....it seems to me that I see a lot more problems posted by TF members than any other make and model.
Question: "Owners of FLs, knowing what you know now, would you prefer a different make and model engine to power you boats? "
The FL120 was put in countless recreational boats in the 60s, 70s, and early 80s. Particularly the ones built in Asia. And these happen to be the kind most often purchased by people getting into this kind of boating.
My own theory is that these engines, because they are still so common, tend to be run by many boaters as though they were a much more modern engine. And this, I believe, contributes to a potentially earlier than normal demise.
I have a Land Rover that I bought new in 1973. While it has a gasoline engine the engine is based on an engine Land Rover designed and built as a diesel. Long story why they did this but the bottom line is they did not want to operate two engine assembly lines for the same vehicle. It's a tough little engine developing a whopping 68 hp. Top speed of the LRC is about 60 mph.
When I bought the thing, it's "cruising speed" of 45-50 mph was just fine in the traffic conditions of the day. When I moved to Seattle in 1979' the national speed limit was 55 mph so I had no problems commuting on the freeways.
But today, if I were to try to drive the thing with even a hope of surviving today's traffic, I would destroy that engine in pretty short order as it would be running at the upper end of its rpm band almost the whole time.
I believe--- and have been told by an acquaintance in the UK who built a career on servicing, repairing, and overhauling Ford of England engines of all types ---that the Ford Dorset engine is happiest and will last the longest when operated under a constant load in the rpm range of 1500 to 1800. Sustained operation above 1800 will, in his experience, shorten the service life of the engine. As will operation at constantly varying engine speeds and loads, particularly higher rpm and loads, which is why the Dorset was such a miserable failure in its intended purpose as a truck engine but proved to be an excellent engine for industrial and agricultural applications.
But, our acquaintance said (at the time we met him he had a boat with an FL120 in it) sometimes people who buy an older boat with this engine are frustrated by the slow speed they get at 1500-1800 rpm. They want to go faster like the newer boats they see. And if the have a semi-planing hull they can. So, he said, they run their FL120s at 2000 or 2200 rpm or whatever. And while there are never any guarantees, this practice greatly increases the chances of a failure. The FL120 he said, has little tolerance of high heat. Overheating is the surest way to kill a Dorset diesel or the various marinizations of this engine including Lehman's.
While this is certainly no guarantee of a long, trouble-free life, we operate and service our two FL120s as though it was 1960. To that end we cruise at 1650 and in 14 years the engines have been over 1800 rpm exactly once and that was to get data for the prop shop.
To answer your question, we would never select the FL120 if we had a choice of engines to pick from. We would much prefer a newer generation engine, one more efficient, lighter, less polluting, etc.
...not because of any "maintenance/failure issues....
