Yamaha 4-Stroke 375HP Outboard Marine Engine Parts

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This page is dedicated to Yamaha 4-Stroke 375HP outboard engines. Use it to find compatible parts, routine service information, maintenance tips, common replacement items, and troubleshooting guidance. You can also browse the main Yamaha collection. Scroll to the bottom of this 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/section.

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How to Identify Your 375HP Model

Nameplate location: Look on the starboard side of the transom bracket for the model/serial plate. The same information is also on an engine label under the cowling.
Reading the code: Yamaha 4-stroke model codes begin with an “F” (e.g., F350, XTO). The characters that follow indicate horsepower and options; suffix letters/numbers denote shaft length, control type, and production revision/year.
Shaft length/control: Suffixes commonly identify 25" or 30" shafts and mechanical vs. digital (DEC/DBW) controls. Match these details when selecting rigging and service parts.
Platform differences: High-output Yamaha 4-strokes in the 350–450 HP class are V8 designs. Many wear items are platform-specific—confirm fit by model code and serial number.

Engine/Platform Overview

Yamaha Offshore V8 4‑Stroke Platform (F350 / XTO family)

Feature	Description
Configuration	V8 EFI 4-stroke, DOHC, electronically controlled fuel injection; built for heavy offshore loads and high thrust.
Common Models	Examples include F350 V8 and XTO Offshore variants (425/450). 375 HP calibrations may exist in select applications/markets—verify using your exact model code.
Advantages	Strong mid‑range torque, robust charging capacity, and offshore‑grade cooling/corrosion protection. Digital control options available on many models.
Notes	Service schedules typically follow Yamaha’s 20‑hour initial and 100‑hour recurring intervals. Some filters, anodes, and rigging items are shared across big‑bore platforms, but gaskets, cooling parts, and gearcase components are model‑specific—confirm by model code and serial.

Routine Maintenance & Service Parts

Intervals below are general guidelines for Yamaha 4‑stroke offshore engines. Always follow the official Yamaha service manual for your exact model, environment, and usage.

Item	Interval*	Remarks	Parts Link
Engine oil + filter	Every 100 hours or annually	Use FC‑W marine oil grade per manual (e.g., 10W‑30/5W‑30). Replace filter at each oil change; warm engine before draining.	Yamaha Service & Maintenance Kits
Gear oil (lower unit)	Every 100 hours or annually	Inspect for water intrusion/metal. Replace drain gaskets; pressure test if oil is milky.	Yamaha Lower Unit Seal Kits
Spark plugs	Inspect 100 hours; replace 300 hours or as needed	Check gap and condition; replace if fouled or worn.	Spark Plugs
Fuel filters (primary/engine)	Every 100 hours or sooner with poor fuel	Replace engine filter and any 10‑micron water‑separating filter; purge water from bowl regularly.	Fuel Filters
Water pump impeller/kit	Annually or 200 hours	Renew impeller; inspect wear plate, cup, key, and seals. Critical for offshore reliability.	Yamaha Water Pump Repair Kits
Anodes (external/internal)	Inspect every 50–100 hours; replace when 50% depleted	Choose alloy for water type (zinc/aluminum/magnesium). Maintain clean electrical bonds.	Yamaha Anodes
Propeller & hub service	Inspect at 100 hours; as needed	Check blades for nicks/bends; remove prop to clear line; grease shaft; verify pitch for load.	Yamaha Propellers
Thermostats	200–300 hours or 2 years	Replace if running cold, overheating at idle, or with scale/corrosion present.	Yamaha Outboard Parts

*Follow the break‑in and 20‑hour service if applicable, then 100‑hour/annual intervals unless your Yamaha manual specifies otherwise.

Frequently Used Parts Categories

Routine Service: Yamaha Service & Maintenance Kits
Cooling System: Yamaha Water Pump Repair Kits
Fuel System Filtration: Fuel Filters
Propellers & Hubs: Yamaha Propellers
Corrosion Protection: Yamaha Anodes
Lower Unit Seals & Hardware: Yamaha Lower Unit Seal Kits
Ignition / Electrical: Spark Plugs and Starters

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale stream or overheat alarm	Inspect intake screens for blockage; verify impeller condition; test thermostats; confirm correct anodes and no heavy scale.	Water pump repair kit, thermostat(s), intake screen, anodes
Poor acceleration or power loss	Check propeller for damage/ventilation; confirm fresh fuel; replace fuel filters; inspect/replace spark plugs; verify engine height/trim.	Propeller, fuel filter(s), spark plugs
Hard starting or rough idle	Confirm battery voltage and cable integrity; prime fuel system; check for air leaks; inspect plugs and fuel filters.	Spark plugs, fuel filter(s), battery cables/terminals
Gearcase noise or metal in gear oil	Drain oil and inspect; replace drain gaskets; check for water intrusion; evaluate prop shaft seals and bearing condition.	Gear oil, lower unit seal kit, bearings
Trim/tilt slow or inoperative	Verify battery charge; inspect relays/connections; check fluid level and for air in system.	Trim motor, relays, hydraulic fluid

FAQs

Are parts interchangeable between different years or platforms?

Many big‑bore Yamaha 4‑strokes share service items, but gaskets, cooling components, sensors, rigging, and gearcase parts can be platform‑ and year‑specific. Always confirm with your full model code, serial number, and shaft length.

When should I replace the water pump impeller?

As a rule of thumb, replace the impeller annually or every 200 hours—sooner if you operate in sandy, silty, or weedy water, or if tell‑tale flow is weak. Offshore users often replace it pre‑season for peace of mind.

How often should lower unit gear oil be changed?

Change gear oil every 100 hours or annually. If the drained oil appears milky (water contamination) or has metal flakes, service seals and inspect internal components before further use.

What information do you need to confirm part compatibility?

Please provide the complete Yamaha model code (including suffix), serial number, shaft length, and control type (mechanical vs. digital). Photos of the nameplate and the part you’re replacing also help ensure an exact match.

Ready to find the right parts? Browse the main Yamaha collection by horsepower, year, and model to locate compatible service items and components.

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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.