1998 Volvo Penta AQ125A, AQ125B, AQ145A, AQ145B Inboard Engine Workshop Manual (P/N 7739856-8)

Volvo Penta's November 1998 Engine Unit workshop manual (7739856-8) covers the standard AQ125A, AQ125B, AQ145A, and AQ145B inboard engines used with sterndrives, including standard and US-market electrical arrangements.

Text search and wiring detail: Repair instructions and specification tables have searchable text. Labels within the wiring illustrations are not searchable, and there are no embedded PDF bookmarks. Small labels require zooming; parts of the US wiring diagram remain faint or incomplete at higher magnification.

• Engine repair: Cylinder-head and valve-train disassembly, crankshaft and piston inspection, bearing assessment, flywheel-cover repair, and engine reassembly.

• Timing and valve adjustment: Timing belt replacement, camshaft and intermediate-shaft alignment, valve-clearance inspection, and adjustment shim selection.

• Lubrication: Lubricating oil pump overhaul, gear-clearance and relief-spring checks, oil-filter service, and model-specific oil cooler work.

• Cooling system: Sea water pump inspection, heat exchanger overhaul, circulation pump replacement, thermostat testing, and exhaust pipe service.

• Fuel and ignition: Solex 44 PAI-4 carburetor overhaul and adjustment, distributor contact-breaker replacement, and ignition timing specifications.

• Electrical troubleshooting: Instrument-panel and engine wiring diagrams for standard and USA-execution arrangements, plus a symptom-based fault-finding chart.

Written primarily for Volvo Penta service workshops and qualified personnel, this manual assumes familiarity with marine drive systems and related mechanical and electrical work.

Engine Service Coverage

The repair procedures cover work with the engine removed and secured in a fixture. Flywheel-cover bearings, the primary shaft, and engine-side drive connections are included; internal sterndrive gearcase overhaul is outside this manual's scope.

Technical Data and Model Differences

Separate A- and B-model data sections distinguish piston clearances, crankshaft end float, bearing dimensions, and valve specifications. The B-model cylinder-head procedure uses torque-plus-angle tightening, unlike the A-model procedure. These distinctions help technicians select the correct repair specifications before machining or reassembly.

Component torque tables, fluid-capacity specifications, and valve-spring test data support inspection and assembly work.

Valve service: The B-model data warn against cutting or grinding the valves because this can damage their stellite coating. The AQ125A/AQ145A valve adjusting kit 884516 is listed alongside illustrated shim-adjustment procedures using depressor 9995022 and shim-removal pliers 9995026.

Intermediate shaft: The repair instructions warn that its gear can damage the block's bearing bushings during removal or installation. Alignment coverage connects the crankshaft, intermediate-shaft, and camshaft timing positions.

Solex Carburetors and Ignition

AQ125 uses one carburetor; AQ145 uses two. Exploded views identify the float, needle valve, jets, and accelerator linkage, with separate model settings and a later-engine AQ125 spacer arrangement.

Distributor coverage includes rotor positioning, breaker and condenser replacement, and basic and stroboscopic timing data.

Cooling and Lubrication Service

Heat exchanger and oil cooler exploded views show inserts and sealing arrangements. Oil cooler procedures apply to AQ145; AQ125 uses a different coolant-pipe route.

Sea water pump coverage includes impeller, key, packing, and seal inspection. A damaged circulation pump is replaced as a complete assembly. Oil pump instructions distinguish early and later strainer arrangements and cover oil-pipe seals.

Wiring and Fault Finding

The standard instrument-panel/engine diagram and the USA-execution diagram have separate cable color tables; the US layout also shows flying-bridge instruments.

The fault-finding chart connects starting trouble, stalling, vibration, overheating, and low full-throttle speed with possible causes, helping narrow the systems needing further checks. Maintain adequate ventilation and follow the manual's fuel and electrical safety precautions during service.

English PDF and Included Pages

The manual is supplied as one printable, English-language PDF. The 74-page PDF includes 68 numbered manual pages, two notes pages, front and back covers, one blank page, and a report form; all are already included in the total.