Onan 16-24HP 4-Stroke Marine Engine Parts

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This page is for Onan 16–24HP 4‑Stroke marine engines. It helps you 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 Onan collection. Scroll to the bottom of this page to start browsing parts for this engine, and on the collection page use the Filter & Sort controls to narrow results by horsepower, year range, and part category.

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How to Identify Your 16–24HP Model

Nameplate/serial plate: Look on the blower housing or crankcase area. Record the Model, Spec, and Serial numbers.
Model code: Common examples include P216, P218, and P220 (often with a “G” gasoline suffix). The Spec letter/number can indicate factory options (air cleaner type, governor setup, charging output, choke type).
Fuel/platform details: These 4‑stroke “Performer” engines are air‑cooled twin‑cylinder units typically carbureted for gasoline, with some LP variants. Note manual vs remote choke and 12V vs 24V charging when ordering parts.
Marine installations: If fitted to a genset or auxiliary package, note any remote air intake, enclosure, or exhaust options on the equipment tag.

Engine Overview

Onan Performer Series (P216/P218/P220)

Feature	Description
Configuration	Air‑cooled, OHV, twin‑cylinder 4‑stroke (horizontal layout); carbureted gasoline versions common; some LP variants.
Common Models	P216, P218, P220 (often shown as P216G/P218G/P220G on nameplates). Output typically 16–24 HP depending on model and spec.
Advantages	Simple maintenance, durable construction, strong low‑to‑mid torque for auxiliary/genset use, widely supported service items.
Notes	Parts often vary by Spec code (air cleaner capacity, choke type, regulator output, LP vs gasoline). Verify the full model/spec/serial before ordering.

Routine Maintenance & Service Parts

Intervals below are general guidelines for small 4‑stroke Onan engines. Always follow the maintenance schedule and procedures in your specific service manual.

Item	Interval*	Remarks	Parts Link
Engine oil + filter	Every 50–100 hours or annually	Warm engine before draining; replace filter each oil change; use marine‑appropriate oil grade per manual.	Oil Filters
Air filter element	Inspect 50 hours; replace 200 hours or as needed	Keep cooling/induction paths clean. High‑capacity housings may use different elements.	Air Filters
Spark plugs	Every 100 hours or annually	Check heat range and gap to spec; replace if fouled or worn.	Spark Plugs
Fuel filter (inline)	100 hours or seasonally	Replace sooner if restricted flow or contamination is suspected.	Fuel Filters
Carburetor service (clean/rebuild)	2–3 years, or as symptoms arise	Address hard starting, surging, or poor throttle response; verify choke and governor linkage.	Carburetor
Charging/ignition check	100 hours or seasonally	Inspect wiring, regulator/rectifier output, and battery state of health.	Alternators / Rectifiers
Anodes (if genset has raw‑water components)	Inspect seasonally	Only applicable where a raw‑water circuit or heat exchanger is present. Replace when 50% consumed.	Anodes

*Use the engine’s official manual for exact intervals and specifications.

Frequently Used Parts Categories

Routine Service: Oil Filters, Air Filters, Spark Plugs
Fuel System: Fuel Filters, Carburetor
Ignition / Charging: Alternators, Rectifiers
Starting: Starters, Ignition Switch
Gaskets & Sealing: Gaskets, Oil Seals
Sensing & Protection: Sensors, Anodes

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Hard starting or rough idle	Fuel freshness, inline filter restriction, choke operation, air filter condition, vacuum leaks at carb/manifold.	Fuel filter, spark plugs, carburetor repair kit, intake gaskets.
Surging/hunting at steady RPM	Governor spring/linkage, minor jet/blockage in carb, vacuum leaks, LP supply (if applicable).	Carburetor kit, gaskets, fuel filter.
Overheat or high‑temp shutdown	Blocked cooling fins or shrouds, debris in blower area, poor ventilation in enclosure, faulty temperature switch.	Air filter, cleaning/shroud hardware, temperature switch (sensor).
Low charge or weak battery	Charging output at regulator/rectifier, stator continuity, wiring/grounds, battery health.	Alternator/stator, regulator/rectifier, connectors.
Backfire on decel/shutdown	Lean mixture, air leaks, incorrect idle speed, carbon buildup.	Carburetor kit, gaskets, spark plugs.

FAQs

Are parts interchangeable between different years or Spec codes?

Some service items cross between P216, P218, and P220, but air cleaner size, choke type, charging output, and LP vs gasoline setups can change part selection. Always verify the Model, Spec, and Serial numbers from your nameplate before ordering.

When should I replace the impeller?

These air‑cooled engines typically do not use a raw‑water impeller. If your marine package (e.g., genset with heat exchanger) includes a raw‑water pump, follow the equipment maker’s guideline—often every 1–2 seasons or sooner in sandy/silty water.

How often should I change fuel and engine oil filters?

Inline fuel filters are commonly replaced every 100 hours or each season. Replace the engine oil filter with every oil change (often 50–100 hours or annually), using the viscosity and capacity specified in your manual.

What information do you need to confirm part compatibility?

Please provide the full model (e.g., P216/P218/P220), Spec code, Serial number from the nameplate, fuel type (gasoline or LP), charging voltage (12V/24V), and any marine package options such as remote air cleaner or enclosure.

Ready to find parts by horsepower, year, and model? Browse our main collection and use the Filter & Sort tools to narrow results for your Onan 16–24HP 4‑Stroke engine.

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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.