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ktdtx 01-03-2015 11:29 AM

Engine(s)-part of locating the "Right Boat"
I am still in the process of looking for our "right boat".
Mission is to cruise the PNW including Inside Passage. Looking at 45'-55' pilothouse type-single or twin engines.
Part of my process is evaluating the engines for desirability, reliability, cost of operation and so forth. I consider myself a little short on first hand knowledge.
I understand that a lot of how an engine in a used boat will perform is based on how it was previously used and maintained.
My shopping, talking and poking around the internet have led me to some general thoughts and would like some feedback to see how close to correct I might be. I also realize there are a lot of opinions involved here and most will be better than mine.

These are generalities:

Lugger/John Deere-desirable engines-reliable, economical

Cummins VT-555 parts expensive and difficult to get
Cummins 6BT and 6CT-good engines, run well
Cummins Q series-newer, good-can run slow for economy w/o a problem

Caterpillar 3208 Good, reliable-better with less HP squeezed out
Cat 31xx series not highly desirable
Cat C Series-newer, similar thoughts to Cummins Q

Detroit x-53, x-71 are repairable, rebuildable, reliable but a little loud and a little messy. Better the less HP you squeeze out.

Detroit DDEC-avoid--less reliable parts availablity difficult

Detroit 4 stroke diesel--don't know but not many there

MAN-a lot in some Bayliners/Meridians--don't know

Volvo-don't know

I forgot these:
Lehman-the 120 & 135-economical, reliable and parts available

Perkins-reliable, some better than others


MYTraveler 01-03-2015 11:45 AM

QSM11 in the 450hp config if you don't need more power.

hmason 01-03-2015 11:57 AM

We have the much maligned Cat 3116s in our GB 46. You can research these engines to the point of exhaustion and what you will find is that the blocks that were made in France had issues. Those engines failed within the first 500 hours. The engine serial numbers will tell you if the blocks were made in France.

We are approaching 4,000 hours on our twin 3116 turbos. They are economical, smooth as silk, and have not had a single issue to deal with. If you eliminate boats with these engines, you will eliminate many really good boats.


ktdtx 01-03-2015 12:01 PM

Thanks--just what I'm looking for, first hand knowledge rather than the always present "common knowledge" that "they" said.


sunchaser 01-03-2015 12:05 PM

Forget about brand when looking at 4 strokes. As you stated, think PO's care and diligence. Here are a few engine things to look for
  • Are spare parts readily available such as coolant and RW pumps, HXs, turbos, transmissions and fuel system pieces.
  • Timing for RW pump impeller, fuel filters and oil change outs.
  • Decent records
  • Spotless is good, clean bilges and no rust on water or fuel tanks tops.
  • Is the boat propped right
Once you have gotten through the PO's attentiveness then start flipping coins between JD, Lehman, Perkins, Cummins, Cat or Lugger for those below say 350HP. When going above 350 HP the things to look our for get very engine specific because within brands there are some goods and bads and MTU and MAN enter the mix.

Boatdiesel is your engine website friend, pay the $25 and do some real searching.

Ski in NC 01-03-2015 12:42 PM

Second Hmason on the 3116/3126: These engines in trawler service do very well. In sportfish and fast boat applications where run at high power settings, they have had problems. Don't buy one that has been run hard. I find them to be some of the nicest running engines out there. And some boats are discounted due to these engines.

I run a Cummins 6CTA 450, it is 15yr old and abt 3000hrs, been flawless. 6BT, 6BTA also have a very good rep and are everywhere. But not that common in trawlers.

Any Cummins with a Q prefix is an electronic engine. The electronics spooked us at first, but have proven to be quite reliable.

3208 rated at 375hp or less, very good engine.

C-series cats are like the Q-cummins, electronic. Generally good.

Volvos and Yanmars and MAN and MTU- good engines but parts prices will kill you. Also some head scratching design features that drive you nuts. All engines have things like that, but just fewer on Cat and Cummins.

John Deere, Lugger- good stuff. Just not that many examples in my area to report on.

djmarchand 01-03-2015 12:49 PM

Well, I think that your list is mostly in the ballpark with some exceptions:

* I wouldn't touch a DD 4-53 unless it was in a Hatteras LRC.

* As one poster said the problems with the Cat 3116 have been Darwined out, so I wouldn't turn my nose up at any of the Cat 3xxx engines.

* I might consider a pair of DD 8.2 4 cycles if the boat were otherwise a great deal and suited my needs to a T. Sort of like the Hatteras LRC above.

* Budgetary considerations will probably limit consideration of newer Cummins Q engines or Cat C's. I doubt if you will find many boats with a pair of those for less than $500K.

* For some reason you don't see many Volvo engines in the boats that you are interested in. But I wouldn't turn my nose up at any of the D engines. Even more so for the Yanmars, although you might find the big Scania based engines in some.

And don't get too hung up on fuel consumption. The difference between the best and the worst is only a few thousand dollars when going 8 kts along the entire round trip inside passage in a 50+' trawler.

But I think that for the mission you describe- inside passage, I would be most interested in ultimate reliability. In that case the condition of the specific vessel is most important, the color of the engine second. But I would look at what the local fishermen use.


sunchaser 01-03-2015 12:55 PM


Once you have narrowed some things down, I'd suggest you use Ski to do some major sleuthing and or survey work for you. He knows his stuff and does it for a living. Whereas all too many of us are weekend warriors with bruised knuckles.

Marin 01-03-2015 09:15 PM

Ken--- It's unlikely that you'll find Ford Lehman 120s, or even 135s in the sizes of boats you say you're interested in. But since you included them on your list.....

I'm not a fan of the FL120 for several reasons, even though the boat we've had for the last 16 years has a pair of them. If they have been operated and maintained properly--- and this is really important with these engines, particularly the "operated" part---- they have a reputation for going a long time between major overhauls. The number I have been given by people with a huge amount of knowledge and experience with these engines is 12,000 - 14,000 hours in recreational boat service. (Even longer in commercial service).

However, to get that kind of longevity, they need to be operated in a fairly conservative power band. As described to me by acquaintances in the UK with a long and intimate relationship with these engines, this band is 1500 to 1800 rpm. We operate at 1650. In the 16 years we've had this boat the engines have been over 1800 rpm exactly once, and that was to get rpm data for the prop shop.

The reliability and longevity of an engine is totally dependent upon how it was operated and maintained. While we have had excellent service so far from our FL120s, we were very, very lucky with regards to the boat's previous owners.

We would never again buy a boat with these engines. Besides being way too heavy for their power, fairly inefficient, noisy, and very polluting, the risk of engine problems due to previous operating or maintenance abuse (or both) is simply too high for us given what we have since learned about this engine here and in the UK.

So our assessment of the FL120 is it's potentially a very reliable engine but is very susceptible to having its life shortened by previous operators. It is also very much out of date in terms of weight, power to weight, noise, emissions, and maintenance intervals. It has some weak features, particularly the head gasket which has a tendency to blow if you look at it too hard. Well, that's an exaggeration, but if the engine overheats the gasket will blow and the head will warp.

The stock raw water pump is a failure waiting to happen. Not the Jabsco pump, but the Lehman-designed drive coupler. The coupler cannot be replaced because they are no longer available , and they can't be repaired because the repair doesn't last very long. Fortunately, there is a solution and that's to replace the old pump and drive coupler with a brand new one-piece pump that fits perfectly and does an even better job of pumping. We had this done to our engines: according to the Smiths at American Diesel who know more about Lehmans than God, this is one of the four best improvements that can be made to an FL120.

FL120 parts are fairly well available now, but that is going to be ending in the not-all-that-distant future. Parts availability will be more and more difficult and the prices will climb pretty dramatically.

Bottom line: In our opinions, don't buy a boat with FL120s. There are far, far better engines out there with much brighter futures and they can be found in a bazillion good boats.

Baker 01-05-2015 12:56 PM


Originally Posted by djmarchand (Post 295894)

* Budgetary considerations will probably limit consideration of newer Cummins Q engines or Cat C's. I doubt if you will find many boats with a pair of those for less than $500K.

I have seen numerous boats well under $500k with these in them. And without looking. Some of the newer Luhrs Sportfishes have them as well as the Newer larger Mainships...who knows why. Scale it back a bit and let's not forget about the QSB's and the QSC's. ALL excellent choices.

As far as factory support goes, you just will NOT beat Cummins or Caterpillar.

Forkliftt 01-05-2015 05:38 PM

It looks like you have certainly been doing your homework 😊. That's as as close to an overall assessment of available engine choices as I have possibly ever seen.
You brought up the Lehman engines as well. We run the FL135's so I know a little about these.
I've been on this forum since Baker started it and am also a member of Boatdiesel- and I don't think you will find much negative mentioned about the 120 or the 135 Lehman. Marin throws his opinion out there occasionally- and I suspect it's just to rile the rest of the Lehman owners out there and to keep us from boasting so much😊. The 135 came out around June '82, so from there up you will pretty much see the 135. IMO they are both great, simple, reliable engines that will probably last longer than most of the boats they are in given basic maintenance and clean fuel. The 120 has a suggested maintenance item (injector pump oil change) at 50 hours that I'm sure could be a bit of a pain, but beyond that the maintenance needs are similar to most other four stroke/ non EPA compliant engines. Im sure parts availability will be great for years to come from American Diesel. And if AD ever fell out of love with the Lehmans, there would be several other sources (but certainly not as knowledgable) ready to step up due to how many are out there.
And of course, the Perkins, Cats, Volvos, etc all bring much to the table as well. I just wouldn't want you to pass on a Lehman powered prospect from fear it might not be able to get you home after you purchased it 😎👍

1983 Present 42 Sundeck
Twin Lehman 135's

ktdtx 01-08-2015 12:30 AM

Thanks for all the feedback.
Will take this information with me when I head up to Seattle for the Boat Show in a few weeks.


Old deckhand 01-08-2015 10:10 AM

The 4 cyc DD 8.2 is a problem engine. DD attempted several solutions to fix the head problem with limited success. I had one that had all of the upgrades and it still had problems. Ultimately did the repower thing.

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