Johnson 2-Stroke 6-20HP Outboard Marine Engine Parts

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For Johnson 2-Stroke 6-20HP outboard engines, this page helps you find compatible parts and practical service information. Inside you’ll find maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main Johnson/Evinrude/OMC collection. Scroll to the bottom of the page to start browsing parts for 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 6-20HP Model

Find the nameplate/serial plate on the transom bracket (usually port side) or on the swivel bracket. Record the model number, serial, and any suffix letters.
Decode the suffix: common letters indicate shaft length (S = 15 in, L = 20 in, X = 25 in), and features like electric start (E) or tiller/remote control variants.
These small Johnson 2-strokes are carbureted and typically twin‑cylinder. Verify year and feature codes to ensure correct impeller kits, plugs, and carb parts.
If unsure, match parts by model number and year rather than horsepower alone, as some components changed across production runs.

Engine Overview

Small Carbureted Inline Twin (6–20HP)

Feature	Description
Configuration	Carbureted 2‑stroke, reed‑valve inline twin (pull or electric start), mechanical fuel pump, premix fuel/oil on most models.
Common Models	Johnson 6HP, 8HP, 9.9HP, 15HP, and 20HP 2‑Stroke families across multiple years.
Advantages	Lightweight, simple to service, strong low‑to‑mid torque for small boats and tenders.
Notes	Many service parts overlap within the 9.9/15HP families; verify year/code for impeller, thermostat, and carb kits. Shaft length and start/control options can affect rigging parts.

Routine Maintenance & Service Parts

Intervals below are general guidelines; always follow the official service manual for your exact model and use conditions.

Item	Interval*	Remarks	Parts Link
Gear oil (lower unit)	Every 100 hrs or annually	Inspect for water/milkiness; replace seals if contamination is found.	Lower Unit Seal Kits
Spark plugs	Inspect 50 hrs; replace 100 hrs or annually	Check heat range and gap per manual; fouling often indicates rich mix or low running temp.	Spark Plugs
Fuel filter / in‑line filter	Inspect 50 hrs; replace 100 hrs	Replace sooner if debris or phase‑separated fuel is suspected.	Fuel Filters
Water pump impeller/kit	Every 2 seasons or 100 hrs	Critical for cooling; replace sooner if weak tell‑tale or overheat alarm occurs.	Johnson/Evinrude/OMC Water Pump Repair Kits
Thermostat	Inspect annually; replace 2–3 years	Stuck‑open stats cause cold running and plug fouling; stuck‑closed can overheat.	Johnson/Evinrude/OMC Outboard Parts
Anodes (corrosion protection)	Inspect 50 hrs; replace when 50% depleted	Use alloy suitable for your water (fresh, brackish, or salt).	Johnson/Evinrude/OMC Anodes
Fuel lines & connectors	Inspect annually	Replace ethanol‑hardened hoses and worn quick‑connects to prevent air leaks.	Fuel Connector
Carburetor service (clean/rebuild)	As needed (symptoms or every 2–3 seasons)	Address varnish, clogged jets, and dried gaskets; sync idle mixture after service.	Carburetors & Kits
Fuel/oil premix (2‑stroke)	Every fill‑up	Most models use 50:1 (gasoline:TC‑W3 oil). Verify your model’s specification.	Johnson/Evinrude/OMC Outboard Parts

Frequently Used Parts Categories

Routine Service: Johnson/Evinrude/OMC Service & Maintenance Kits
Cooling System: Water Pump Repair Kits
Fuel System – Filters: Fuel Filters
Fuel System – Pumps: Fuel Pumps
Ignition / Electrical: Electrical Items
Lower Unit / Seals: Lower Unit Seal Kits
Propulsion & Protection: Propellers and Propeller Guards

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale stream or overheat alarm	Inspect intake screens for debris; verify impeller condition and thermostat function.	Water pump repair kit, thermostat, intake screen grommets
Hard starting / rough idle	Prime fuel system, check for stale fuel, verify choke/primer operation, inspect plug gap.	Carburetor rebuild kit, fuel filter, spark plugs
Poor acceleration or power loss	Compression test, check ignition spark, examine prop for damage or over‑pitch.	Spark plugs, carb kit, fuel pump, propeller
Excessive smoke/oily residue	Confirm premix ratio, verify thermostat is not stuck open causing cold running.	Spark plugs, thermostat
Gearcase noise or metal in gear oil	Drain/inspect gear oil; check for water intrusion and seal wear.	Lower unit seal kit, shims/bearings (as required)

FAQs

Are parts interchangeable between different years or platforms?

Some items, like spark plugs and anodes, may span multiple years, but cooling and carburetor parts can change with revisions. Always confirm by model number, year, and shaft/control options before ordering.

When should the impeller be replaced?

As a rule of thumb, replace the impeller every 2 seasons or about 100 hours. If the tell‑tale weakens or the engine overheats, service the water pump immediately.

How often should I change the gear oil?

Change lower unit gear oil every 100 hours or annually, and whenever you see contamination (water/milky appearance) or after prop‑strike events.

What information do you need to confirm part compatibility?

Provide the full model number, serial number, horsepower, shaft length, and whether the motor is pull or electric start. Photos of the nameplate and the part being replaced are very helpful.

Ready to find the right parts? Browse the main Johnson/Evinrude/OMC collection by horsepower, year, and model to locate compatible components for your 2‑stroke 6–20HP outboard.

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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.