Mercury 115 / 150 FourStroke – Outboard
Photo: Matti Blume, CC BY-SA 4.0, via Wikimedia Commons (cropped)

Mercury · Outboard

Mercury 115 / 150 FourStroke

This page covers two related Mercury four-cylinder outboards: the 150 FourStroke, a 3.0-litre engine launched in October 2011 (serial 1B905505 on), and the 2.1-litre engine of June 2014 that Mercury sells as the 75, 90 and 115 (80 and 100 hp in some export markets), with 115 Pro XS, Command Thrust and SeaPro versions; the 150 also comes as 150 Pro XS and 150 SeaPro, and a 135 hp 3.0-litre exists for some markets. Both have a chain-driven overhead camshaft, eight valves, fuel injection, an oil drain valve and a drip trough under the oil filter, and they share many service parts: NGK ZFR5F plugs, thermostat, impeller and pump kits, the in-line fuel filter and the gearcase side anodes. They differ in oil filter, gearcase, oil quantity and charging: the 150 has a belt-driven 60 A alternator, the 2.1-litre a 35 A charging system under the flywheel. The older 75–115 EFI with 1.7 litres (up to serial 2B094995) and the supercharged four-cylinder 150 Verado are different engines with different parts, so read the serial number on the transom bracket before ordering. Boat builders' lists in Europe use names such as F150 XL EFI or F115 EXLPT EFI; both engines are still in Mercury's 2026 range.

Manuals & documents

The links go straight to Mercury. We host no manuals or drawings — the manufacturer’s copy is the current one.

Wear parts & part numbers

PartOEM numberAlso fitsNote
Engine oil filter877761K012,3,4Sierra 18-77581150 (serial 1B905505 on). The same filter as the older 1.7-litre 75–115, not the 2.1 litre. Oil the gasket and tighten 3/4 to 1 turn after it touches; empty the drip trough under it through its own drain plug.
Engine oil filter8M0162829 · 8M01628306,7,8,9Sierra 18-791452.1 litre (serial 2B094996 on): 8M0162829 is the Mercury-branded filter in the service kits, 8M0162830 the Quicksilver one in the parts diagram (formerly 8M0065103). Tighten 3/4 to 1 turn after the gasket touches.
Fuel filter (engine)879885Q11,12,13,4Sierra 18-771810Both engines: the low-pressure in-line filter under the cowl that the owner may change (on the 150 it sits in a bracket with a lift handle). Fit it with the arrow towards the engine; the high-pressure filter is a dealer job.
Fuel filter (engine)8M009080912,6,14—2.1 litre: filter screen in the fuel supply module, part of the 300 h kit; a dealer job.
Spark plug8M020472816,6,17replaces 8M0057936NGK ZFR5F4,15Mercury's number for the NGK ZFR5F, four per engine on both: gap 0.8 mm, 27 N·m, anti-seize on the thread in salt water.
Thermostat8M009081919,20,21replaces 892864T06Sierra 18-363318Both engines (150 from 1B905505, 2.1 litre); replaces 892864T06 and is part of the 2.1-litre 300 h kit. The Sierra part is listed for the 2.1 litre only.
Raw water pump impeller43026T223,24,25Sierra 18-305622The same water pump impeller on both engines; Mercury has it replaced every 300 h or 3 years.
Impeller kit (with gasket)8M01005276,26—Impeller kit with gaskets, plates, seals and key, without the pump housing; the one in the 2.1-litre 300 h kit, and dealers list it for the 150 too.
Water pump repair kit8M009452924,27—Complete pump kit with upper and lower housing, plate, gaskets, seals, key and impeller; for the 2.1 litre from 2B094996 and the 150 from 1B905505.
Water pump repair kit8M006104023,24,28—Upper water pump repair kit with impeller, housing and gaskets; shown in the parts diagrams of both engines.
Anode (lower unit)826134Q · 826134T23,24,6,29,30,4—Side-pocket aluminium anodes, two per gearcase (one each side above the anti-ventilation plate) on both engines. The parts diagrams show 826134Q, the 2.1-litre 300 h kit 826134T. Never paint an anode.
Anode (lower unit)76214Q523,31,4—150: the fourth anode, a flat plate under the rear of the anti-ventilation plate. One source names the kit in the 150 diagram; the dealer page lists it for Mercury outboards in general.
Anode (clamp bracket)8M005777232,33—150 (also 150 Pro XS, 150 SeaPro and the 135): aluminium anode on the bottom of the power trim unit between the transom brackets.
Anode (clamp bracket)818298Q1 · 818298T134,6,35,36—2.1 litre: anode kit on the bottom of the transom bracket assembly (power trim pump); the diagram shows 818298Q1, the 300 h kit 818298T1.
Gear oil plug gaskets8M020469338,6,37replaces 830749Sierra 18-2430-937Sealing washers for the gearcase fill/drain and vent plugs on both engines; replace them if damaged, they come in every service kit.
Serpentine belt8M023501339,40,4replaces 8M0031641—150 only (serial 1B905505 on): 4-rib alternator belt, replaced by the dealer every 300 h or 3 years.
Alternator8M006523939,41—135 and 150: 60 A belt-driven alternator; the 150 parts diagram shows it replacing the first one, 8M0057693.
Service kit8M009423242,43—150 (serial 1B905505 on), 100 h kit: oil filter, low-pressure fuel filter and gearcase drain seals; oil and gear lube not included.
Service kit8M009423344,42,45—150 (serial 1B905505 on), 300 h kit: oil filter, low- and high-pressure fuel filters, gearcase drain seal, 4 spark plugs, thermostat kit, impeller kit, alternator belt, two gearcase anodes and the power trim anode.
Service kit8M00978546,46—2.1 litre (serial 2B094996 on), 100 h kit: oil filter, in-line fuel filter and gearcase drain seal.
Service kit8M00978556,47—2.1 litre, 300 h kit: oil filter, 4 spark plugs, thermostat, impeller kit, anodes, in-line fuel filter, fuel filter screen and seals (parts diagram contents).
Oil change kit8M0188357 · 8M01075134,48,49—150: oil change kit with oil, filter and drain hose; 8M0188357 is the Mercury kit, 8M0107513 the Quicksilver one (oil change kit table in the 2025 manuals).
Oil change kit8M0107510 · 8M010751115,50,51—2.1 litre (serial 2B094996 on): 8M0107510 is the Mercury kit (oil, filter, drain hose), 8M0107511 the Quicksilver one. The 1.7-litre kits 8M0081917/8M0081913 do not fit.
Propeller shaft grease8M01904724,15,52—Mercury Extreme Grease, named in the 2025 manuals for the propeller shaft (every 100 h and whenever the propeller comes off) and the steering cable fitting.
Power tilt fluid92-858074K014,15,53—Mercury/Quicksilver Power Trim and Steering Fluid for the trim reservoir (level checked every 300 h or 3 years); automatic transmission fluid if it is not available.

Numbers checked against the sources below on 23 October 2026. Always confirm against your serial number and exact type before ordering.

Service intervals

TaskInterval
Oil level checkBefore every outing: oil level, lanyard stop switch, fuel system for leaks, transom bolts, steering and propeller4,15
Fresh-water washAfter every use in salt, polluted or muddy water: engine off, hose on the flush connector in the bottom cowl, tap half open for about 15 minutes; rinse salt off the powerhead and gearcase4,15
Engine oil changeEvery 100 h or yearly, with a new oil filter; more often with a lot of trolling4,15
Oil filterEvery 100 h or yearly4,15
Gear oil changeEvery 100 h or yearly; look for water (milky lube) and metal chips when draining4,15
Fuel filterLow-pressure filter: check every 100 h or yearly, replace if dirty; high-pressure filter only by a dealer (the first 2.1-litre manual of 2014 had it replaced every 300 h)4,15,54
AnodeCheck every 100 h or yearly, more often in salt water; replace before it is used up4,15
Spark plugReplace every 300 h or 3 years; in salt water also remove and inspect every 100 h or yearly4,15
ThermostatInspect every 100 h or yearly for corrosion or a broken spring, and check that it closes fully when cold (dealer)4,15
BatteryEvery 100 h or yearly4,15
LubricationPropeller shaft every 100 h or yearly (propeller off); shift shaft drag link every 100 h (dealer); all lubrication points and the upper driveshaft splines (dealer) every 300 h or 3 years, more often in salt water4,15
Raw water impellerReplace every 300 h or 3 years (dealer), sooner after overheating or when the water pressure drops4,15
V-belt replace150 only: replace the alternator belt every 300 h or 3 years (dealer)4
Full serviceEvery 100 h or yearly: cowl seals and air intake parts, plus transom bolts to torque and other fasteners (dealer); every 300 h or 3 years: power trim fluid level, and wiring and connectors (dealer)4,15

Hours or years, whichever comes first, from Mercury's 2025/2026 operation manuals 8M0231628 (150) and 8M0231611 (75–115); “dealer” marks the jobs Mercury leaves to a dealer. Running-in: for the first two hours vary the throttle up to 4500 rpm (three-quarter throttle) without long idling, then for eight hours no more than five minutes at a time at full throttle. Older editions differ in details: the first 2.1-litre manual of 2014 replaced the spark plugs only after the first 300 h and then inspected them, and the 150 manual of 2011 did not list the plugs at 300 h. Valve clearance is not in the owner's schedule; ask the dealer.

Specifications

TypeInline four-cylinder four-stroke, single overhead camshaft driven by a timing chain, 8 valves, electronic fuel injection, raw-water cooled55,56,57,58
Displacement75–115: 2061 cc (2.1 l); 150: 3.0 l (183 cu in)15,4
Bore × stroke75–115: 90 × 81 mm; 150: 101.6 × 92 mm54,59
Power55 kW (75 hp), 59 kW (80 hp), 66 kW (90 hp), 74 kW (100 hp), 85 kW (115 hp, also 115 Pro XS); 150: 110 kW (150 hp)15,4
Full-throttle range75/80: 4500–5500 rpm; 90/100/115: 5000–6000 rpm; 115 Pro XS: 5300–6300 rpm; 75–115 SeaPro: 5000–5500 rpm; 150: 5000–5800 rpm; 150 Pro XS: 5200–6000 rpm; 150 SeaPro: 4800–5300 rpm15,4
Idle speedIn neutral, warm: 700 rpm (75–115) or 650 rpm (150); up to 800 rpm when cold or when the idle rises automatically to charge a low battery15,4
Alternator75–115: 35 A (441 W); 150: 60 A (756 W), belt-driven, with idle charge60,4
BatteryLead-acid 1000 MCA or 800 CCA, or 180 Ah (150) / 65 Ah (75–115); the 2025 manuals also allow a lithium iron phosphate cranking battery of at least 800 A15,4
FuelUnleaded petrol, at least 91 RON for most models (USA/Canada: 87 AKI); up to 10 % alcohol (E10); the 2014 bulletin for the 2.1 litre still said 90 RON15,4,61
Engine oil capacityWith filter change: 5.2 l (75–115) or 6.0 l (150), to the middle of the dipstick range15,4
Engine oil gradeNMMA FC-W SAE 10W-30 for all temperatures; FC-W 25W-40 mineral or synthetic blend as an option; SeaPro: 25W-40 recommended, 10W-30 at 0 °C or below15,4
Gear ratio75–115: 2.07:1 standard gearcase, 2.38:1 Command Thrust (larger gearcase, SeaPro only with this one); 150: 1.92:1; 150 Pro XS: 2.08:115,4
Gear oil capacity75–115: 800 ml standard, Command Thrust 810 ml right-hand or 790 ml left-hand (first 2014 manual: 760 ml); 150: 830 ml, 150 Pro XS 970 ml (2011–2014 manuals: 780 ml right-hand, 545 ml left-hand)15,4,54,59
Gear oil gradeMercury or Quicksilver High Performance Gear Lubricant15,4
Spark plugNGK ZFR5F (4), gap 0.8 mm, 16 mm hex, 27 N·m or finger-tight plus 1/4 turn15,4
Valve clearance (cold)75–115: intake 0.050–0.102 mm, exhaust 0.128–0.179 mm; 150: intake 0.075 mm, exhaust 0.25 mm (printed up to the 2018 manual; a dealer job)62,63
Tightening torquesOil drain valve 15 N·m (never open it more than 2.5 turns); spark plugs 27 N·m; propeller nut 75 N·m; transom mounting bolts 75 N·m (122 N·m with metal lift plates or setback brackets)15,4
Shaft lengthL and XL (XL 12.7 cm / 5 in longer); 2.1 litre: transom height 50.8 cm (20 in) or 63.5 cm (25 in), about 19 mm lower than Mercury's older 75–125 outboards; 150 also as CXL with counter-rotation for twin installations4,61,23
Dry weight150: 206 kg (455 lb) at launch, the lightest 150 hp four-stroke of its day according to Mercury; 2.1 litre: from 163 kg (359 lb) with the 20 in shaft56,64
Sound levelAt the driver's ear (ICOMIA 39-94): 79.2 dBA (75–115), 82.9 dBA (150)15,4
Engine protectionEngine Guardian: on a sensor fault (for example overheating or low oil pressure) the horn sounds and power is reduced; return the throttle to idle to reset it15,4
Models2.1 litre: 75, 80, 90, 100 and 115 (80 and 100 for some export markets), 115 Pro XS, Command Thrust 90 and 115, SeaPro 75/90/115; 3.0 litre: 150, 150 Pro XS (in the manuals from 2018), 150 SeaPro, and a 135 hp version for some markets15,4,63,60,65
Years built150: since October 2011 (serial 1B905505 on); 2.1 litre: since June 2014 (serial 2B094996 or 2B095049 on, depending on the parts list); both still built in 202656,55,66,46,4
Predecessor2.1 litre: the 75/90/115 EFI FourStroke with 1.7 litres (1731 cc), up to serial 2B094995; 150: the supercharged four-cylinder 150 Verado, which the 150 FourStroke undercut by about 25 kg (55 lb)67,3,56

Good to know

  • Read the serial number on the transom bracket before buying parts. A 75–115 up to 2B094995 is the older 1.7-litre engine with a different oil filter and different oil change and service kits; the 2.1 litre starts at 2B094996 (2B095049 in the parts catalogue). The 150 FourStroke starts at 1B905505; the four-cylinder 150 Verado of the same years is a different, supercharged engine.3,8,66
  • The oil change needs no pump: tilt the motor up for about a minute, then back to vertical, fit a 12 mm hose to the drain valve and open it no more than 2.5 turns (16 mm spanner, 15 N·m when closing). The oil filter sits above a drip trough with its own plug and hose connection. Check the level only after the engine has cooled for an hour; within five minutes of stopping it can read up to 1 litre low.4,15
  • On the 150, check the charging if the battery runs low: the belt-driven 60 A alternator needs a new belt every 300 h or 3 years, and on early engines (1B906474 to 1B943665) Mercury found that the alternator end cover could touch the cylinder block, breaking stator wires and cutting the output to 46 A or nothing. Mercury had those engines inspected and corrected by dealers.68,4
  • If the engine has been used in salt water, ask a Mercury dealer about the shift arm stud campaign: the studs on the upper shift arm can corrode and the gear shift can fail. It covers the 2.1 litre from 2B095049 to 3B633935 and the 3.0 litre 135/150 from 1B905505 to 3B625824; engines used only in fresh water need no work.69,65
  • When repowering with a 2.1 litre, mount it one hole lower than an older Mercury 75–125: its transom height is about 19 mm less. The standard gearcase takes the 4.25 in propeller series, the Command Thrust gearcase the larger 4.75 in series, so propellers do not swap between them.61
  • There are three anodes on the 2.1 litre (one each side of the gearcase and one under the transom bracket) and four on the 150 (plus a plate under the rear of the anti-ventilation plate). After starting, always look for the steady stream from the water pump indicator hole; if it is missing, stop the engine at once and check the water intakes, and if they are clear have the pump and cooling system checked before running it again.4,15

Videos & how-tos

Links to YouTube, nothing embedded. The maker’s own channel comes first; the rest are channels we found clear and correct for this model.

Fitted in

Boats whose builder lists it as standard or optional equipment:

  • Quicksilver Activ 805 Cruiser — Mercury F100 EXLPT EFI · F115 EXLPT EFI · F150 XL EFI · Verado 150–200 XL × 2 (2015–2016, twin engines (MY2016 product sheet): 2 × F100 EXLPT EFI or EFI CT, 2 × F115 EXLPT EFI or EFI CT (CT = Command Thrust, the larger gearcase), 2 × F150 XL EFI, or 2 × F150, F175 or F200 XL Verado)

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Sources

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