Yanmar 4-Stroke 29HP Marine Engine Parts

(2 products)

This page is for Yanmar 4-Stroke 29HP marine engines. It helps you quickly find compatible parts and practical service information, including maintenance tips, common replacement items, and troubleshooting guidance. You can also browse the main Yanmar collection. Scroll to the bottom of this page 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.

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How to Identify Your 29HP Model

Find the nameplate/serial plate on the engine: commonly on the cylinder head cover or near the heat exchanger bracket; gearbox or saildrive plates are on their housings.
Model code basics: for this power class, many engines are “3YM30” (3-cylinder, ~29 HP). Suffixes and companion tags indicate gearbox (KM2P‑1) or saildrive (SD20) options.
Configuration cues: a compact inline 3‑cylinder, 4‑stroke diesel with fresh‑water cooling via heat exchanger and a raw‑water pump.
Record the full model code, serial number, and whether you have a gearbox or saildrive to confirm parts compatibility.

Engine Overview

Yanmar 3YM30 (~29 HP)

Feature	Description
Configuration	Inline 3‑cylinder, 4‑stroke, direct‑injection diesel; fresh‑water cooled via heat exchanger with raw‑water pump; 12V electric start.
Common Models	3YM30 with KM2P‑1 reduction gearbox or SD20 saildrive (year ranges commonly from the mid‑2000s onward).
Advantages	Compact, efficient, and widely supported; strong low‑to‑mid torque; simple routine service items.
Notes	Mixing elbows, raw‑water impellers, belts, anodes, and fuel filters are typical wear items. Verify gearbox vs saildrive when ordering drivetrain parts.

Routine Maintenance & Service Parts

Intervals below are general guidelines for typical recreational use. Always follow the official Yanmar service manual and the maintenance schedule for your specific engine, gearbox, or saildrive.

Item	Interval*	Remarks	Parts Link
Engine oil & oil filter	Every 100 hours or annually	Use marine‑rated diesel oil; replace filter at each oil change.	Yanmar Oil filters
Gearbox/Saildrive oil	100–200 hours or annually (per unit spec)	Check the KM2P‑1 or SD20 specification; change sooner if contaminated.	Yanmar Service & Maintenance Kits
Primary/secondary fuel filters	Every 100 hours or annually	Replace both filters; bleed air from system after service.	Yanmar Fuel filters
Raw‑water pump impeller/kit	Every 200 hours or 2 years	Inspect each season; replace sooner if water flow is weak or vanes are cracked.	Water Pump Impeller Rebuild Kits
Heat‑exchanger/saildrive anodes	Inspect 50 hours; replace when 50% depleted	More frequent checks in warm or brackish water.	Anodes
V‑belt / alternator belt	Inspect every 100 hours; replace as needed or annually	Check tension and glazing; replace if cracked or noisy.	Belt
Thermostat & cooling hoses	2–3 years or as needed	Replace if temperature control is erratic or hoses are soft/cracked.	Hoses
Glow plugs (diesel)	Test seasonally; replace as needed	If cold‑starts are difficult, test each plug and the relay circuit.	Yanmar

Common Symptoms & Quick Checks

Symptom	Check First	Related Parts
Overheat alarm / high temperature	Raw‑water strainer blockage, intake screen fouling, impeller wear, belt tension, coolant level, heat‑exchanger scaling.	Water pump kit, thermostat, anodes, hoses, V‑belt.
Hard starting / rough idle (diesel)	Fuel quality/level, primary & secondary filters, air leaks on suction side, bleed procedure, glow plug power and relay.	Fuel filters, fuel pump, glow plugs, battery/charging components.
Poor acceleration / power loss	Restricted mixing elbow, clogged filters, throttle cable travel, hull/prop fouling.	Mixing elbow & gasket, fuel filters, hoses.
Charging light on / low voltage	V‑belt slip, alternator connections, battery state of charge/health.	Alternator belt, alternator, regulator, wiring.
Gearbox/saildrive noise or milky oil	Oil level and condition, water intrusion via seals, alignment, recent prop strike.	Seals, bearings, gear oil, engine/gearbox mounts.

FAQs

Are parts interchangeable between different years or platforms?

Many service items (filters, belts, anodes) are shared across years, but exhaust elbows, pumps, and electrical components can vary. Confirm the full engine model (e.g., 3YM30) and whether you have a KM2P‑1 gearbox or an SD20 saildrive before ordering.

When should the raw‑water impeller be replaced?

As a rule of thumb, replace every 200 hours or every 2 years (whichever comes first). Replace sooner if the water flow is weak, the overheat alarm triggers, or the impeller shows cracking or set.

How often should gearbox or saildrive oil be changed?

Typically every season or 100–200 hours, depending on the specific unit. If the oil appears milky, change it immediately and inspect seals for water intrusion.

What information helps confirm part compatibility?

Provide the full engine model and serial number, plus your drivetrain type (KM2P‑1 gearbox or SD20 saildrive). Photos of the nameplate and the existing part help us verify the correct replacement.

Ready to find the right parts? Browse the main Yanmar collection and narrow by horsepower, year, and model to get the best match for your 29HP 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.