Tohatsu 8HP 4-Stroke Outboard Marine Engine Parts

(26 products)

This page is tailored for Tohatsu 4‑Stroke 8HP outboard engines. Use it to find compatible parts and service information, including routine maintenance tips, common replacement items, and troubleshooting guidance. You can also browse the main Tohatsu 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.

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How to Identify Your 8HP Model

Serial/ID plate location: typically on the clamp bracket or swivel bracket. Record the full model code and serial number.
Model code basics (examples): MFS8B variants often include suffixes for start/control and shaft length, e.g., MF/EF/EFT/EPT (manual/electric start, tiller or remote), and S/L/UL for 15/20/25 in shafts.
4‑Stroke indicators: oil filler cap and dipstick under the top cowl, separate engine oil and a gearcase with drain/fill plugs.
Platform clue: most 8HP 4‑Stroke Tohatsu models are 2‑cylinder carbureted units that share many service parts with certain 9.8HP siblings.

Engine Overview

Tohatsu 8HP 4‑Stroke (MFS8B family)

Feature	Description
Configuration	Inline 2‑cylinder, 4‑stroke, carbureted; water‑cooled; through‑hub exhaust.
Common Models	MFS8B variants: MF/EF (tiller), EP/EFT/EPT (remote/electric/power tilt depending on suffix); S/L/UL shaft options.
Advantages	Lightweight and simple; good fuel economy; broad parts availability; many service items shared with 9.8B.
Notes	Typical spark plug type NGK DCPR6E with 0.8–0.9 mm gap; gear ratio ~2.08; use FC‑W or API SH/SJ/SL 10W‑30/40 engine oil; verify shaft length and start/control options when ordering parts.

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
Engine oil (4‑Stroke) & filter	Every 100 hrs or annually	Use marine 10W‑30/40 that meets FC‑W or API SH/SJ/SL; change more often for harsh use.	Oil Filters
Gear oil (lower unit)	Every 100 hrs or annually	Inspect for milkiness/metal; replace gaskets; service sooner after impacts or submersion.	Lower Unit Seal Kits
Spark plugs	Inspect 100 hrs; replace 200 hrs or as needed	Clean/inspect and set gap to spec; replace if worn or fouled.	Spark Plugs
Fuel filter(s)	Inspect every 50–100 hrs	Replace at signs of restriction/water; consider water‑separating type for ethanol fuels.	Fuel Filters
Water pump impeller/kit	Annually or every 100 hrs	Replace sooner if weak tell‑tale, overheat alarms, or sand/silt use.	Tohatsu Water Pump Repair Kits
Anodes (sacrificial)	Inspect 50–100 hrs	Replace when ~50–70% consumed; never paint anodes.	Anodes
Propeller & hardware	Inspect each outing	Check for dings, fishing line around shaft; verify nut and cotter pin.	Propellers

Frequently Used Parts Categories

Routine Service: Oil Filters, Impellers, Anodes
Cooling System: Tohatsu Water Pump Repair Kits, Impellers
Fuel System: Fuel Filters, Fuel Connectors
Ignition / Electrical: Spark Plugs, Electrical Items, Starters
Gearcase & Sealing: Tohatsu Lower Unit Seal Kits
Propulsion & Handling: Propellers, Propeller Guards, Outboard Hydrofoil Stabilizers
General Boat Accessories: Boat Accessories

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Weak tell‑tale or overheat alarm	Debris on intake screens; pinched fuel line causing lean run; impeller age; thermostat stuck; verify water level if running in a tank.	Water pump kit, impeller, thermostat, intake screen
Hard starting or rough idle	Fresh 87‑octane fuel; prime bulb firm; choke/enrichment operation; spark plug condition/gap; water in fuel; idle speed only after warm‑up.	Fuel filter, spark plugs, fuel connector/hose, carburetor service
Poor acceleration / power loss	Prop damage or wrong pitch; restricted fuel flow; plug fouling; low compression; excessive hull load/trim.	Propeller, fuel filters, spark plugs, anodes (drag), hydrofoil/trim aids
Gearcase noise or milky gear oil	Drain oil and inspect; water intrusion from failed seals; fishing line on prop shaft; correct torque on drain/fill screws.	Lower unit seal kit, prop shaft seal, drain/fill gaskets, gear oil

FAQs

Are parts interchangeable across 8HP and 9.8HP models?

Many routine service parts (impellers, some seal kits, and filters) are shared across MFS8B and MFS9.8B variants. Always confirm by model code, suffix (start/control), shaft length, and serial number before ordering.

When should I replace the impeller?

As a preventive service, replace the impeller annually or every 100 hours—sooner if you see a weak tell‑tale, overheat warnings, or frequent sand/silt operation.

How often should I change lower unit gear oil?

Change at least every 100 hours or annually. Inspect immediately after an impact or if the engine has been submerged, and replace drain/fill gaskets each service.

What information helps confirm part compatibility?

Provide the full model code (e.g., MFS8B with suffix), serial number, shaft length (S/L/UL), start/control type (manual/electric, tiller/remote), and any known year range or measurements.

Ready to find parts? Browse the main Tohatsu collection and filter by horsepower, year, and model to zero in on compatible 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.