Sometimes it seems that Yanmar’s small marine diesel engines have crazy names. From the 3JH(B)E to the 4JH4E it’s sometimes hard to know what you’re dealing with. Don’t worry though – if you know what to look for, you can decode all the numbers and letters. Yanmar Engine Model Codes can tell you everything yopu need to know and you’ll soon be able to tell your 4JH3-T(B)E from your 4JH2-DT(B)E like a pro.
What do the Yanmar Engine Model Codes mean?
The nomenclature of the engine name codes on Yanmar small marine diesel engines tell us all the information we need to know about the engine. They explain;
- The number of cylinders,
- The engine family,
- Some extra miscillaneous information relating to that family,
- Specification upgrades such as the addition of a turbo,
- Possibly some information about the stern gear.
Where to find the code on a Yanmar Marine Diesel?
The plate on your engine should have all the necessary information. The transmission will have its own seperate plate with details about drive ratios etc.
If an engine does not have the Y in the beginning of the code, then it has a vertically mounted cylinder block. Y engines, such as the YSE12, had a horizontally mounted cylinder.
The numbers 1, 3, 4, and 6 indicate the number of cylinders. So for example, 3GM is a 3 cylinder engine with a GM type block. A 2GM is a 2 cylinder engine with a GM type block, and so on.
Note also that older engine families didn’t strictly follow the rules. The 1GMs, 2GMs and 3HMs, for example, existed prior to upgrading the cylinders to become 1GM10, 2GM20 and 3HM35 respectively.
| Model Code | Years of production | Variants |
|---|---|---|
| Y Series Engines | 1967 - 1980 | YSB12 YSB8 YSE12 YSE8 YSM12 YSM8 |
| S Series | 1976 - 1980 | SB12 SB8 SVE12 SVE8 |
| QM Series | 1977 - 1980 | 2QM (Japan only) 2QM15 2QM20 (22 HP) 2QM20-F 2QM20-H 3QM (Japan only) 3QM30 (33 HP) 3QM30-F 3QM30-H |
| GM/HM Series | 1980 - 1983 | 1GM (7.5 HP) 2GM (15 HP) 2GMF (15 HP) 3GM (22.5 HP) 3GMF (22.5HP) 3GMD (22.5 HP) 3HM (30 HP) 3HMF (30 HP) |
| GM/HM Upgraded Series | 1983 - present* * not all models | 1GM10 (9 HP) 2GM20 (18 HP) 2GM20-YEU (18 HP) 2GM20F (18 HP) 2GM20FYEU (18 HP) 3GM30 (27 HP) 3GM30-YEU (27 HP) 3GM30F (27 HP) 3GM30F-YEU (27 HP) 3HM35 (34 HP) 3HM35F (34 HP) |
| YM Series | 2004 - present | 2YM15 (14 HP) 3YM20 (22 HP) 3YM30 (30 HP) |
| JH Series | 1983 - 1989 | 4JH-DTE (77 HP) 4JH-E (44 HP) 4JH-TE (55 HP) 4JH-THE (66 HP) |
| JH2 Series | 1989 - 1999 | 3JH(B)E (38 HP) 3JH2-T(B)E (47 HP) 4JH2-(B)E (51 HP) 4JH2-DT(B)E (88 HP) 4JH2-HT(B)E (76 HP) 4JH2-T(B)E (63 HP) 4JH2-UT(B)E (100 HP) |
| JH3 Series | 1999 - 2006 | 3JH3 (40 HP) 4JH3-DTBE (125 HP) 4JH3-HTBE (100 HP) 4JH3-T(B)E (75 HP) 4JH3E (56 HP) |
| JH4 Series | 2004 - present | 3JH4E (40 HP) 4JH4E (55 HP) |