Westerbeke marine diesels are marinized Mitsubishi blocks — buy the industrial part
Westerbeke's W-series and B-series diesels are mostly marinized Mitsubishi industrial engines (with two Perkins exceptions). Use the map to source internal parts as cheaper Mitsubishi spares.
Westerbeke = Mitsubishi (mostly)
Westerbeke's small and mid diesels — the W-series and the B-series (12B-Two, 30B-Three, 42B-Four and so on) — are marinized Mitsubishi industrial engines, mainly the L-series and K-series blocks. Internal service parts cross to Mitsubishi numbers through industrial channels. Two engines are the exception: they are Perkins, not Mitsubishi.
Westerbeke → base-engine map
| Westerbeke model | Base engine | Cyl |
|---|---|---|
| W10-Two | Mitsubishi K2AS | 2 |
| W13 | Mitsubishi K2C | 2 |
| W18 | Mitsubishi K3A | 3 |
| W21 | Mitsubishi K3D | 3 |
| W27 | Mitsubishi K4D | 4 |
| W33 | Mitsubishi K4F | 4 |
| 12B-Two / 20B-Two | Mitsubishi L2E | 2 |
| 30B-Three | Mitsubishi L3E | 3 |
| 35B-Three | Mitsubishi K3F | 3 |
| 38B-Four | Mitsubishi K4D | 4 |
| 42B-Four | Mitsubishi K4F | 4 |
The exceptions — the W40A and W52 are Perkins
- W40A → Perkins 4-107. A marinized Perkins 4-107 wet-liner block, not
Mitsubishi — internals cross to Perkins 4.107 numbers.
- W52 → Perkins 4-135. A marinized Perkins 4-135 block (itself a Toyo
Kogyo / Mazda R2 casting). Internals cross to Perkins 4.135 numbers — and, two hops out, to the Mazda R2 (as used in the Mazda B2200 and Ford Ranger).
If you have a W40A or W52, look these up as Perkins engines, not Mitsubishi.
The B-series is only sometimes Mitsubishi — don't assume a B-series engine is Kubota or anything else without checking the base-engine line on its page. Mitsubishi K/L codes are widely documented but a few are inferred from displacement; confirm against a Mitsubishi dealer before ordering. See our Methodology.
Find your Westerbeke's parts
Open your model above and use its "Industrial / tractor part equivalents" view. For consumables, see the impeller, oil filter and fuel filter charts.
This is an independent reference guide. Part numbers are compiled from public and third-party sources and may contain errors — always verify against an official source before ordering. See our Methodology. Browse all guides.