Beta Marine · Inboard diesel

Beta Marine Beta 25 & Beta 30

Beta Marine marinises Kubota industrial diesels in Gloucestershire, England. The Beta 25 is a three-cylinder 898 cc engine on the Kubota D902 block (Beta code BD902) with 25 hp at 3,600 rpm; the Beta 30 is its 1,123 cc sibling on the Kubota D1105 (BD1105) with 30 hp. Both are indirect-injection engines with a mechanical in-line injection pump, a gear-driven camshaft (no timing belt), a heat exchanger with header tank and a wet exhaust, and both are a common repower in sailing yachts of 27–36 ft. Beta builds to order, so alternator, belt, gearbox and oil-filter position depend on the build date and the works order; Beta’s parts list for the Beta 30 also covers the Beta 28, and several Beta 25 items are shared with the Beta 16.

Manuals & documents

The links go straight to Beta Marine. 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)207-09041-KIT1,2,3,4,5replaces 207-05355—Beta 25 and Beta 30 with Beta Marine’s own gear-driven pump (from June 2013; side-mounted Beta 28/30 pump from January 2013) or with the Johnson pump (Beta 10–25: July 2006 to June 2013; Beta 28/30: July 2006 to January 2014). Includes the end-cover O-ring; replaces the Johnson kit 207-05355.
Raw water pump impeller207-796301,2,6Jabsco 18653-00016Engines with the original Jabsco gear-driven pump (parts lists: to July 2006; Beta Marine USA says Jabsco pumps on Beta 28–38 up to September 2009). Comes with a gasket for the round 6-screw cover or an O-ring for the triangular 3-screw cover.
Pump cover O-ring207-092791,2—End-cover O-ring of the Beta Marine pump (from June 2013), both engines. Johnson pump: O-ring 209-07291. Jabsco pump: gasket 207-62600 (round cover) or O-ring 207-04206 (triangular cover). Pump-to-engine O-ring 209-08266 for Beta and Johnson pumps.
Raw water pump207-089221,2—Beta Marine gear-driven pump from June 2013, both engines. Side-mounted Beta 28/30 version from January 2013: 207-61460/01. Johnson pump (July 2006 to 2013/14): 207-29145. Jabsco pump (to July 2006): 207-61500.
Pump seal kit207-092281,2—Seal kit for the Beta Marine pump (from June 2013), both engines; wear kit 207-09909 (with impeller backing plate), shaft kit 207-09229, lip seals 207-09351 (28 mm, 2 off) and 205-10361 (24 mm). Johnson pump: service kit 207-07714, lip seal 207-06494. Jabsco pump: 207-61470 (round cover) or AK/MINI/HE/SWPI/001 (triangular cover).
Engine oil filter211-637601,3,7,8—Beta 25 (also Beta 10/14/16/20) with the engine-mounted filter, about 70 × 85 mm. Not for the Beta 30.
Engine oil filter211-603902,9,10—Beta 30 (also Beta 28/35/38/45T) with the engine-mounted filter, heat-exchanger and keel-cooled. Not for the Beta 25.
Engine oil filter211-70510/021,2,3,11,12—Both engines when built with the optional remote bulkhead-mounted filter head; the same element as on the Beta 43–115T.
Fuel filter (engine)211-602101,2,3,13,14—Beta 25 and Beta 30 heat-exchanger engines, for the round housing with bleed bolt and the square housing with priming button. Keel-cooled Beta 30: 211-02817.
Fuel lift pump600-10432 · 600-678301,2—600-10432 for the Beta 25 (and Beta 16), 600-67830 for the Beta 30 (and Beta 28); gasket 600-00065 for both.
Air filter211-081321,2,3—Plastic filter housing: Beta 25 from March 2011, Beta 28/30 from January 2012 (Beta 30 with mechanical gearbox from March 2011). Earlier two-clamp type to March 2011: 211-62950. Beta 30 with hydraulic gearbox: 211-08133 (2011) or 211-61831 (to December 2010).
Alternator V-belt212-050741,3,15,16—Beta 25: 4PK polyvee belt, 913 mm, for the standard 40 A and the optional 75 A alternator, all years. 120 A or 70 A insulated-return alternator: 6PK belt 214-04124 (2011 to September 2023) or 214-01469 (from September 2023). Optional 40 A V-belt alternator: 214-00126 (from 2011), 600-63080 (before).
Alternator V-belt214-046182,17,18,19—Beta 30 (and Beta 28): 6PK polyvee belt, 1038 mm, for the standard 70 A and the optional 120 A / 70 A insulated-return alternators on heat-exchanger engines from October 2009; before October 2009: 214-00493. V-belt alternators (70 A, earlier 65 A): cogged belt 214-63090/Q. Keel-cooled with 40 A V-belt alternator: 600-94280/01. Second 100 A domestic alternator: 214-02614.
Thermostat600-724501,2—Beta 25 (and Beta 16) and Beta 28/30; the Beta 10/14/20 use 600-59290.
Thermostat gasket600-804901,2—Beta 25 (and Beta 16) and Beta 28/30; Beta 10/14/20: 600-00553.
Anode (engine)209-618401,2,3,20—Pencil anode in the heat-exchanger end cap, both engines (all Beta heat-exchanger engines). Magnesium 209-23104 or aluminium 209-23365 for fresh or brackish water.
Pressure cap209-801301,2—Header-tank cap, Beta 25 and Beta 28/30 heat-exchanger engines (13 psi system).
Heat exchanger end-cap O-ring212-072731,2,3—3-bolt end caps, two per engine, both engines; the single-bolt end cap takes 209-80110. Renew when the tube stack is cleaned.
Exhaust mixing elbow202-024581,2—Standard 2 in (50 mm) aluminium water-injection bend, Beta 25 and Beta 28/30 from October 2002; angled and cross-over bends are listed separately.
Exhaust elbow gasket212-090701,2—Orange gasket type, from May 2011, both engines.

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

Service intervals

TaskInterval
Oil level checkDaily or every 8 h: engine and gearbox oil, coolant, battery fluid, belt tension and alternator bolts, raw-water strainer, stern gland3
Fuel pre-filterDrain the water from the fuel/water separator daily or every 8 h3
Engine oil changeAfter the first 50 h, then yearly or every 250 h (every 150 h with a shallow sump)3
Oil filterWith every oil change: after the first 50 h, then yearly or every 250 h (150 h with a shallow sump)3
Gearbox oil changeAfter the first 25 h, then as the gearbox manual says3
Fuel filterEvery 250 h or yearly3
Raw water impellerCheck yearly or every 250 h and replace if worn; remove it when the boat is laid up for more than 6 months3
AnodeCheck after the first 50 h, then yearly or every 250 h and replace as needed; more often where erosion is heavy3
Heat exchanger cleanRemove and clean the tube stack yearly or every 250 h, with new end-cap O-rings (212-07273 for 3-bolt caps, two per engine)3,1,2
Coolant changeCheck the condition yearly or every 250 h; renew every 2 years or 500 h3
V-belt checkCheck the tension daily or every 8 h3
Air filterCheck and clean yearly or every 250 h; replace every 500 h3
Valve clearanceEvery 1500 h3
InjectorsCheck the nozzle opening pressure every 1500 h3

Hours or time, whichever comes first, from Beta Marine’s operator’s maintenance manual for the Beta 10 to Beta 115T heat-exchanger engines (revision 46). Beta Marine USA’s aftercare page shows a few items differently; the manual’s table was used.

Specifications

TypeBeta 25: Kubota D902 (Beta code BD902) · Beta 30: Kubota D1105 (Beta code BD1105); marinised industrial diesel3
Cylinders3 in line (both)3
AspirationNaturally aspirated3
DisplacementBeta 25: 898 cc · Beta 30: 1123 cc3
Bore × strokeBeta 25: 72.0 × 73.6 mm · Beta 30: 78.0 × 78.4 mm3
Compression ratio24.0:1 (both)3
PowerBeta 25: 25 hp (18.5 kW) at 3600 rpm · Beta 30: 30 hp (22.1 kW) at 3600 rpm; maximum rating per EU directive 2013/53/EU3
Maximum torqueBeta 25: 56.1 Nm at 2400 rpm · Beta 30: 65.2 Nm at 2600 rpm3
Rated speed3600 rpm (both)21,22
InjectionIndirect (Kubota E-TVCS three-vortex chamber); mechanical in-line injection pump, mechanical lift pump, all-speed mechanical governor21
StartingGlow plugs for cold starting21
Injection pressure140 kgf/cm² (1991 psi), both engines3
Injection timingBeta 25: 21° BTDC · Beta 30: 17° BTDC3
Valve clearance (cold)0.165 mm (0.0064 in), both engines3
Firing order1-2-33
CoolingHeat exchanger with header tank, fresh-water-cooled exhaust manifold, gear-driven raw-water pump, wet exhaust with water-injection bend23
Engine oil capacityBeta 25: 4.5 l standard sump, 3.8 l shallow sump · Beta 30: 5.1 l standard sump, 4.0 l shallow sump3
Engine oil gradeAPI CF or better; SAE 15W-40 above 0 °C (10W-30 from −30 to 0 °C); mineral or semi-synthetic with at most 30 % synthetic content, no fully synthetic oil, no additives3
Coolant capacityBeta 25: 3.25 l · Beta 30: 5.5 l (engine circuit only, without calorifier and hoses)3
CoolantMono-ethylene-glycol long-life antifreeze, 30–50 % in fresh water (also in the tropics), never more than 50 %3
Alternator12 V; Beta 25: 40 A standard, 75 A or 120 A optional · Beta 30: 70 A standard, 120 A optional; polyvee belt drive21,22
GearboxTMC40 mechanical (Technodrive/Twin Disc) standard; TMC60, TMC60A down-angle, PRM60/90/125/150, ZF15MIV V-drive and others optional; also sold bobtail without gearbox21,22
Dry weightBeta 25: approx. 113 kg · Beta 30: approx. 139 kg, with standard gearbox3
BatteryStarter battery at least 70 Ah / 450 CCA (both)3
PropellerTypical guidance for a 3-blade right-hand propeller with 2:1 reduction: Beta 25 14 × 8 in · Beta 30 15 × 9 in24,23

Good to know

  • Identify the raw-water pump before buying an impeller: the Jabsco pump (to 2006) takes impeller 207-79630, while the Johnson pump (2006 to 2013/14) and Beta’s own gear-driven pump (from June 2013) both take kit 207-09041-KIT.1
  • Two oil-filter sizes: the Beta 25 takes the small 211-63760, the Beta 30 the larger 211-60390 — unless the engine has a remote bulkhead filter, which takes 211-70510/02 on both.7
  • Beta builds every engine to order, so quote the works-order ‘K’ number and the engine serial when ordering belts, alternator parts or filters; alternator rating and build date decide the belt.25
  • No fully synthetic oil: Beta specifies API CF 15W-40 mineral or semi-synthetic (max. 30 % synthetic), and 30–50 % mono-ethylene-glycol antifreeze even in the tropics — the warranty depends on it.3
  • When charging batteries or running an inverter out of gear, keep the engine at 1,200 rpm or more; Beta warns that prolonged charging below that can cause damage.3
  • Change the oil at the end of the season rather than in spring, fill the raw-water side with antifreeze where it can freeze, and pull the impeller if the boat is laid up for more than six months.3

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:

  • Contessa 32 — Beta Marine Beta 25 (New-build specification 2023: three cylinders, 25 hp, fresh-water cooled, two-blade fixed propeller on a conventional shaft)

On the marketplace

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Sources

  1. betamarine.co.uk/resources/Illustrated_Parts_Lists/B10-B25-IPL/
  2. betamarine.co.uk/resources/Illustrated_Parts_Lists/B28-B30-IPL/
  3. betamarine.co.uk/resources/Operators_Manuals/10-115T-HE-OM/
  4. parts.betamarineusa.com/product/impeller-kit-3/
  5. parts.betamarineusa.com/product/impeller-kit-5/
  6. parts.betamarineusa.com/product/jabsco-impeller-18653-0001/
  7. parts.betamarineusa.com/product/oil-filter/
  8. sheridanmarine.com/product/beta-marine-211-63760-oil-filter
  9. parts.betamarineusa.com/product/oil-filter-2/
  10. sheridanmarine.com/product/beta-marine-211-60390-oil-filter
  11. parts.betamarineusa.com/product/oil-filter-3/
  12. sheridanmarine.com/product/beta-marine-211-7051002-oil-filter
  13. parts.betamarineusa.com/product/fuel-filter/
  14. sheridanmarine.com/product/beta-marine-211-60210-fuel-filter
  15. parts.betamarineusa.com/product/polyvee-drive-belt/
  16. parts.betamarineusa.com/product/v-drive-belt-5/
  17. parts.betamarineusa.com/product/polyvee-drive-belt-3/
  18. parts.betamarineusa.com/product/polyvee-drive-belt-2/
  19. parts.betamarineusa.com/product/cogged-v-drive-belt-2/
  20. parts.betamarineusa.com/product/209-61840-zinc-anode/
  21. betamarine.co.uk/resources/Data_Sheets/Seagoing/B25-DS/
  22. betamarine.co.uk/resources/Data_Sheets/Seagoing/B30-DS/
  23. betamarine.co.uk/portfolio/beta-30/
  24. betamarine.co.uk/portfolio/beta-25/
  25. betamarine.co.uk/spares-service-parts/

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