If you're hunting for a reliable mid-range engine, the nissan 40 hp outboard motor has probably popped up on your radar more than once. It's one of those engines that carries a bit of a cult following, especially among fishermen and weekend boaters who value simplicity over flashy digital displays. While Nissan eventually stopped branding these motors for the US market around 2014, thousands of them are still screaming across lakes and coastal bays today. If you've just picked one up or you're looking at a used listing, there's quite a bit to appreciate about these Japanese-engineered workhorses.
The Tohatsu Connection
The first thing any owner should know is that a Nissan 40 hp outboard motor is essentially a Tohatsu engine in a different set of clothes. For decades, Tohatsu manufactured these engines and simply slapped a Nissan sticker on the cowling for certain markets. This is actually great news for you. It means that even though the Nissan brand name isn't on the shelves at your local marine shop anymore, parts are incredibly easy to find. If you need a water pump kit, a new carburetor, or a prop, you just look for the equivalent Tohatsu part number. It's a relief to know you aren't stuck with an "orphan" engine that can't be fixed.
Why People Love the 2-Stroke Versions
If you find an older 2-stroke Nissan 40 hp outboard motor, you've found a gem. These were often three-cylinder designs (like the NS40D2 model) that provided a surprisingly smooth power delivery compared to the shaky twin-cylinder engines of the same era. They are light—significantly lighter than modern 4-strokes—which makes them perfect for older aluminum boats or skiffs that weren't designed to carry 250 pounds of engine on the transom.
The "holeshot" on these 2-strokes is impressive. When you crack the throttle, the boat jumps onto a plane almost instantly. They're also mechanically simple. There aren't any sensors or complicated ECUs to fail. As long as you give them clean fuel, good oil, and a fresh set of spark plugs every season, they'll probably outlive the boat they're bolted to.
Transitioning to 4-Stroke and TLDI
Later on, Nissan introduced 4-stroke models and the TLDI (Teflow Low-pressure Direct Injection) versions. The 4-stroke Nissan 40 hp outboard motor is a different beast entirely. It's much quieter at idle—so quiet you might accidentally try to start it while it's already running—and it's incredibly fuel-efficient. You can troll all morning on just a few gallons of gas.
The TLDI models were Nissan's answer to stricter emissions laws. They offered the weight and punch of a 2-stroke with the fuel economy of a 4-stroke. While they are fantastic performers, they do require a bit more specialized knowledge to service. You can't just clean the carbs with a can of spray and a screwdriver like you can on the older models. However, for those who want the best of both worlds, a well-maintained TLDI is a powerhouse.
Common Maintenance and What to Watch For
Every engine has its quirks, and the nissan 40 hp outboard motor is no different. The most common issue I see with these—and most outboards, really—is fuel system neglect. Because many of these are older, they often deal with the headaches caused by ethanol-blended gasoline. Ethanol attracts water and can gum up the tiny jets in the carburetors if the engine sits for more than a month. Using a fuel stabilizer and a high-quality water-separating fuel filter is the best insurance policy you can buy.
Another thing to keep an eye on is the cooling system. The water pump impeller is a small rubber part that spins inside the lower unit to move water through the engine block. If you run the motor in sandy or muddy water, that impeller can wear down. I usually tell people to replace it every two years regardless of how many hours they put on it. It's a $30 part that prevents a $3,000 repair bill from overheating.
Don't forget the sacrificial anodes either. These are the little zinc or aluminum blocks bolted to the lower unit. They are designed to corrode so your engine's metal components don't. If they're more than half gone, swap them out. It's a five-minute job that saves your gearcase from pitting.
Finding the Right Propeller
The performance of your Nissan 40 hp outboard motor depends heavily on the prop you choose. If you're using the boat for heavy loads—like taking the whole family out on a pontoon—you'll want a lower pitch prop to give the engine more torque. If you're running a light fishing skiff and want top-end speed, a higher pitch is the way to go.
Most of these motors come standard with an aluminum prop, which is fine for general use. But if you're looking for a bit more "bite" in the turns or a slight increase in speed, switching to a stainless steel prop can make a noticeable difference. Just remember that stainless doesn't give way if you hit a rock, so you might end up damaging the internal gears instead of just bending a blade.
Reliability in the Real World
What really sets the Nissan 40 hp apart is how it handles abuse. These engines were built for commercial fishermen in parts of the world where "preventative maintenance" isn't exactly a priority. They are over-engineered. The castings are thick, the electrical systems are robust, and the pull-start (if yours has one) is reliable enough to save your skin if your battery dies miles from the boat ramp.
I've seen plenty of these motors with 20-plus years of salt-water use that still have perfect compression. The key is a good freshwater flush after every trip. Nissan built their cooling passages fairly wide, which helps prevent salt buildup, but you still want to be diligent about it.
Is It Worth Buying Today?
If you find a used nissan 40 hp outboard motor for sale, should you pull the trigger? In my opinion, absolutely—provided the price is right and the compression is solid. Because the Nissan name isn't as "famous" as Mercury or Yamaha in some circles, you can often find these for a few hundred dollars less than the big-name competitors, even though the quality is arguably just as high (if not higher in some cases).
The main thing to check is the tilt and trim system. If it has power tilt/trim, make sure it moves smoothly and doesn't show signs of leaking hydraulic fluid. Replacing a tilt motor can be pricey and a bit of a pain to do yourself. Also, check the lower unit oil. If it looks like chocolate milk, there's a leaky seal allowing water into the gears. That's not a dealbreaker, but it's a bargaining chip.
Wrapping It Up
At the end of the day, the Nissan 40 hp outboard motor represents a golden era of marine engineering. It's a no-nonsense tool that does exactly what it's supposed to do: get you out on the water and back home again without a fuss. Whether you're running a vintage 2-stroke or a more modern 4-stroke, these engines are easy to love because they're easy to live with. Keep the fuel clean, change the lower unit oil once a year, and that Nissan badge on the side will continue to be a symbol of reliability for a long time to come. It's not just a motor; it's a piece of gear you can actually trust when the weather turns and the dock is a long way off.