Yanmar · Inboard diesel

Yanmar 3YM30

The 3YM30 is the largest of Yanmar’s YM series (with the 2YM15 and 3YM20): a three-cylinder, naturally aspirated, indirect-injection diesel with fresh-water cooling for smaller sailing yachts, and the successor of the 3GM30. The original 3YM30 makes 21.3 kW (29 hp) at 3,600 rpm from 1.115 l and came with the KM2P-1 gearbox or the SD20 saildrive. The current 3YM30AE keeps the 29 hp but uses a larger 1.266 l block at 3,200 rpm, with the KM2P-1 or the SD25. Filters, thermostat and impeller kit are shared; the raw water pump and its belt are not. This page also covers the two-cylinder 2YM15 (0.57 l, 14 hp) and the three-cylinder 3YM20 (0.854 l, 21 hp), which share a smaller 70 × 74 mm cylinder and never had an AE version. They take the same filters, impeller kit, thermostat, exhaust elbow and glow plugs as the 3YM30, but have their own 6PK alternator belt, gasket set and (2YM15 only) heat exchanger core, and the 3YM20 switched to the AE-type raw water pump at serial E13046.

Manuals & documents

The links go straight to Yanmar. We host no manuals or drawings — the manufacturer’s copy is the current one.

Wear parts & part numbers

PartOEM numberAlso fitsNote
Impeller kit (with gasket)128990-425703,4,5,6,7,8replaces 128990-42200Johnson Pump 09-810B-11,2Same kit on all YM engines: 3YM30, 3YM30AE, 2YM15 and 3YM20 (the 2YM15 catalogue still prints the bare impeller 128990-42200); it includes the cover O-ring. The very first 3YM30s (to May 2004) had impeller 128397-42200. The Johnson equivalent is confirmed only for the earlier 128990 pump (3YM30, 2YM15, 3YM20 up to serial E13045), not for the 128995 pump of the 3YM30AE and later 3YM20.
Engine oil filter119305-351703,9,4,8,7replaces 119305-35151replaces 119660-35150—3YM30 and 3YM30AE (also 2YM15, 3YM20). The AE catalogue prints 119305-35160, the same 68 × 65 mm filter.
Fuel filter (engine)104500-557103,4,10,11,8,7—Element, 3YM30 and 3YM30AE (also 2YM15, 3YM20). Fit a new bowl O-ring with it.
Fuel filter O-ring24341-0004403,4,12,8,7—Filter bowl O-ring; 3YM30 and 3YM30AE (also 2YM15, 3YM20).
Air filter128270-125403,4,13,8,7—Intake silencer element, 3YM30 and 3YM30AE (also 2YM15, 3YM20); Yanmar says clean it, not replace it, at the 250 h service.
Thermostat128990-498003,4,14,15,8,7—71 °C; 3YM30 and 3YM30AE (also 2YM15, 3YM20).
Alternator V-belt129612-422903,16,17,8,7,18replaces 119831-42290—A37.5 V-belt for the Hitachi 60/80 A alternator: 3YM30 up to serial E20847, 2YM15 up to E05887, 3YM20 up to E11905.
Alternator V-belt128990-775803,4,17—6PK ribbed belt, 3YM30 from serial E20848 (Valeo alternator) and all 3YM30AE. Not for the 2YM15/3YM20 — they take 128790-77580.
Alternator V-belt128790-775808,7,19—6PK ribbed belt for the 2YM15 from serial E05888 and the 3YM20 from E11906 (Valeo alternator). One digit away from the 3YM30’s 128990-77580 — compare carefully.
Seawater pump belt104511-787803,20,8,7—M19: 3YM30 from serial E01733 (up to E01732 the M20 belt 128990-77350), all 2YM15, and the 3YM20 from E00304 to E13045.
Seawater pump belt128990-773503,7,20replaces 25111-002000—M20: 3YM30 up to serial E01732; 3YM20 up to E00303 and again from E13046 with the 128995 pump (fitted as 25111-002000 up to E15077). Not used on the 2YM15.
Seawater pump belt128995-424504,21,22,7replaces 25111-002100—3YM30AE (M21). The 3YM20 with the same 128995 pump takes the M20 belt instead.
Raw water pump128990-425113,23,8,7,24replaces 128990-42510replaces 128990-42500—3YM30, all 2YM15 and the 3YM20 up to serial E13045; 128990-42510 replaced the original pump in 2009.
Raw water pump128995-425014,25,26,7replaces 128995-42500—3YM30AE and the 3YM20 from serial E13046; same impeller kit. Dealers also list the 2YM15, but its catalogue (2018) shows only the 128990 pump — check the pump on your engine.
Exhaust mixing elbow128890-135308,7,3,4,27replaces 128397-13530—Exhaust elbow on the cylinder head, the same on 3YM30, 3YM30AE, 2YM15 and 3YM20. It replaced 128397-13530 from serial E06685 (3YM30), E01478 (2YM15) and E10518 (3YM20). Mild steel, and the YM’s known rust spot.
Exhaust mixing elbow124070-135208,7,3,4—Water-injection mixing elbow of the standard L-type exhaust; it screws onto the elbow 128890-13530, on all four engines. 3YM20s built from October 2018 have a U-shaped mixing elbow 128890-13590 (assembly 128890-13600) instead; the optional high-riser exhaust uses other parts.
Exhaust elbow gasket128370-132018,7,3,4,28—Between cylinder head and exhaust elbow; the same on all four engines.
Glow plug119717-778018,7,3,4,29replaces 119717-77800—Same plug on all four engines: 2 on the 2YM15, 3 on the others. Replaces 119717-77800 (3YM20 catalogue: from March 2012); the 2YM15 catalogue still prints -77800.
Fuel injector119515-530018,7,3replaces 119515-53000—Complete injector, 2YM15 (2), 3YM20 and original 3YM30 (3 each); nozzle 119515-53010, holder 118200-53010, two seat gaskets 119600-11460 per cylinder. Not the 3YM30AE (next row).
Fuel injector119C10-530004—3YM30AE only, 3 per engine; nozzle 119C10-53010, holder 118200-53010. Catalogue only, one source.
Heat exchanger128990-444017,3,4,30replaces 128990-44400—Tube stack (element) of the heat exchanger: 3YM30, 3YM30AE and 3YM20; replaces -44400 (3YM20: from August 2005). Not the 2YM15 (next row).
Heat exchanger128790-444008—Shorter tube stack of the 2YM15 only. Catalogue only, one source.
Heat exchanger end-cap O-ring128990-441008,7,3,4,31—65.6 × 3.53 mm, four per engine, the same on all four engines; renew them when the tube stack comes out for cleaning.
Gasket set728990-926003—Complete engine gasket set, original 3YM30. Catalogue only, one source.
Gasket set728890-926007,32—3YM20 only.
Gasket set728790-926008—2YM15 only, with head gasket 119415-01330. Catalogue only, one source.

Numbers checked against the sources below on 12 October 2026. Always confirm against your serial number and exact type before ordering.

Service intervals

TaskInterval
Engine oil changeEvery 150 h or yearly, first time after 50 h33
Oil filterEvery 250 h or yearly, first time after 50 h33
Fuel filterEvery 250 h or yearly33
Fuel pre-filterDrain the fuel/water separator every 50 h or monthly33
Raw water impellerInspect every 250 h or yearly; replace every 1,000 h or 4 years even if undamaged34
Coolant changeYearly; every 2 years with long-life coolant33
Air filterClean every 250 h or yearly33
Exhaust elbow checkClean and inspect every 250 h or yearly; replace every 500 h or 2 years even if undamaged33
V-belt checkCheck tension after the first 50 h, then every 250 h or yearly; replace every 1,000 h or 4 years33
Gearbox oil changeKM2P-1: first after 50 h, then every 250 h or yearly (saildrive: see its own manual)33
Valve clearanceAfter the first 50 h, then every 1,000 h or 4 years (dealer)33
InjectorsSpray pattern and timing every 1,000 h or 4 years (dealer)33
Heat exchanger cleanClean the seawater passages every 1,000 h or 4 years (dealer)33

Hours or time, whichever comes first, from Yanmar’s YM operation manuals (2025 edition for the 2YM15, 3YM20 and 3YM30AE, 2009 edition for the 2YM15, 3YM20 and original 3YM30); the schedule is the same for all three engines.

Specifications

Cylinders3, in-line, four-stroke, indirect injection (2YM15: 2)34,33
Displacement3YM30: 1.115 l (76 × 82 mm); 3YM30AE: 1.266 l (80 × 84 mm); 3YM20: 0.854 l, 2YM15: 0.570 l (both 70 × 74 mm)34,33
Power3YM30: 21.3 kW (29 hp) at 3600 rpm, 3YM30AE: at 3200 rpm; 3YM20: 15.3 kW (21 hp), 2YM15: 10 kW (14 hp), both at 3600 rpm35,33,36,37
Engine oil capacity3YM30/3YM30AE: 2.8 l with KM2P-1 gearbox, 2.5 l with SD20/SD25 saildrive; 3YM20: 2.7 l / 2.4 l; 2YM15: 2.0 l / 1.8 l. Between the dipstick marks: 1.4–1.5 l (2YM15: 0.9–0.95 l)34,33
Engine oil gradeAPI CD, CF, CF-4, CI or CI-4; SAE 10W-30 or 15W-40 all year — not CG-4 or CH-4; the same for 2YM15 and 3YM2033,34
Coolant capacity3YM30/3YM30AE: 4.9 l, 3YM20: 4.1 l, 2YM15: 3.0 l in the engine, plus 0.8 l in the recovery tank33,34
CoolantLong-life coolant (LLC), 30–60 %; do not mix brands33
Thermostat opens at71 °C3,8,7
Injection pressure12.3–13.3 MPa (125–135 kgf/cm²), all three engines34,33
Injection timing3YM30: FID 16 ± 1° BTDC; 3YM20: FID 22 ± 1° BTDC; 2YM15: FID 21 ± 1° BTDC34,33
Alternator12 V; 3YM30: 60 A standard / 80 A optional, 3YM30AE: 125 A; 2YM15/3YM20: 60 A / 80 A (Hitachi) up to serial E05887 / E11905, then Valeo; current engines 125 A34,38,8,7,36,37
Starter motor12 V, 1.4 kW (2YM15, 3YM20, 3YM30)34,33
Dry weight3YM30: 123 kg bare, 133 kg with KM2P-1; 3YM30AE: 127 kg bare; 3YM20: 110 kg bare, 130 kg with KM2P-1; 2YM15: 103 kg bare, 113 kg with KM2P-135,38,33,36,37
GearboxKM2P-1 (2.21, 2.62 or 3.22:1) or SD20 saildrive (2.64:1); 3YM30AE: KM2P-1 or SD25. The 2YM15 and 3YM20 take the same gearboxes, current engines the SD2535,33,34
Gearbox oilKM2P-1: 0.3 l engine oil (API CD or better, SAE 20 or 30); SD20: 2.2 l (2.5 l long leg) SAE 90 or 80W-90 gear oil34
PredecessorYanmar 3GM3035

Good to know

  • Carry a spare impeller kit (128990-42570). Right after starting, check that cooling water comes out of the exhaust — too little seawater flow damages the impeller, and Yanmar wants it replaced every 1,000 h or 4 years even if it looks fine.34
  • Treat the exhaust mixing elbow as a wear part: Yanmar says to replace it every 500 h or 2 years even when no damage is visible.33
  • Read the serial number off the engine plate before ordering belts. On the 3YM30 the raw water pump belt changed at serial E01733 and the alternator — with its belt, now a 6PK ribbed belt — at E20848; the 2YM15 changed alternator at E05888 and the 3YM20 at E11906, and their 6PK belt is 128790-77580, not the 3YM30’s 128990-77580.17,8,7
  • 3YM30 and 3YM30AE look alike but differ inside. Filters, air element, thermostat and impeller kit are shared; the raw water pump and its belt are not — check which version you have before buying a pump.4
  • 3YM20 owners: from serial E13046 the raw water pump is the 128995 type of the 3YM30AE, with an M20 belt; earlier engines and all 2YM15 have the 128990 pump. Both take the same impeller kit 128990-42570, but pump and belt must match.7
  • The YM engines carry no sacrificial anode on the engine itself: none of the 2YM15, 3YM20, 3YM30 or 3YM30AE parts catalogues lists one. With a saildrive, keep an eye on the saildrive’s own anodes.8,7,3,4

Videos & how-tos

Links to YouTube, nothing embedded. The maker’s own channel comes first; the rest are channels we found clear and correct for this model.

Fitted in

Boats whose builder lists it as standard or optional equipment:

  • Excess 11 — Yanmar 3YM30 × 2 (All three builder lists (January 2020, December 2020, April 2024): two 29 hp diesels with saildrive, standard)
  • Lagoon 400 & 400 S2 — Yanmar 3YM30 × 2 (Named in Lagoon’s inventories of September 2015, March 2016 and October 2016: 29 hp each, with saildrive)
  • Leopard 40 — Yanmar 3YM30C × 2 (Mk II, from 2015: 29 hp each, with saildrives; Leopard gives 2 × 29 hp, the Moorings 4000 lists name the 3YM30C)
  • Jeanneau Sun Odyssey 349 — Yanmar 3YM20 (Standard in every list from November 2013 (model year 2014) to June 2022: 21 hp (15.3 kW) with shaft drive; no other engine is listed)

On the marketplace

Looking for a part for the Yanmar 3YM30? Post a wanted ad in the app — it is free, it sits on the live map, and boaters nearby who have the part aboard can answer.

Got spares you no longer need? List them in a minute. No commission, ever.

Get the app

Sources

  1. marineengineparts.com/johnson-pump-09-810b-1-impeller-kit/
  2. poseidonmarine.eu/products/impeller-135
  3. mecanique-plaisance-finistere.com/yanmar/pdfmoteur/3ym30.pdf
  4. mecanique-plaisance-finistere.com/yanmar/pdfmoteur/3ym30ae.pdf
  5. dieselpartsdirect.com/ym12899042570
  6. shop.marinedieselinc.com/products/128990-42570
  7. mecanique-plaisance-finistere.com/yanmar/pdfmoteur/3ym20.pdf
  8. mecanique-plaisance-finistere.com/yanmar/pdfmoteur/2ym15.pdf
  9. dieselpartsdirect.com/ym11930535170
  10. dieselpartsdirect.com/ym1045005571012
  11. shop.marinedieselinc.com/products/104500-55710
  12. dieselpartsdirect.com/ym24341000440
  13. dieselpartsdirect.com/ym12827012540
  14. dieselpartsdirect.com/ym12899049800
  15. shop.marinedieselinc.com/products/128990-49800
  16. dieselpartsdirect.com/ym11983142290
  17. dieselpartsdirect.com/ym12899077580
  18. dieselpartsdirect.com/ym12961242290
  19. dieselpartsdirect.com/ym12879077580
  20. dieselpartsdirect.com/ym12899077350
  21. dieselpartsdirect.com/ym25111002100
  22. dieselpartsdirect.com/ym12899542450
  23. shop.marinedieselinc.com/products/sea-water-pump-p-n-128990-42511
  24. dieselpartsdirect.com/ym12899042511
  25. dieselpartsdirect.com/ym12899542501
  26. shop.marinedieselinc.com/products/raw-water-pump-128995-42501
  27. dieselpartsdirect.com/ym12889013530
  28. dieselpartsdirect.com/ym12837013201
  29. dieselpartsdirect.com/ym11971777801
  30. dieselpartsdirect.com/ym12899044401
  31. dieselpartsdirect.com/ym12899044100
  32. dieselpartsdirect.com/ym72889092600
  33. yanmar.com/marine/wp-content/uploads/2020/03/0AYMM-M0002E_2025.02.pdf
  34. yanmar.com/media/global/com/product/marinepleasure/sailBoatPropulsion/operationmanual/YM_…
  35. yanmar.com/media/global/com/product/marinepleasure/sailBoatPropulsion/catalog/Yanmar-3YM3…
  36. yanmar.com/marine/product/engines/2ym15/
  37. yanmar.com/marine/product/engines/3ym20/
  38. yanmar.com/marine/product/engines/3ym30ae/

Yanmar is a trademark of its owner; boatparts.app is not affiliated with it. Part numbers are quoted for identification only. Spotted an error? Write to mail@boatparts.app.