out there or anyone with direct experience with this powertrain, what say you about where these are along the path to a major? If these were NA engines I may be less concerned?

Thanks in advance for any wisdom here.









https://xanthiona.files.wordpress.com/2010/02/6081afm75_d_s0_r0.pdf

Click to expand...

I have a 1984 Ford Lehman with 7600 hrs that runs quite well. It's been well maintained and while it's required some repairs here and there it has held up well. A well maintained and properly operated FL 120 should last for 10,000 hrs before needing a major rebuild or overhaul.
Sorry, I don't know anything about your engines but maybe this will give you an idea. Good luck.