Mercury 4-Stroke 15HP Outboard Engine Parts

(68 products)

This page is tailored for Mercury 4-Stroke 15HP outboard engines. Use it to find compatible parts, routine maintenance guidance, and quick troubleshooting tips. You can also browse our main Mercury collection, and at the bottom of this page you’ll find links to start browsing parts for this engine. On the collection pages, use the Filter & Sort controls to narrow results by horsepower, year range, and part category.

Browse All Mercury Parts

How to Identify Your 15HP Model

Locate the serial/model plate on the transom bracket or swivel bracket. Record the full serial number and any suffix.
Model codes/suffixes indicate shaft length (e.g., short/long/extra-long), start type (manual/electric), and options (e.g., tiller or remote). Match these when selecting parts.
This 15HP FourStroke family commonly uses EFI and an inline 2‑cylinder configuration. Confirm whether your unit is manual- or electric‑start, and note shaft length for water‑pump/shift‑linkage related parts.
If unsure, compare the cowling decals and the serial plate data; both should align with “15 FourStroke EFI” within the 15/20 EFI family.

Engine Overview

Mercury 15 FourStroke EFI (15/20 EFI Family)

Feature	Description
Configuration	Inline‑2, EFI, FourStroke; displacement ~333 cc, computer‑controlled ignition and protection features.
Common Models	15 FourStroke EFI in manual or electric start variants; short/long/extra‑long shaft options; tiller or remote control. (Examples may include manual/electric designations and shaft length suffixes.)
Advantages	Quiet operation, low fuel consumption, smooth idle from EFI, compact twin‑cylinder layout for small craft.
Notes	Many service parts (water pump kit, anodes, plugs) are shared across the 15/20 EFI family; verify shaft length and start type before ordering.

Routine Maintenance & Service Parts

Intervals below are typical guidelines for small EFI FourStroke outboards. Always confirm procedures and intervals in your official service manual and operate with clean, stabilized fuel.

Item	Interval*	Remarks	Parts Link
Engine oil & filter	Every 100 hours or annually	Use FC‑W 10W‑30 (or as specified). Warm engine before draining for best results.	Oil Filters
Gear oil (lower unit)	Every 100 hours or annually	Inspect magnet for metal and check for water intrusion (milky oil). Replace seals if needed.	Mercury Lower Unit Seal Kits
Spark plugs	Inspect at 100 hours; replace ~300 hours or 3 years	Verify correct heat range and gap; replace sooner if fouled or corroded.	Spark Plugs
Fuel filter / water‑separating filter	Inspect at 100 hours or each season	Drain water as required; replace element if contaminated or restricted.	Fuel Filters
Water pump impeller / kit	2–3 seasons (or sooner with sand/silt use)	Weak tell‑tale or overheat alarms often indicate a worn impeller or blocked intake.	Mercury Water Pump Repair Kits
Anodes (external)	Inspect every 100 hours; replace when ~50% consumed	Do not paint anodes. Use the correct alloy for your water (fresh/brackish/salt).	Anodes

*Intervals are general recommendations; always follow the latest Mercury service literature for your exact model and usage.

Frequently Used Parts Categories

Routine Service Kits: Service & Maintenance Kits
Cooling System (impellers & kits): Mercury Water Pump Repair Kits
Fuel System (filters, pumps): Fuel Filters | Fuel Pumps
Ignition / Electrical (sensors, charging, starting): Sensors | 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 stream / overheat alarm	Inspect intake screens for blockage; confirm thermostat opens; evaluate impeller age.	Water pump repair kit, thermostat, intake screens, anodes (for corrosion control)
Hard starting / rough idle	Use fresh fuel; check fuel filter for water; verify spark plug condition and gap.	Fuel filters, spark plugs
Poor acceleration / power loss	Check prop condition (dings/hub); verify gear oil level; confirm no fuel restriction.	Propeller, fuel filter, gearcase seal kit (if oil loss found)
Gearcase noise / metal in gear oil	Drain and inspect oil; look for water intrusion; inspect prop shaft for fishing line at seals.	Lower unit seal kit, propeller hardware

FAQs

Are parts interchangeable between different years in the 15/20 EFI family?

Many service parts (plugs, anodes, impeller kits) carry over, but changes in shaft length, start method, and running changes can affect fit. Verify by serial number and model suffix before ordering.

When should the water‑pump impeller be replaced?

Inspect every season and replace about every 2–3 years, or immediately if water flow is weak, you run in sandy/silty water, or you observe overheat warnings.

How often should I change lower‑unit gear oil?

Typically every 100 hours or annually. If the oil appears milky, change it immediately and inspect/replace seals to address water intrusion.

What information do I need to confirm part compatibility?

Have the full serial number, model code/suffix (shaft length and start type), and confirm whether your engine is tiller or remote control. Photos of the nameplate and the part being replaced are very helpful.

Ready to find parts for your Mercury 15 FourStroke? Browse our main Mercury collection and use the filters to narrow by horsepower, year range, and category.

Browse All Mercury Parts

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