Mercury 2-Stroke 55HP Outboard Parts

(38 products)

This page is dedicated to Mercury 2-Stroke 55HP outboard engines. Use it to find compatible parts and practical service information. Below you’ll find maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main Mercury collection any time. Scroll to the bottom of this page to start browsing parts tailored to this engine, and remember that on the collection page you can use the Filter & Sort controls to narrow results by horsepower, year range, and part category.

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How to Identify Your 55HP Model

Locate the nameplate/serial sticker on the transom bracket (starboard clamp bracket) or swivel bracket. Record the full serial number and any model code shown.
Model code suffixes often indicate shaft length (S/L/XL), starting/controls (manual/electric, tiller/remote), and sometimes market region. Note these details when searching parts.
Mercury 55HP in this class is typically a 3‑cylinder carbureted 2‑stroke. Some units used oil‑injection while others require premix—verify which system your engine has before ordering fuel/oiling components.
Parts compatibility can vary across serial ranges. Always confirm your serial range before purchasing ignition, carburetor, gearcase, or cooling parts.

Platform Overview

Mercury 55HP Inline‑3 2‑Stroke

Feature	Description
Configuration	Inline‑3, carbureted 2‑stroke outboard; manual or electric start; tiller or remote control variants.
Common Models	Mercury “55 (3 CYL.)” 2‑stroke models across multiple serial ranges, with Mariner equivalents sharing many hard parts.
Advantages	Light weight, strong mid‑range torque, simple carburetion, widely available service parts.
Notes	Many components interchange with 50/60HP 3‑cyl families. Water pump kits and gearcase seals are shared across popular serial ranges. Verify serial and oiling system (premix vs. oil‑injected) before ordering.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use. Always follow the procedures and schedules in your official service manual.

Item	Interval*	Remarks	Parts Link
Gear oil (lower unit)	Every 100 hrs or annually	Inspect for water or metal; replace drain/vent seals if needed.	Mercury Lower Unit Seal Kits
Spark plugs	100 hrs or annually	Replace fouled/worn plugs; verify heat range and gap per manual.	Spark Plug
Fuel filter (inline/under‑cowl)	100 hrs or as needed	Replace more often with poor fuel quality or storage issues.	Fuel Filters
Water pump impeller/kit	Every 2–3 seasons or 200 hrs	Essential for proper cooling; replace sooner if weak telltale or overheat.	Mercury Water Pump Repair Kits
Anodes (zinc/aluminum/magnesium)	Seasonally; more often in salt/brackish	Replace when 50% consumed; match anode alloy to your water type.	Anodes
Fuel pump (diaphragm/assembly) check	Inspect at 100–200 hrs	Look for hard starting or starvation at WOT; service/replace if weak.	Fuel Pumps
Carburetor clean/rebuild (as needed)	As symptoms arise or during storage recommission	Resolve surging, lean sneeze, or rich idle; renew gaskets/needles.	Carburetor
Oil system (2‑stroke)	Each fill‑up (premix) / 100 hrs (injection check)	Premix typically 50:1 unless specified otherwise. If oil‑injected, inspect tank, lines, and pump operation.	Mercury Outboard Parts

Frequently Used Parts Categories

Routine Service: Mercury Outboard Parts
Cooling System: Mercury Water Pump Repair Kits
Fuel System – Filters: Fuel Filters
Fuel System – Pumps: Fuel Pumps
Ignition/Electrical: Electrical Items
Gearcase & Seals: Mercury Lower Unit Seal Kits
Propulsion & Appearance: Propellers • Decals

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak telltale or overheat alarm	Debris at intake screens; kinked telltale hose; worn impeller; stuck thermostat	Water pump kit/impeller, thermostat, intake screen
Poor acceleration / power loss	Prop damage or wrong pitch; clogged fuel filter; weak fuel pump; dirty carb jets	Fuel filter, fuel pump/diaphragm, carburetor kit, propeller
Hard starting / rough idle	Old fuel; fouled plugs; choke/enrichener not operating; vacuum leaks	Spark plugs, carb gaskets/needles, fuel lines
Excessive smoke (2‑stroke)	Incorrect premix ratio; stuck oil‑injection check (if equipped); prolonged cold‑idle	Spark plugs, fuel/oil lines, reed/carb service
Gearcase noise or metal in oil	Low or milky gear oil; damaged seals; fishing line at prop shaft	Lower unit seal kit, drain/vent seals, prop shaft seal

FAQs

Are parts interchangeable between different years or platforms?

Many 55HP inline‑3 2‑stroke parts interchange with 50/60HP siblings, but changes across serial ranges can affect ignition, carburetion, and gearcase components. Always confirm by serial number before ordering.

When should I replace the impeller?

For recreational use, replace the water pump impeller every 2–3 seasons or ~200 hours, sooner if you notice a weak telltale, overheat warnings, or if the engine has ingested sand or silt.

How often should the lower unit gear oil be changed?

Change gear oil annually or every 100 hours, whichever comes first. Inspect for milky oil (water intrusion) or metallic debris and address seal or bearing issues if found.

What information do you need to confirm part compatibility?

Provide the engine serial number, model code, shaft length (S/L/XL), control type (tiller/remote; manual/electric start), and whether your engine is premix or oil‑injected. Photos of the nameplate and the part in question also help.

Ready to find parts for your Mercury by horsepower, year, and model? Browse our main Mercury outboard collection and use the filters to narrow your results.

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