Tohatsu 4-Stroke 100HP Outboard Marine Engine Parts

(15 products)

This page is dedicated to Tohatsu 4-Stroke 100HP outboard engines. Use it to find compatible parts and service information, including maintenance tips, common replacement parts, and troubleshooting guidance. You can also browse the main Tohatsu collection, and at the bottom of this page you’ll find a quick way to start browsing parts for this engine. On the collection page, use the “Filter & Sort” controls to narrow results by horsepower, year range, and part category/section.

Browse All Tohatsu Parts

How to Identify Your 100HP Model

Nameplate/serial plate: Typically on the starboard transom bracket or swivel bracket. Record the model designation and serial number.
Reading the code: Tohatsu mid‑range 4‑stroke models often use an “MFS” prefix (e.g., MFS100 series). Suffix letters indicate shaft length (S/L/XL), control type (remote vs tiller), and other options.
4‑Stroke cues: Look for an engine oil dipstick and oil filter canister. EFI labeling and an electric lift pump are common on modern 100HP models.
Platform differences: Many maintenance parts are shared across the 75/90/100/115 mid‑range family. Always confirm with your exact model code and serial for parts compatibility.

Engine Overview

Tohatsu 100HP 4‑Stroke (Mid‑Range Platform)

Feature	Description
Configuration	Inline‑4, 4‑stroke EFI outboard; electronic ignition; remote or tiller control depending on model suffix.
Common Models	100HP EFI 4‑stroke models (e.g., MFS100 series). Shaft lengths commonly L (20") or XL (25").
Advantages	Good fuel economy and quiet operation; broad mid‑range torque; straightforward routine service.
Notes	Many service parts cross over with 90/115HP of the same generation. Verify by serial and model code before ordering.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use. Always follow the schedule and specifications in your official Tohatsu service manual.

Item	Interval*	Remarks	Parts Link
Engine oil + filter	100 hours or annually	Use FC‑W 4‑stroke marine oil; confirm viscosity for climate; replace crush washer if specified.	Oil Filters
Gear oil (lower unit)	100 hours or annually	Check for water/milkiness and metal on drain plug magnet; replace seals if contamination is found.	Tohatsu Outboard Parts
Spark plugs	Inspect 100 hours; replace 200 hours or as needed	Verify heat range and gap for your model code; torque to spec on a cold engine.	Spark Plug
Fuel filter (inline/under‑cowl)	100 hours or annually	Replace more often with ethanol fuel or dirty tanks; add a water‑separating filter if needed.	Fuel Filters
Water pump impeller/kit	2–3 seasons or 200 hours	Shorten interval for sandy/silty use or high temps; replace full kit if wear is found.	Tohatsu Water Pump Repair Kits
Anodes (external & internal)	Inspect 50 hours; replace at ~50% loss	Match alloy to your water (zinc, aluminum, or magnesium). Keep paint off anodes.	Anodes
Propeller & hub	Inspect every 50 hours; replace as needed	Check for dings, bent blades, and hub slippage; remove to clear fishing line; grease shaft splines.	Propellers

*Follow the most conservative recommendation between hours and calendar time, and adjust for severe or commercial duty.

Frequently Used Parts Categories

Routine Service: Oil Filters
Cooling System: Tohatsu Water Pump Repair Kits
Fuel System: Fuel Filters
Ignition / Electrical: Electrical Items
Propulsion: Propellers
Corrosion Protection: Anodes
Gearcase Service: Tohatsu Lower Unit Seal Kits

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak telltale stream or overheat alarm	Inspect intake screens for debris; verify impeller age; check thermostat for sticking.	Water pump kit, thermostat, intake screen cleaning
Hard starting or rough idle	Check battery voltage and connections; replace/inspect spark plugs; verify clean fuel and filter.	Spark plugs, fuel filter, electrical connectors
Poor acceleration or power loss	Inspect propeller for damage or hub slip; check for water in fuel; confirm throttle/shift cable adjustment.	Propeller/hub, fuel filter, control cables
Gearcase noise or metal in gear oil	Check oil level and condition; look for fishing line on prop shaft; pressure test lower unit if water intrusion suspected.	Lower unit seal kit, bearings, shims (as required)

FAQs

Are parts interchangeable between different years or related platforms (90/100/115HP)?

Many routine service parts are shared within the mid‑range family, but changes by year, gearcase, and control options mean compatibility is not guaranteed. Always confirm with the exact model code and serial number before ordering.

When should I replace the water pump impeller?

A common interval is every 2–3 seasons or about 200 hours, sooner for sandy/silty water or if the telltale weakens or the engine overheats. If wear is present, install a full kit (impeller, plate, cup, seals) rather than the impeller alone.

How often should the gear oil be changed?

Typically every 100 hours or annually. Inspect drained oil for milkiness (water) and metal on the plug magnet; address seal or gear issues if contamination is found.

What information do I need to confirm part compatibility?

Provide the model code, serial number, shaft length (S/L/XL), control type (remote/tiller), and any known year range. Photos of the nameplate and the existing part help ensure a match.

Ready to find parts by horsepower, year, and model? Browse the main Tohatsu collection and use the “Filter & Sort” tools to narrow down to your 100HP 4‑stroke.

Shop Tohatsu Outboard Parts

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.