Mercury Outboard Parts | 2-Stroke Engines (35-300HP)

(3 products)

This page is for Mercury 2‑Stroke outboard engines in the 35–300HP range. It helps you find compatible parts and service information, including maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main Mercury collection. Scroll to the bottom of this page to start browsing parts for this engine. On the collection page, use the “Filter & Sort” controls to narrow results by horsepower, year range, and part category/section.

Browse All Mercury Parts

How to Identify Your 35–300HP Model

Nameplate location: Look for the serial plate on the transom bracket or swivel bracket. It lists the serial number, model designation, and often shaft length.
Model code and suffix: Letters typically indicate shaft length (S/L/XL), starting/trim options, and control type (tiller vs remote). The serial range is the most reliable way to identify year and parts compatibility.
Platform cues: Smaller 35–90HP models are usually inline-2/inline-3 carbureted 2‑strokes. Midrange 75–125HP can be inline-3/inline-4 carb/EFI. High‑output 135–300HP units are V6 2‑strokes that may be carb, EFI, or Optimax DFI.
Cowl decals: “EFI” and “Optimax” labeling helps distinguish fuel systems; Optimax models also have an onboard air compressor and oil injection components.

Platform Overview

Small Displacement (Approx. 35–60HP)

Feature	Description
Configuration	Inline‑2 or inline‑3 carbureted 2‑Stroke
Common Models	35–60HP 2‑Stroke families (manual or electric start; short/long shafts)
Advantages	Light weight, simple to service, responsive mid‑range
Notes	Many wear parts are shared across adjacent horsepower within a family; confirm by serial number and shaft length.

Midrange (Approx. 75–125HP)

Feature	Description
Configuration	Inline‑3/inline‑4 2‑Stroke (carbureted or EFI, depending on year)
Common Models	75/90/115/125HP 2‑Stroke families
Advantages	Good power‑to‑weight, broad parts availability, versatile for fishing and general duty
Notes	Carb vs EFI components differ; gearcase ratios and ignition modules vary by model and year—verify with serial.

V6 High Output (Approx. 135–300HP)

Feature	Description
Configuration	V6 2‑Stroke (carb, EFI, or Optimax DFI; 2.5L and 3.0L families)
Common Models	135/150/175/200/225/250/300HP Mercury 2‑Stroke and Optimax variants
Advantages	Strong top‑end output, robust gearcases, wide aftermarket support
Notes	EFI vs Optimax fuel/air systems are not interchangeable; many sensors, pumps, and controls are platform‑specific. Confirm displacement (2.5L vs 3.0L) and serial range.

Routine Maintenance & Service Parts

Intervals below are general guidelines. Always follow your engine’s official service manual and local operating conditions.

Item	Interval*	Remarks	Parts Link
Gear oil (lower unit)	Every 100 hours or annually	Inspect for water intrusion/metal; replace seals if contamination is present.	Mercury Lower Unit Seal Kits
Spark plugs	Every 100 hours or annually	Verify correct heat range and gap; replace if fouled or worn.	Spark Plug
Fuel filter / water‑separating filter	Every 100 hours or annually	Drain or replace more often with ethanol fuel or dirty fuel sources.	Fuel Filters
Water pump impeller / kit	Every 200 hours or 2 years	Replace sooner if weak tell‑tale stream or overheat alarms occur.	Mercury Water Pump Repair Kits
Anodes (internal/external)	Inspect every 50 hours; replace when 50% depleted	Use material suited to your waters (fresh, brackish, or salt).	Anodes
Oil injection system (if equipped)	Inspect annually	Check pump operation, lines, and screen; if pre‑mix, follow manual‑specified ratio.	Mercury Outboard Parts
Propeller & hub	Inspect each outing; remove and grease spline seasonally	Check for fishing line at the seals and bent blades causing vibration.	Propellers

Frequently Used Parts Categories

Routine Service — Mercury Water Pump Repair Kits
Cooling System — Water Pump Impeller Rebuild Kits
Fuel System — Fuel Filters
Ignition / Electrical — Starters
Corrosion Protection — Anodes
Lower Unit / Sealing — Mercury Lower Unit Seal Kits
Propulsion — Propellers

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale or overheat alarm	Inspect intake screens, thermostat, and impeller; look for debris or sand.	Water pump kit, thermostat, intake screen
Poor acceleration / power loss	Verify fuel quality, replace filters, inspect spark plugs; check for air leaks at fuel lines/bulb.	Fuel filter, spark plugs, fuel lines/bulb, fuel pump
Hard starting / rough idle	Prime bulb firm, confirm choke/enrichment operation, inspect plugs and idle settings.	Spark plugs, enrichment/choke components, starter, intake gaskets
Excessive smoke (2‑Stroke)	Confirm correct oil ratio or oil injection operation; check thermostat (cold running) and fuel quality.	Oil injection pump/lines, thermostat, spark plugs
Gearcase noise or metal in gear oil	Drain gear oil, inspect for water; check prop shaft for fishing line; pressure test case.	Lower unit seal kit, bearings, prop shaft seals

FAQs

Are parts interchangeable between different years or platforms?

Some components interchange within the same engine family and serial range, but many items differ between carb, EFI, and Optimax DFI systems, as well as between 2.5L and 3.0L V6 platforms. Always confirm by serial number before ordering.

When should the impeller be replaced?

Inspect annually and replace about every 1–2 seasons, sooner if the tell‑tale stream weakens, you ingest sand/debris, or an overheat occurs.

How often should gear oil be changed?

At least once per season or every 100 hours. If you see milky oil (water) or metal flakes, address seals and internal wear before further use.

What information helps confirm part compatibility?

Provide the engine serial number, model designation, horsepower, shaft length, and fuel system type (carb/EFI/Optimax). Photos of the nameplate and the part needed also help.

Ready to find the right parts? Browse the main Mercury collection by horsepower, year, and model to locate compatible components for your engine.

Shop Mercury Outboard Parts

If you’re unsure about your model, send us a photo of the nameplate and the part you need and we’ll help verify compatibility.