Johnson 2-Stroke 4.5HP Outboard Marine Engine Parts

(6 products)

For Johnson 2-Stroke 4.5HP outboard engines, this page helps you quickly find compatible parts and essential service information. Below you’ll find maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main Johnson/Evinrude/OMC collection at any time. Scroll to the bottom of the page to start browsing parts for this engine, and remember you can use the “Filter & Sort” controls on the collection page to narrow by horsepower, year range, and part category/section.

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How to Identify Your 4.5HP Model

Find the nameplate/serial plate on the transom bracket or swivel bracket. It lists the model number and serial number.
Read the full model code and suffix: letters often indicate shaft length (short/long) and other features; the serial can help pinpoint the production year.
Confirm the stroke type: these are carbureted 2-stroke models requiring proper fuel/oil mix; check the cowl decals and the owner’s manual.
Measure shaft length (approx. 15 in short, 20 in long) because propeller and gearcase parts may vary by shaft length.

Platform Overview

Johnson 4.5HP 2‑Stroke (Early 1980s Era)

Feature	Description
Configuration	Small-displacement, carbureted 2-stroke outboard; portable, typically tiller-steer and manual start.
Common Models	Johnson 4.5HP 2-stroke models (early 1980s). Verify by full model and serial number for exact parts.
Advantages	Lightweight, simple maintenance, easy to transport, reliable low-speed maneuvering.
Notes	Some wear parts interchange with 4–6HP families, but impeller, propeller, and gearcase items can vary by year and shaft length—confirm by model/serial.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use. Always follow the official service manual for your exact model and operating conditions.

Item	Interval*	Remarks	Parts Link
Gear Oil (Lower Unit)	Every season or 100 hours	Check for water intrusion and metal debris; replace drain plug gaskets as needed.	Johnson/Evinrude/OMC Outboard Parts
Spark Plugs	100 hours or annually	Inspect, clean, and gap; replace if fouled or worn.	Spark plug
Fuel Filter / Inline Filter	Inspect every 50 hours; replace as needed	Replace sooner if fuel contamination or storage issues are suspected.	Fuel Filters
Water Pump Impeller / Kit	Every 2–3 seasons (or sooner with weak telltale)	Critical for cooling; replace more often in sandy/silty water.	Johnson/Evinrude/OMC Water Pump Repair Kits
Anodes (Corrosion Protection)	Inspect every 50 hours; replace when 50% worn	Match anode material to your water type (fresh, brackish, salt).	Johnson/Evinrude/OMC Anodes
Propeller Inspection	Every 50 hours; before/after season	Check for dings and bent blades that can cause vibration and reduced thrust.	Johnson/Evinrude/OMC Propellers
2‑Stroke Fuel/Oil Mix	Each refuel	Use the mix ratio specified in your owner’s manual; use fresh gasoline and TC‑W3 marine oil.	Johnson/Evinrude/OMC Outboard Parts

*Intervals are general guidelines and may vary by model year and usage.

Frequently Used Parts Categories

Routine Service Kits — Johnson/Evinrude/OMC Service & Maintenance Kits
Cooling System — Water Pump Repair Kits
Gearcase & Seals — Lower Unit Seal Kits
Ignition / Electrical — Electrical Items
Fuel System — Fuel Filters
Propulsion — Johnson/Evinrude/OMC Propellers
Corrosion Protection — Johnson/Evinrude/OMC Anodes

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak telltale or overheat alarm	Inspect intake screen for blockage; verify impeller condition; confirm thermostat operation.	Water pump kit, impeller, thermostat, intake screen/grommets
Poor acceleration or power loss	Check for damaged propeller, fouled plugs, stale fuel, and restricted fuel filter.	Propeller, spark plugs, fuel filter, carb gaskets/cleaning kit
Hard starting or rough idle	Verify choke/primer function, plug gap, and for air leaks at fuel lines/bulb.	Spark plugs, fuel hoses, primer bulb, gaskets
Excessive smoke (2-stroke)	Confirm correct fuel/oil mix ratio; check for misfire and thermostat stuck open.	Spark plugs, thermostat, fuel/oil mix supplies
Gearcase noise or metal in gear oil	Drain and inspect gear oil; look for water intrusion and damaged seals/bearings.	Lower unit seals, bearings, drain plug gaskets, gear oil

FAQs

Are parts interchangeable between different years or related 4–6HP platforms?

Many wear items are shared across small Johnson/Evinrude models, but cooling, propeller, and gearcase parts can vary by year, shaft length, and specific sub-model. Always confirm by full model and serial number.

When should I replace the impeller?

For light recreational use, replace the impeller every 2–3 seasons. In sandy/silty water, or if the telltale is weak or intermittent, service it sooner using a complete water pump kit.

How often should the lower unit gear oil be changed?

At least once per season or every 100 hours. Inspect for milky appearance (water) or metal particles, which indicate seal or gear wear requiring further service.

What information do you need to confirm parts fitment?

Please provide the full model number, serial number, shaft length (short/long), and any notable features (manual/electric start). Photos of the nameplate and the part needed are very helpful.

Ready to shop? Browse the main Johnson/Evinrude/OMC collection and use “Filter & Sort” to refine by horsepower, year, and model.

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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.