Bukh · Inboard diesel

Bukh DV20

The Bukh DV20 is a two-cylinder, 0.964-litre marine diesel with indirect injection, rated 20 hp (DIN) at 3000 rpm and built in Aabenraa, Denmark. It came as the DV20 M with hand start, the DV20 ME with electric start and the DV20 SME with Bukh’s own saildrive, and it was a common auxiliary in Scandinavian and British sailing yachts of the 1970s and 1980s. As standard it is cooled directly by raw water through a thermostat; fresh-water cooling with a heat exchanger was an option. The single-cylinder DV10 is its sibling and shares the pumps, filters, belts, thermostats and block anode; the later DV24 and the larger Bukh engines are not covered here. Bukh dealers still supply many DV20 wear parts, some under newer numbers (head gasket, pump repair kit, thermostat insert), so quote the engine number with every order.

Manuals & documents
Wear parts & part numbers
Service intervals
Specifications
Good to know
Videos & how-tos
Fitted in
On the marketplace

Manuals & documents

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

Instruction book DV10 and DV20 (M, ME, SME), 1981 (Danish) Operation manual sw10696.smartweb-static.com · PDF · DA
Spare parts list DV10/DV20, publ. no. 009W1207 (Danish, English, German, Spanish, French) Parts catalogue sw10696.smartweb-static.com · PDF · DA · EN · DE · ES · FR
Bukh download page for operator manuals (all DV engines) Manual portal bukh.dk · EN
Bukh download page for spare parts lists (all DV engines) Manual portal bukh.dk · EN
Bukh Bremen: online shop for Bukh spare parts, searchable by Bukh part number Parts shop bukh-bremen.de · DE

Wear parts & part numbers

Part	OEM number	Also fits	Note
Raw water pump impeller	`610G0102`^2,1	Johnson Pump `09-808B-1`¹	Impeller with bush for raw water pump 610G0100: DV20 from engine no. 97549 (DV10 from no. 203812). Cover gasket 610G0103, shaft seal rings 561B0127 (2) and O-ring 560F1011 belong to the same pump.
Raw water pump impeller	`610G0092`^2,3	Johnson Pump `09-806B-1`³	Impeller with bush for the earlier pump 610G0090: DV20 up to engine no. 97548. Cover gasket 610G0073, seal rings 561B0129 (2), O-ring 560F1012.
Raw water pump impeller	`610G0121`^2,4	—	Impeller for raw water pump 610G0120 on DV20 engines with fresh-water cooling (heat exchanger). Gasket 610G0122, seal rings 561B0129 (2). Bukh Bremen lists the same impeller for DV24 to DV48 and for older DV8, DV10L, DV10 and DV20.
Pump cover gasket	`610G0103`²	—	Cover gasket for pump 610G0100 (DV20 from no. 97549). Earlier pump 610G0090: 610G0073; pump 610G0120 on fresh-water-cooled engines: 610G0122.
Water pump repair kit	`030D1807`^2,5replaces 610G0108	—	Bukh repair kit for pump 610G0100 (DV20 from no. 97549). The parts list shows 610G0108; Bukh Bremen sells it today as 030D1807 (“repair kit for Johnson pump, ex 610G0108”). Earlier pump 610G0090 on the DV20: 610G0097; pump 610G0120 on fresh-water-cooled engines: 610G0127.
Raw water pump	`610G0100`^2,7,6	Johnson Pump `F35B-9`⁶	Complete pump for raw-water-cooled DV20 from engine no. 97549; earlier engines have pump 610G0090. It seals to the engine with O-ring 560B1032. The Johnson F35B-9 is sold as a replacement for 610G0100 on DV10/18/20/24 ME/SME with direct cooling; order O-ring 560B1032 and two clamps 01-43238 with it.
Engine oil filter	`610J0050`^2,8,9	—	Spin-on paper filter, the same on DV10 and DV20; it cannot be cleaned. The 1981 book names OK-SF 4 or MANN V 712/4 as the filter (printed so; ask a dealer for today’s MANN number).
Fuel filter (engine)	`610D0053`^2,8,10,11	—	Paper element of the bowl-type filter 610D0050 between lift pump and injection pump; the same on DV10 and DV20. Fit a new bowl gasket (530P1020) with each element. The 1981 instruction book names the filter as Bosch 0 450 015 014. Late DV20 ME from no. 104271 have the spin-on cartridge 610D0201 instead.
Fuel filter (engine)	`610D0201`¹²	—	Spin-on fuel filter cartridge. Bukh Bremen lists it for the DV20 ME from engine no. 104271 (DV10 ME from no. 207292) and for the DV18, DV24, DV29, DV32, DV36 and DV48; earlier DV20s have the bowl filter with element 610D0053. It is not in the parts list behind this page, so check which filter your engine carries.
Fuel lift pump	`610C0080`^2,8,13	—	S.E.V. Marchal diaphragm lift pump with hand-priming lever; repair kit 610C0081, mounting gasket 000D2375. The gauze pre-filter sits under its cover. Bukh Bremen also sells a lift pump conversion kit for the DV10/20, 030D0607, with reference to Bukh service information SI0003.
Fuel injector	`610B9050`^2,8,14,15	—	Complete fuel valve (nozzle holder), two per engine, the same on DV10 and DV20; it screws into the pre-chamber at 6–8 kpm and opens at 150 kp/cm², set with shims 530P1030 to 530P1037. The nozzle alone is 610B9052, the pressure spring 610B9054; gasket 530P1010 sits under each fuel valve.
Injector sealing washer	`530P1010`^2,16	—	Gasket under each fuel valve, two per engine (Bukh Bremen calls it a heat-shield and sealing plate for the DV10/20 ME); also in the valve-grinding set 032D4202. The gasket under each pre-chamber top is 000D8497.
Alternator V-belt	`542A0213`^2,17	—	V-belt S42 for electric-start engines with alternator 612H0100: DV20 from engine no. 93638 (DV10 from no. 89157). Earlier DV20: V-belt 23S 542A0257 with the alternator, or Rofan 6190 542A0620 with the Dynastart.
Drive belt	`542A0263`²	—	Second V-belt on fresh-water-cooled engines; it drives the circulation pump.
Coolant pump	`008E3560`^2,18	—	Belt-driven circulation pump of the fresh-water (heat exchanger) system, driven by V-belt 542A0263. Bukh Bremen sells circulation pump 030D4727 (formerly 008E4727) for DV10/20/24/29/32 only as a complete unit, with no spare parts; compare its 32 mm water connections with yours before ordering.
Thermostat	`030D1802`^2,8,19	—	Complete thermostat for direct raw-water cooling, DV20 from engine no. 97549 (DV10 from no. 203812); Bukh Bremen sells it as a conversion kit for older DV10/20 engines. The insert alone is listed below. Earlier engines: complete unit 030D1801 with element 530Q9941.
Thermostat	`008E6577`^2,20replaces 530Q9947	—	60 °C insert for the raw-water thermostat housing of the DV20 from no. 97549; the parts list shows 530Q9947, which Bukh Bremen has replaced with 008E6577 (for DV10, DV20 and DV24, gasket 000E2584).
Thermostat	`000E3302`^2,21	—	75 °C thermostat of the fresh-water (heat exchanger) system; complete unit 030D1805. For fresh-water-cooled DV10 to DV32, Bukh Bremen today sells the 75 °C thermostat 008E8530 (formerly 008E6588); ask whether it fits your housing.
Thermostat gasket	`000E2584`^2,22,23	—	Thermostat gasket for the later raw-water housing (from DV20 no. 97549) and the fresh-water system; the housing gasket is 000E1851.
Anode (engine)	`008E0451`^2,8,24,25	—	Zinc rod complete with screw plug, screwed into the cooling space at the back of the crankcase; the same on DV10 and DV20. The zinc rod alone is 000E0450. Bukh also listed hull anodes 020D1601 (0.2 kg) and 020D1602 (1.0 kg).
Anode plug gasket	`522C3025`²	—	Copper sealing ring A 17 × 21 DIN 7603 under the block anode.
Saildrive anode	`000E5829`^26,8	—	Zinc anode of Bukh’s saildrive (DV20 SME); Bukh Bremen lists it for the DV10 SME to DV48 SME, fixing screw 502U2311. Check it once a year and renew it when badly corroded; paint the leg only with copper-free antifouling.
Cylinder head gasket	`000E7766`^2,8,27replaces 000D9687	—	DV20 only (DV10: 000D8496). The parts list shows 000D9687; Bukh Bremen sells the DV20 head gasket today as 000E7766. The head sits on seven studs 000E3467 and two studs with guide ring 008E3466, with nine M12 nuts 510A1210; tighten them to 9.5–10.5 kpm.
Valve cover gasket	`000E1540`^2,28	—	Gasket of the cylinder head cover, DV20 from engine no. 92447; earlier DV20s (up to no. 92446) have cover 000D9889 with gasket 000D9665.
Oil sump gasket	`000D9734`^2,29	—	Gasket of the base cover under the crankcase, DV20 (DV10: 000D9311); Bukh Bremen lists it for DV20, DV24 and DV29.
Exhaust manifold gasket	`000D9881`^2,30	—	Gasket of the water-cooled exhaust manifold 000D9760, two per DV20; Bukh Bremen lists it for DV20, DV24 and DV29. Both are in the gasket sets 032D4201 and 032D4202.
Front crankshaft seal	`561B0595`^2,31replaces 561B0600	—	Oil seal in the front end cover. The parts list shows 561B0600 (60 × 80 × 8 mm) for DV10 and DV20; Bukh Bremen sells 561B0595 (59.5 × 80 × 10 mm) in its place for DV10 to DV32.
Gasket set	`032D4201`^2,32	—	Complete engine gasket set for the DV20 (DV10: 031D4201).
Gasket set	`032D4202`^2,33	—	Valve-grinding (top-end) gasket set for the DV20 (DV10: 031D4202), with the head gasket and the gaskets for fuel valves, pre-chambers, exhaust manifold and thermostat housing.
Air filter	`611A0020`^2,8	—	Wire-mesh air filter with intake silencer, the same on DV10 and DV20; it is washed rather than replaced (see intervals).
Stop solenoid	`008E2922`^2,8,34replaces 032D0702replaces 612E0060	—	Stop solenoid of electric-start engines, DV20 from engine no. 93638: the parts list shows the complete unit 032D0702 with solenoid 612E0060, and Bukh Bremen supplies 008E2922 in their place for DV8 to DV32. Do not leave the key in the stop position, the solenoid draws a lot of current.
Propeller shaft seal	`561B0250`^2,8,35	—	Seal ring in the stuffing box of Bukh’s flexible stern tube, two per stuffing box in the parts list (Bukh Bremen lists it for the 25 mm shaft). Bukh says to renew the stuffing-box seal rings and the rubber hose every three years.
Onboard spares kit	`032D4210`⁸	—	Bukh’s spares set for the raw-water-cooled DV20: fuel filter element, oil filter, injection pipe, raw water pump impeller, alternator V-belt and original Bukh red paint. The same set for fresh-water-cooled DV20 engines is 032D4211.
Cold-start aid (Thermostart)	`022D2204`⁸	—	Thermostart inlet-air heater, an option Bukh recommends for starting below +7 °C; switch it on with the key for 15–20 seconds before starting. The DV10 uses 021D2204.

Numbers checked against the sources below on 23 October 2026. Always confirm against your serial number and exact type before ordering.

Service intervals

Task	Interval
First service	First 25 h at no more than 80 % of full power (2700 rpm) and no heavy towing; then change engine and gear oil and check the V-belt tension⁸
Engine oil change	Every 150 h or yearly, first time after 25 h⁸
Oil filter	Every 150 h or yearly⁸
Oil level check	Engine and gear oil every 14 days or 25 h, and at the annual launch⁸
Gear oil change	ZF gear and saildrive: first after 25 h, then every 150 h or yearly⁸
Fuel filter	Element every 300 h and at the annual launch, or at once if water got into the filter; bleed the system afterwards⁸
Fuel pre-filter	Clean the gauze under the lift pump cover in clean diesel every 150 h or yearly⁸
Air filter	Clean the wire-mesh filter in petrol and blow it out with compressed air every 300 h⁸
V-belt check	Check and adjust after the first 25 h, then every 150 h; it should press in 15–20 mm on the longest free run⁸
Raw water impeller	Renew at each annual launch, or take it out over winter and store it separately⁸
Anode	Check every 25 h and at launch; take it out 2–3 times a year and replace it when badly eaten away⁸
Shaft seal (stuffing box)	Top up the inner stern tube gland with outboard gear oil every 14 days or 25 h (never with a grease gun); on Bukh’s flexible stern tube renew the stuffing-box seal rings and the rubber hose every three years⁸
Injectors	Check every 600 h, the electric starter at the same interval⁸
Clean oil sump & suction strainer	Every 600 h⁸
Battery	Check the electrolyte every 14 days or 25 h and at the annual launch: 5–6 mm above the plates, top up with distilled water⁸
Corrosion protection	Hull zinc (Bukh recommends one BERA 2B): check it every time the boat is ashore, at least twice a year⁸
Saildrive anode	Saildrive (SME): check once a year or as needed, renew when badly corroded⁸
Saildrive diaphragm	Test the water alarm between the two diaphragms twice a year: bridge pins 1 and 2 on the plastic box beside the multi-plugs; buzzer and lamp must come on⁸

From the maintenance table and text of Bukh’s 1981 instruction book for the DV10 and DV20 (in Danish). Hours or time, whichever comes first; “yearly” there means at the annual launch.

Specifications

Versions	DV20 M (hand start), DV20 ME (electric start), DV20 SME (with Bukh saildrive); the DV10 M/ME/SME is the single-cylinder sibling⁸
Cylinders	2, in-line, four-stroke⁸
Combustion	Indirect injection, Bukh two-stage combustion with pre-chamber⁸
Displacement	0.964 l⁸
Bore × stroke	85 × 85 mm⁸
Compression ratio	21.5:1⁸
Compression pressure	48 kp/cm² (about 47 bar), stated for 2000–3000 rpm⁸
Power	20 hp DIN at 3000 rpm (16.8 hp at 2400 rpm, 12.8 hp at 2000 rpm)⁸
Maximum torque	5.0 kpm DIN (about 49 Nm) at 2700 rpm⁸
Idle speed	900–1200 rpm⁸
Direction of rotation	Clockwise, seen from the front⁸
Max. installation angle	12° aft, 25° sideways (DV10: 15° aft)⁸
Cooling	Standard: direct raw-water cooling with thermostat, 50–75 °C; rubber-impeller pump of Johnson 10-35118-1 type, 11 l/min. Option: fresh-water cooling with heat exchanger (kit 022D1210), 70–90 °C, 75 °C thermostat and a belt-driven circulation pump⁸
Coolant capacity	3.25 l with direct cooling; 4.80 l in total with heat exchanger⁸
Engine oil capacity	2.75 l including filter (DV10: 1.75 l)⁸
Engine oil grade	API CC, or CD for hard use or fuel with more than 1 % sulphur; SAE 10 or 5W-20 below +5 °C, SAE 20 from +5 to +25 °C, SAE 30 above +25 °C⁸
Oil pressure	2–4 kp/cm² with the engine warm, minimum 1 kp/cm² (1 kp/cm² ≈ 1 bar)⁸
Gearbox	ZF reverse-reduction gear (M and ME; the instruction book gives 2.5:1 ahead and 2.36:1 astern for the DV20 M) or Bukh saildrive (SME), 2.25:1 ahead and astern⁸
Gearbox oil	ZF gear: 1.1 l, API CC or CD, SAE 20W-20 or SAE 30, oil temperature max. 120 °C⁸
Drive oil	Bukh saildrive: 3.3 l, same grade as the ZF gear (API CC or CD)⁸
Fuel	Diesel to BS 2869 Class A; S.E.V. Marchal lift pump, 0.325–0.562 kp/cm²⁸
Injection pressure	150 kp/cm² (about 147 bar)⁸
Injection timing	14.7° before TDC (50 mm on the rim of the 391 mm flywheel)⁸
Valve clearance (cold)	Inlet 0.25 mm, exhaust 0.30 mm (cold engine)⁸
Tightening torques	Cylinder head nuts 9.5–10.5 kpm (about 93–103 Nm; DV10: 15–17 kpm), connecting-rod bolts 4.7–5.3 kpm, injector holder in pre-chamber 6–8 kpm, pre-chamber 24–25 kpm, flywheel 8–8.5 kpm, rocker pillar 4–4.5 kpm, flexible coupling engine–gear 6–6.5 kpm (1 kpm ≈ 9.8 Nm)⁸
Battery	12 V, max. 88 Ah⁸
Starter motor	Paris-Rhône D9E 51 or Bosch 0 001 314 031, 2 hp; stop solenoid Bosch 0 330 101 024⁸
Alternator	Paris-Rhône A13N1M, 700 W; electric-start engines from DV20 no. 93638 have alternator 612H0100 with V-belt S42^8,2
Dry weight	approx. 200 kg (M), 210 kg (ME), 220 kg (SME), net without accessories⁸

Good to know

Read the engine number before you order: it is stamped on the front of the crankcase, port side, and Bukh asks for type and number with every order. On the DV20 the raw water pump (610G0090, then 610G0100) and the thermostat changed at no. 97549, the alternator and its belt at no. 93638. According to Bukh Bremen, late DV20 ME from no. 104271 take the spin-on fuel filter 610D0201 instead of the bowl-filter element.^2,8,12
The impeller does not simply pull out: it is pinned to the pump shaft. Drain the water, loosen the pipes, undo the two flange screws and take the pump off, remove the front cover, push shaft and impeller out from behind and drive out the through-pin to change the impeller. Reassemble in reverse order, and keep a spare impeller and shaft seal rings on board.⁸
The standard thermostat is a bellows type that fails open: if the engine never gets above about 50 °C, suspect the thermostat rather than the cooling. The insert comes out after undoing the four nuts on the housing cover. Overheating lights the blue lamp and sounds the buzzer on the panel.⁸
Bukh recommended the fresh-water cooling kit with heat exchanger (022D1210) for engines running more than 500 h a year: it raises the working temperature to 70–90 °C. Protect that circuit against frost with 25 % glycol, filled at the heat exchanger; the DV20 system holds 4.8 l.⁸
To drain the raw water for winter, the DV20 always has two plugs: one under the exhaust manifold and one above the lift pump or behind the starter, depending on the version. Clear the holes with a piece of wire, then run the engine for 30 seconds to blow out the rest; Bukh says this short dry run does not harm the impeller. Never crank the starter for more than 10–15 seconds at a time.⁸
Bukh recommends one BERA 2B zinc on the hull for the DV10 and DV20, bent and clamped to the stern bearing with a stainless hose clip so that it has electrical contact with the propeller; never paint it. If it wears fast, fit two BERA 2B or one BERA 10B; if it does not wear at all, check the electrical connections, including the bonding between gearbox and stern tube.⁸

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.

How to service a Bukh DV20 Video King Country · EN · 19 min
Bukh DV20 zinc anode: where it is and how to replace it Video Flying Doctor Sailing and Exploring · EN · 7 min
Replacing the thermostat on a Bukh DV10/20 Video Left Hand Sailing · EN · 3 min
Protecting a Bukh DV20 against frost (German) Video FrischluftGünni · DE · 14 min

Fitted in

Boats whose builder lists it as standard or optional equipment:

Sadler 32 — Bukh DV20ME 20 hp (Standard from about 1982 (Mike Lucas; 1983 in the SSOA’s data) to 1986, with a 16 × 12 in propeller)

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Sources

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