1972 Volvo Penta MD1B, MD2B, MD3B Marine Diesel Engine Workshop Manual (P/N 2668)

This Volvo Penta workshop manual covers repair of the MD1B, MD2B, and MD3B marine diesel engines. Publication No. 2668, December 1972, includes the factory Corrections and Additions sheet.

• Engine repair: Compression testing, cylinder-head and valve work, piston and connecting-rod inspection, crankshaft service, and compression-ratio adjustment.

• Fuel system: Injection-pump removal and installation, control-rod adjustment, Wilbaer-tube timing checks, fuel-system bleeding, and centrifugal-governor service.

• Lubrication: Oil-strainer and filter service, lubricating-oil pump disassembly, reduction-valve inspection, and gear-clearance checks.

• Cooling system: Seawater-pump impeller and seal replacement, thermostat testing, and cooling-circuit illustrations.

• Starting and electrical: Hand-starter servicing and wiring diagrams for dynastarter and separate starter-motor/alternator installations.

• Reverse gears: Type RB and Type MS Mono Shift disassembly, inspection, reassembly, shimming, and shift-mechanism adjustment.

This manual suits mechanics familiar with diesel rebuilding, precision measurements, and the special tools specified for the work.

Cylinder Heads, Bearings, and Compression-Ratio Checks

Cylinder-head repair includes valve-guide replacement, valve-seat grinding, and injector copper-sleeve replacement using puller 884081, fitting drift 884077, and spreader 884085. The cylinder-head tightening diagram distinguishes the fastener groups.

The compression-ratio section explains piston-to-head measurement and cylinder-block shim selection. Together with the corrected gasket data in the addendum, it helps prevent a rebuild calculation from relying on the superseded dimension.

Crankshaft main-bearing replacement, camshaft service, and timing-gear alignment are supported by clearance and wear-limit tables. Valve-adjustment warnings address piston-to-valve contact with the engine running and piston damage from excessive decompressor travel.

Injection-Pump Variants and Calibration Limits

The addendum distinguishes the earlier delivery valve, part No. 243419, from replacement cross-type valve 833743. It supplies model-specific control-rod settings for both arrangements and prohibits mixing valve types in one pump.

Pump mounting measurements and Wilbaer-tube checks support injection-timing adjustment. Additional instructions address pump-element roller sizes when the required timing cannot be obtained.

Specialist work: Internal injection-pump repairs and adjustments are assigned to authorized diesel workshops with suitable test equipment. Exact fuel delivery requires bench testing; control-rod travel measurement provides only a rough adjustment.

Feed-pump service covers diaphragm and valve inspection and pressure testing. Injector checks require a nozzle-testing device; fuel-filter replacement and system bleeding are described separately.

Oil Circulation and Seawater Cooling

The MD2B/RB lubricating-system diagram traces the oil circuit. Oil-strainer access differs between the MD1B/MD2B and the MD3B, while pump inspection includes gear end-clearance and reduction-valve spring checks.

Cooling illustrations include the MD2B/MS system diagram and seawater-pump assembly view. Thermostat-housing service includes a heated-water test. Observe the manual's precautions for water entering the boat during cooling-system work.

Starting Systems and Electrical Connections

Separate wiring diagrams distinguish early MD1B/MD2B dynastarter equipment, later MD2B dynastarter installations with an optional alternator, early MD3B equipment, and later MD2B/MD3B starter-motor installations.

Cable markings and component keys help match the circuit to the installed equipment. Alternator precautions explain the risk of regulator damage if the battery connection is interrupted while the engine runs.

Hand-starter instructions distinguish the MD1B/MD2B assembly from the later MD3B arrangement.

RB and Mono Shift Gear Repair

The RB section covers cone-friction wear assessment and shift-lever setup. MS procedures separate the front, intermediate, and rear housings from the optional reduction gear, with bearing replacement and shaft end-play adjustment.

An RB sectional view and MS exploded assembly illustrate the clutch layouts. Lubrication information distinguishes the RB's shared engine-oil circuit from the MS's separate oil supply.

A Preview of Gasket, Valve, and Fastener Specifications

These examples are a small selection of the manual's engine assembly and adjustment data.

For the covered engines, the addendum corrects compressed cylinder-head gasket thickness to 1.4 mm (0.055 in.), a dimension used in the compression-ratio calculation.

Warm-engine valve clearances are listed as 0.30 mm (0.012 in.) for intake valves and 0.35 mm (0.014 in.) for exhaust valves. The tightening-torque table specifies 700 Nm (506 lb-ft) for the flywheel nut.

PDF Navigation, Diagram Detail, and Page Count

Search, navigation, and legibility: PDF text search and embedded bookmarks are unavailable. Small wiring labels require zooming, and some remain faint. Parts of the wiring diagrams on PDF pp. 29 and 31 are cropped at the page edges; other pages also have cut-off text or illustrations.

The download contains one printable, English-language 45-page PDF: 44 workshop-manual pages, including the cover and introduction, plus a one-page Corrections and Additions sheet. The addendum is already included in the 45-page total.