150 FourStroke
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Mercury SmartCraft Review

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Mercury 150 FourStroke Mercury 150 FourStroke
The Mercury 150-hp FourStroke outboard has the low-end torque of a two-stroke and the fuel-efficiency that made four-strokes popular. It is the lightest outboard in class at just 455 lbs. (206.8 kgs.) With this model, Mercury Marine moved heaven and earth to make her durable in saltwater…or anywhere else.

Key Features

  • Large displacement for "out of the hole" performance
  • Compact design
  • Fewer parts
  • Quiet operation
  • Tested in all conditions for all-around performance
  • Stainless steel components for corrosion protection and durability
  • 60 amp alternator has greater charging for longer battery life
  • 3-year corrosion warranty

Mercury 150 FourStroke (Outboard) Specifications
Horsepower 150-hp
Type of Engine 4-Stroke
Number of Cylinders 4 Cylinders
Configuration In-line
Weight (lbs/kg) 455.00 lbs / 206.38 kg
Fuel Delivery Fuel Injected
Displacement (cu/cc) 183.00 cu / 2,998.83 cc
Shaft Length Options 20'' (508 mm) / 25'' (635 mm)
Shift/Throttle Control Cable
Recommended Fuel Unleaded Regular 87 Octane Minimum
Alternator Output 60 amp / 75 watt
Engine Monitoring System Standard

Mercury 150 FourStroke Captain's Report

The Mission of the Mercury 150 HP FourStroke

Simply stated the mission of the new Mercury 150 HP FourStroke is to be absolutely the best, most dependable outboard engine on the market for both saltwater and freshwater applications.

High Torque. Before this engine was designed, Mercury conducted extensive surveys among a broad spectrum of boat owners in both fresh and saltwater across North America and around the world. It found out that watersports-oriented boaters, bass anglers, and most everyone else wanted a boat with high torque in the low rpm range for fast hole shots and to get a heavy boat up fast without wallowing along…or having to move weight to the bow to get on plane.

Saltwater Safe. It also found out that saltwater boaters wanted an engine which would start every time, not load up and choke after prolonged trolling, and would be impervious to saltwater corrosion. And, of course, everyone wanted fuel efficiency.

The Last Shall Be First. One of the advantages of being the last company to market with a new product is that Mercury’s engineers could look at all of the competition, then figure out how to improve on every 150 engine in the market. The new Mercury 150 would have to have the low-end torque of a 2-stroke, be lighter than the other 4-strokes, be bulletproof when it came to saltwater corrosion, and earn a reputation over time for durable maintenance-free operation.

We are only a little more than a year into this engine's life, but word is drifting back from the field that the engine is fulfilling its durability and performance expectations.

Mercury 150 HP FourStroke
The Mercury 150 is a multi-port EFI engine engineered to start every time in both hot and cold conditions. It has a trim range of 20-degrees and her cowling weighs just 16 lbs. (7.27 kgs.) thanks to composite construction.

Distinguishing Features

Greatest Displacement. Some engineers like to say that “there’s no replacement for displacement” and so it is not surprising that the Mercury 150 has the largest displacement of any outboard engine in class – 183 cubic inches or 3000 cc/3.0 L. That is 12.8% more than its chief rival.

Lightest 4-Stroke. The lightest Mercury model weighs 455 lbs. (206.8 kgs.), dry. That’s 19 lbs. (8.6 kgs.) lighter than the previous lightweight in the 4-stroke class.

Significantly Fewer Parts. This is a biggie because it affects so many things – weight, durability, fuel efficiency and cost. While it still has a lot more parts than a 2-stroke, the Mercury 150 has a remarkable 18% fewer parts than her chief rival. At one stroke that translates in to better fuel efficiency and greater durability.

Low-Friction SOHC Valve Train. By having just two large valves per cylinder instead of four, the new Mercury 150 has not only half as many valves, but also half as many springs and cams – all of which can rob power. SOHC engines are famous for producing better torque at the low end and this combined with the greater displacement means the 150 should be as fast out of the hole as a 2-stroke.

No Shims. Because the 150 has no shims she does not need a trip to the service shop to have its lash adjustment after a certain number of hours like most other 4-strokes on the planet. This saves maintenance costs that can run over $500.

Mercury 150 HP FourStroke
The in-line 4-cylinder Mercury 150 is a SOHC design which has a single rocker arm with a "Roller Finger Follower" that was pioneered in Formula One racing engines.

Major Features

Lowest Copper in Aluminum Alloy. Mercury claims that its XK360 aluminum alloy is the most corrosion-resistant among all 4-stroke outboard brands because its copper content is only 0.2%, a fraction of what the other engine makers use. This alloy is used in the block, driveshaft housing, gear case and in the alternator housing. The cast aluminum head has less than 0.15% copper content.

Key Stainless Steel Components. The prop, shift mechanism, drive shafts, trim/tilt rams, tilt tubes, lower yokes and water pump housings among other things are made of 300 Series stainless steel used to avoid corrosion as much as possible, provide strength and long life.

Scroll Intake Manifold. The 150 has a long intake runner manifold designed to insure maximum intake air flow to the engine's 3.0 L displacement cylinders, while helping maintain it's lean, slim profile.

Compact Design. The Mercury 150's profile is smaller than virtually any other engine in class. That means that its outboard well intrusion is less.

60 AMP Alternator. Mercury's alternator is a belt-driven, "on-demand" unit that produces less heat because it is only producing power when it is needed. It has the highest AMP output of any 4-stroke engine on the market, thus supplying adequate power for accessories and keeping the battery fully charged at the same time.

Mercury 150 HP FourStroke
This is the engine oil cooler whose job is to maintain a more consistent oil temperature to prevent oil dilution concerns which are prominent in larger 4-stroke outboards.

Exclusive Oil Cooler and Sump. This design maintains proper oil temperature which enhances performance and extends the life of the engine.

Mercury 150 HP FourStroke
The 150's engine mounts are twice as large as those found in other engines in class. The rubber inside is relatively soft at idle, but compresses at high rpms. By having the upper mounts at a 45-degree angle they can absorb the vibration of opposing forces and not transfer them to the boat.

45-Degree Engine Head Mount System. By placing the engine head mounts at a 45-degree angle Mercury significantly reduces vibration at all points in the power band. Because the mounts are placed further from the power head, high-temperature transfer is significantly reduced which increases the life of the rubber material which dampens vibration in the mount housing.

4.88-Inch Torpedo Gear Case. This beefy gear case becomes particularly important at high speed in a chop when the boat may catch air or when running over an obstruction.

Mercury 150 HP FourStroke
Look closely to see the nipple of the oil release device (A). A half turn (B) of the nut is all that is needed to drain the oil into a clear plastic tube and a container -- no mess!

Mercury 150 HP FourStroke
The oil filter (A) can be unscrewed without a tool, but since it is horizontal it will drip some oil. Mercury has installed a drip pan (B) to catch the oil. By putting the same plastic tube (C) as used above on the drain hole this oil, too, can be removed without mess. The base of the dipstick (D) can be seen. All maintenance items are color-coded.

No Mess Oil-Change System. The Merc 150 has a special valve that fits a plastic tube to easily drain the engine oil into a container without making a mess. The oil filter can be easily removed without special tools and just below it is a "spill tray" to receive the oil that unavoidably will seep out of the horizontal filter. The tray can also be fitted with the same plastic tube to run the filter spillage into a container.

Heavy-Duty Transom Brackets. One place where Mercury engineers decided not to save weight was on the transom bracket, in fact it is 22% heavier than that found on its prime competitor.

Mercury 150 HP FourStroke
Mercury is staking its reputation on its new anti-corrosion technology to increase its penetration of the saltwater market.

Saltwater Friendly

The new Mercury 150 was specifically designed to be a sterling product for saltwater applications. First, that means to be as corrosion-resistant as modern technology and metallurgy permit. Mercury has done that with its patented low-copper aluminum alloys that are generally agreed to be a significant advancement.

Secondly, its "MercFusion" paint system features an electro-deposition paint process which electronically bonds paint to metal throughout the engine, even inside internal water passages. Further, of the stainless steel components mentioned above go a long way to solving historical corrosion problems.

Finally, Mercury has installed a waterproof electrical system and connectors that sit inside a tightly sealed cowling that has baffles to let air in and force water out.

The sum of all of these features is the creation of an outboard engine that should be second to none in saltwater.

Recommended Applications

A Workhorse. The Mercury 150 probably has the widest applications of any outboard engine in the company's line-up -- for both saltwater and freshwater use. In either single or twin installations it is appropriate for --

  • Pontoon boats
  • Multi-specie fishing boats
  • Bass boats
  • Sportboats
  • Center consoles
  • Dual consoles
  • Bay boats/flats boats
  • Deckboats
  • Ski & fish boats
  • Inflatable boats
  • Yacht tenders

Mercury 150 HP FourStroke
There are literally millions of boats around the country that need to be repowered because they are wearing out, hard to start, and guzzle gas to say nothing of their carbon emissions. The new Mercury 150 was built to service that need.


Boats Designed for 2-Stroke Engines. When the first generation of 4-stroke engines were first placed on boats designed for 2-stroke motors, many boats did not perform well until solidly on plane. In many cases 4-stroke engines struggled to get the bow down and the stern up. The reason this happened was because the boats were designed for the relatively low weight and the high torque generated by 2-stroke engines.

2-Stroke or Four? In the meantime most builders have slowly retooled their outboard boats to better handle the 4-stroke engines' higher weight and torque characteristics. This redesign usually made the boats easier to get on plane with 4-stroke engines, but they still couldn't compete with 2-stroke engines in some important applications. Today, boaters are repowering both older boats intended for 2-stroke motors and the newer versions designed for 4-stroke power. But which engine technology to use?

All-Purpose Engine. The Mercury 150 FourStroke has been specifically designed to perform well on all outboard boats of any vintage because of its low weight and high low-end torque. Because it is 4-stroke it has the same fuel-efficiency boaters have come to expect of the new breed of outboards. As a result it is ideal for repower applications.

Mechanical or Hydraulic Steering? The 150 is flexible enough to be able to accommodate mechanical or hydraulic steering, the Mercury "Big Tiller" system, mechanical control cables, as well as a full compliment of either analog or digital SmartCraft gauges.

Mercury 150 HP FourStroke
Every year or 100 hours the engine low-pressure fuel filter needs to be checked and possibly replaced. It is as easy as pulling up on the yellow handle and detaching it. No tools are needed -- and no service tech.

Easy Maintenance/Low Maintenance/Low Cost

As remarkable as it may sound, Mercury is actually the first outboard engine maker to install a plate on an engine explaining when and how to maintain it. The plate is easy to read and in plane English and we predict it will be the start of a trend. Here is what is says--

"Every 100 Hours of Use or Once a Year."

  1. Inspect anodes
  2. Inspect low-pressure fuel filter
  3. Inspect spark plugs. In saltwater apply ant-seize compound to threads
  4. Inspect thermostat
  5. Replace engine oil and filter
  6. Replace gear case lubricant

"Every 300 Hours of Use or Every 3 Years."

  1. Replace the accessory drive belt
  2. Replace the spark plugs
  3. Replace the water pump impeller

That's It. What could be more simple or more obvious? The engine does not have to go back to the dealer for maintenance at either 100 hours or 300 hours. There are no shims to be re-adjusted by the dealer. Rather, the engine has directions printed right on its side and color-coded engine maintenance locations. But there is more…

Maintenance Videos On A Smartphone. A QR code icon that can be read with a smartphone is printed right on the engine maintenance plate. When the proper app is downloaded the QR code will call up maintenance instructions with more details. There are even videos on this Mercury website which will -- step-by-step -- take an owner through the simple procedures. This is the next best thing to having a service tech on hand -- and a lot cheaper.

Mercury 150 HP FourStroke
The Age of Aquarius is long past and now we're into the Age of the Internet which is quickly becoming the repository of all useful information…including a video on how to change the oil of the Mercury 150.

Built to Last

The genius -- in our opinion -- of the Mercury 150's engineering and overall design is how its features create more than one, two, or even more attributes. For example, the class-leading 3.0 L displacement not only gives the engine 0-to-plane times on a par with a 2-stroke engines, but it also means at normal cruising speeds the engine does not have to work so hard to produce the required power. That means fewer rpms are needed. The engine is not stressed to its limits. It should last longer.

Robust Displacement Indeed, look at 250-hp engines from nearly any engine maker, including Mercury, and it becomes readily apparent that most hover around the 3.0 liter range in displacement. Yet with Mercury's new engine that displacement is only required to produce 150-hp.

Consequences of Good Design. The engine has 18% fewer moving parts to save weight, but that attribute also provides the added benefit of fewer parts to wear out or break. The stainless steel used to protect against saltwater corrosion pays off a second time because it is so strong and durable. The weight and cost of the parts eliminated has gone into better materials for the parts that are used, which isnsome cases are heavier than normal in class for durability's sake.

Mercury 150 HP FourStroke
Lightweight aluminum bass boats powered by the Mercury 150 get their bow down fast and on plane quickly because of the SOHC design with 3.0 L displacement.

Freshwater Applications All of the features that make the 150 so durable in saltwater should make it virtually bulletproof in freshwater. It is a mistake to think that corrosion can't happen in freshwater because, of course it can.

Juice in the Water. That is one reason why the 150 has sacrificial anodes. Marinas often have stray current in the water that can quickly eat through vulnerable metals. In some places there are chemicals and salts in the water that can do damage and that's why the engine should be regularly flushed even in freshwater locations. The Mercury 150 has a handy fitting for a garden hose for just that purpose.

Fast Hole-Shot Times. Boaters in freshwater tend to be more concerned about fast and powerful acceleration. Bass anglers want it so they can be first to the honey hole during tournaments. Watersports enthusiasts want high initial torque to get skiers and wakeboarders up fast, even with a boat load of people. The 150's SOHC design, and 3.0 L displacement, combined with its EFI system makes performance on this score competitive with 4-stroke engines.


50% of all outboard boats sold last year in the U.S. fell in the 14' to 19' (4.25 to 5.79 m) range. So, for a "generic" test boat we chose an aluminum fishing boat that is in the heart of that range.

Test Boat. Our test boat had a LOA of 17’6” (5.33 m), and a beam of 7’9” (2.4 m). With an empty hull weight of 1,345 lbs (610 kg), full fuel, two people and the 150 Mercury outboard, we had a test weight of 2,382 lbs (1080 kg).

On Test Day. The 150-hp 4-stroke Mercury outboard motor we tested swung a 13 3/4 x 20 three-bladed stainless steel Enertia prop. Test day was almost perfect: 78F, 72% humidity and light breeze.

Consumer Caveat. Consumers using this data to gauge the performance of boats they are considering should focus on the total weight of the boat as tested, its beam, and the prop geometry. These are the most important variables.

WOT Speed. Our aluminum test boat reached a top speed at 5650 rpm of 53.3 mph. At that speed we were measuring a fuel burn of 14 gph for 3.81 statute miles per gallon.

Best cruise came in at 3000 rpm and 25.2 mph. That reduced the fuel burn to 3.2 gph or 7.88 statute miles per gallon. Not only is that the most efficient planing speed for our test boat, put it was the most efficient speed any during out test. That is to say, even at a very slow trolling speed of 4.3 mph (1000 RPM) we got fewer miles per gallon -- 5.06 mpg.

Mercury 150 HP FourStroke

Acceleration. Most impressive was the 150 FourStroke’s acceleration which plays well into the watersports crossover. We reached planing speed in only 2.9 seconds, accelerated to 20 mph in 5.3 seconds, passed 30 mph within 7.2 seconds, and continued accelerating through 40 mph in 9.3 seconds. These are impressive times, the kind that we often get on PWCs. The 150 also provided impressive mid-range acceleration. From our 30 mph cruise, throwing the throttle forward had us quickly outpacing the camera boat.


Adding power to the 150 4-stroke only caused the bow of our test boat to come up 8.5-degrees upon acceleration. And we settled into a 3-degree bow-high cruise attitude which is appropriate for this size and type of boat.

The test boat was rigged with Sea Star hydraulic steering system that was offered as an option and it really made a difference with effortless handling. We noticed no torque effect during acceleration and certainly not during any of the straight runs at wide open throttle. Even with this light boat, the engine's 450 lb. (204 kg) gross weight was barely noticeable. Maneuverability comes from its 120-degree turn radius.

At the end of the day when its time to haul the boat, the single stage trim assembly will trim the 150 completely out of the water in 13.5 seconds.

Mercury 150 HP FourStroke
Best cruise was recorded at 25.2 mph where we got a noteworthy 7.88 miles per gallon.

Performance Factors. When we look over the Mercury published data on their own engines we see that bottom shape, prop selection, and max rpm have a lot to do with performance, in addition to weight and beam. With so many tests we can't report on them all, but what we can do is analyze them, throw out seeming anomalies or those tested in extreme weather conditions and zero-in on some generalities for several classes of boats.

Mercury 150 HP FourStroke
Small center consoles up to about 3,000 lbs. (1,363 kgs.) are an appropriate application for a single Mercury 150.

Center Consoles. Center consoles designed for bay and flats fishing and near coastal work typically need only a single 150-hp engine. The boats in this class that Mercury tested ranged in length from 18' to 22' (5.48 m to 6.70 m) and weighed from 1,700 lbs. to 3,000 lbs. (772 kgs. to 1,363 kgs.). That is quite a range, and one might expect a sharp dichotomy in performance, but here bottom shape and even bottom paint seemed to be equally important factors.

Mercury 150 HP FourStroke
Multi-specie boats are a prime market for the Merc 150 both for new boat installations and for repowering.

Multi-Species Boats. Typically these boats are aluminum and lightweight. The boats we checked were from 17' to 20' and weighed from 1,333 lbs. to 1,900 lbs. We threw out the top and bottom boats and just examined the rest.

WOT. Wide open throttle speeds ranged from 42 mph to 51 mph with most boats in the 48 to 50-mph range, even the heaviest ones.

Best Cruise were all scored at 3000 rpm with speeds ranging from 16.7 mph to 23.0 mph with most clumped from 19.7 to 23 mph. The fastest boat's best cruise was recorded at 3500 rpm and 27.6 mph. All of the boats could travel in the high 20s with just a small penalty in fuel consumption.

0-to-20. Mercury techs do not record 0-to-plane times, preferring instead to measure 0-to-20 and 0-to-30 times. All the times for 0-to-20 fell within 3.8 seconds to 4.7 seconds, with most being from 4.2 to 4.4 seconds. Our best guess is that 0-to-plane times would be from .5 to 1.0 seconds less.

Mercury 150 HP FourStroke
Because the Mercury 150 has a low profile and is compact, it will fit into the outboard well of most boats when tilted up, something that is not a problem on this pontoon boat.

Pontoon Boats. Mercury has clearly targeted the 150 FourStroke for the pontoon boat market. Again we threw out the top and bottom numbers to get a better idea of how the boats performed with a 150 Mercury as a class.

WOT. All but one of the boats we checked were triple-toons. Top speed ranged from 31.8 to 42.8 mph. Yes, the 31.8 speed was turned in by a twin-toon boat, which we think is remarkable.

Best Cruise. Here, all best cruise speeds were all slightly above the mid-teens at 3000 rpm, except one boat. Her best cruise was at 3500 rpm and she went 22.3 mph. At from 4000 to 5000 rpm all of the boats traveled in the 22 to 29 mph range, depending on how much power was applied.

0-to-20. All times were in the low 4 second range except one hopped-up toon that hit 20 mph in 3.1 seconds, according to the Mercury techs.

Mercury 150 HP FourStroke
Sportboats under 20' (6.09 m) seem to perform well when powered by the Mercury 150 according to Mercury testing data.

Sportboats. Outboard engines are having a resurgence in sportboats after being virtually shut out of this category for the last 30 years, victim of the 3.0 L sterndrive engine. Typically the sportboats tested by Mercury had displacements from 1800 to 3000 lbs. (818 to 1,363 kgs.). Beams were generally 8'6".

WOT. Top speed ranged from 35.3 mph to 51.7 mph with most from 43 to 45 mph.

Best cruise ranged from 22 mph to 25 mph, with the lightest boats doing the best.

0-to-20. Here, times were between 3.9 and 4.5 seconds and again we figure that these are about .5 to 1.0 seconds slower than the time-to-plane.


The standard stated limited warranty period for the Mercury 150 engine is three years. Further, there is an explicit additional corrosion warranty for three years as well.

Anyone who has seen the dueling outboard "incentive" ads knows that from time to time the engine companies have extended warranty programs. Mercury Marine does this, too. However, there is a difference between Mercury's special extended warranty programs and those of most other manufacturers.

Additional Years? Mercury backs the warranty itself for the additional years, usually five, and does not buy what is known as a "service contract" from a third party insurance company. The boating industry's experience with extended service insurance contractors has been mixed, at best. We like "factory-backed" warranties because it is less likely to have finger-pointing, bureaucratic claim slippage, and unfulfilled promises.


The Mercury 150 4-stroke has been out in the field for a number of years in both freshwater and saltwater locations. We have gotten only positive feedback and we think this is probably one of Mercury’s best outboard products. In a recent statement the company said that the 150 4-stroke is “…the smallest, lightest, most durable, easiest to maintain, most versatile 150 4-stroke in the industry…” and while we’d expect a statement like that from the proud parent, in fact we have no reason to think it is not true.


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